All Publications |
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Mohammed Jahir Uddin,
R. Nasrin
A numerical appraisal of time-dependent magneto-convective thermal-material transfer over a vertical permeable plate Hindawi, March, 2023 Publication Type: Journal View Summary/Abstract , Publication Link
The objective of this work is to investigate the influences of thermal radiation, heat generation, and buoyancy force on the time-dependent boundary layer (BL) flow across a vertical permeable plate. The fluid is unsteady, incompressible, viscous, and electrically insulating. The heat transfer mechanism happens due to free convection. The nondimensional partial differential equations of continuity, momentum, energy, and concentration are discussed using appropriate transformations. The impressions of thermal radiation and buoyancy forces are exposed in the energy and momentum equation, respectively. For numerical model, a set of nonlinear dimensionless partial differential equations can be solved using an explicit finite difference approach. The stability and convergence analyses are also established to complete the formulation of the model. The thermophysical effects of entering physical parameters on the flow, thermal, and material fields are analyzed. The variations in local and average skin friction, material, and heat transfer rates are also discussed for the physical interest. The analysis of the obtained findings is shown graphically, and relevant parameters pointedly prejudice the flow field. Studio Developer FORTRAN 6.2 and Tecplot 10.0 are applied to simulate the schematic model equations and graphical presentation numerically. The intensifying values of the magnetic field are affected decreasingly in the flow field. The temperature profiles decrease within the BL to increase the value of radiation parameters. The present study is on the consequences for petroleum engineering, agriculture engineering, extraction, purification processes, nuclear power plants, gas turbines, etc. To see the rationality of the present research, we compare these results and the results available in the literature with outstanding compatibility.
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I. Zahan,
R. Nasrin,
S. Hasan
Numerical Simulation of Heat Transfer Performance of Ionanofluid Flow inside Two Connected Oblique Triangular Enclosure SSRN, May, 2023 Publication Type: Conference View Summary/Abstract , Publication Link
Utilizing ionanofluid is one of the best ways to improve the thermal performance of working fluids for storage,
energy conversion, and transportation in contemporary thermal systems. It is a group of nano dispersions where
ionic liquids create the continuous phase. This article's goal is to examine how various nanofluids perform when
the natural convection of long single-walled carbon nanotubes (SWCNTs) nanoparticle occurring in a cavity
which is made up of two connected oblique triangles. The cavity has a thin cold wall (Tc) with angular diameter
√2m. Both halves of the left and bottom walls are heated and kept at constant temperature (Th). The remaining
walls are insulated. The Navier-Stokes equations and energy conservation equation with appropriate boundary
conditions are applied for modeling the considered physics and FEM is used to solve it. The heat-transferring
mediums are assumed as the ionanofluid of SWCNT and 1-butyl-3-methylimidazolium
bis{(trifluoromethyl)sulfonyl}imide ([C4mim][NTf2]) ionic liquid (IL), nanofluid of water-SWCNT and pure
water. The effective parameters in a range of Rayleigh number (103 ≤ 𝑅𝑎 ≤ 106
) and solid concentration (0.1% ≤
𝜙 ≤ 5%) are considered. The findings show that due to higher thermal conductivity and appealing rheological
features of ionanofluid, the heat transfer rate is found significantly higher than nanofluid and pure water. A higher
solid concentration of SWCNTs represents greater values of mean Nusselt number. Additionally, fluid velocity
and heat transfer rate increase at larger values of Ra
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Md. Mehedi Hasan,
M.J. Uddin,
R. Nasrin
Magneto-convective nanofluid flow analysis in a square cavity driven by exothermic chemical reaction Science Direct, November, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
We investigate the unsteady laminar convective magnetohydrodynamic nanofluids flow in a square cavity driven by an exothermic chemical reaction. Because exothermic chemical reactions are intrinsic in nanofluidic flow applications, we consider this exothermic chemical reaction in the analysis, which is governed by Arrhenius kinetics energy. A water-based nanofluid containing iron oxide (Fe3O4) nanoparticles is employed in the simulation. The square cavity is accurately propounded by a combination of suitable heating and flow conditions. The left vertical wall of the enclosure is considered a higher unevenly heated wall, the right vertical wall of the domain is considered a relatively cool constant temperature, and the upper and lower walls are considered insulating walls. Each wall assumes a no-slip condition. The nanofluid governing equations are transformed into the non-dimensional set of equations using similarity analysis and then modified into finite element equations. Galerkin's method in finite element analysis is used to obtain the results of the problem. The results show that the Rayleigh number, the Frank-Kamenetsky number, and the nanosolid volume ratio all have significant effects on the convective flow regime, and the average Nusselt number increases with these parameters. Due to the greater value of the Rayleigh number (Ra = 106), the average Nusselt number increased to 75.92%, and heat generation due to a strongly exothermic reaction (higher Frank-Kamenetskii number) can blow up the bounded solution. The water-Fe3O4 nanofluid achieves a greater rate of heat transfer (maximum 22.65%) than that of the base fluid.
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Md. Mosharrof Hossain,
R. Nasrin ,
Md. Hasanuzzaman
Radiative effect on unsteady magneto-convective heat-mass transport by micropolar binary mixture passing a continuous permeable surface Hindawi, November, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
Radiation is an important branch of thermal engineering which includes geophysical thermal insulation, ground water pollution, food processing, cooling of electronic components, oil recovery processes etc. An analysis of unsteady magneto-convective heat-mass transport by micropolar binary mixture of fluid passing a continuous permeable surface with thermal radiation effect has been introduced in this paper. The governing equations are transformed into coupled ordinary differential equations along with Boussinesq approximation by imposing the similarity analysis. Applying the shooting technique, the obtained non-linear coupled similarity equations are solved numerically with the help of “ODE45 MATLAB” software. The results of the numerical solutions to the problem involving velocity, temperature, concentration and micro-rotation are presented graphically for different dimensionless parameters and numbers encountered. With an increase of suction parameter, the velocity distributions very closed to the inclined permeable wall decrease slightly where . But for the uplifting values of sunction, both micro-rotation profile and species concentration enhance through the boundary layer. The skin-friction coefficient increases about 61%, 13%, 27% for rising values of Prandtl number (0.71-7), radiation effect (0 - 1) and thermal Grashof number (5-10), respectively, but an adverse effect is observed for magnetic field (1 - 4), inclined angle and Schmidt number (0.22 - 0.75). Heat transfer and mass transfer reduce about 82%, 53%, respectively, in increasing of Pr (0.71-1) and 36%, 11%, respectively, in increasing of thermal radiation (0 - 1). The surface couple stress increases about 26%, 49%, 64% and 30% with the increasing values of magnetic field (1-4), inclination angle , suction (0-1) and Schmidt number (0.22-0.75), respectively. Finally, the present study has been compared with the earlier published results. It is observed that the comparison bears a good agreement.
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Shadman Sakib Priam ,
R. Nasrin
Numerical appraisal of time-dependent peristaltic duct flow using Casson fluid Science Direct, November, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
Interruption of continuous process and decreasing flow rate over time are very common challenges in peristaltic flow. This research takes an initiative to restrain the thermal and fluid flow rate over time by unsteady finite element analysis of Casson fluid flow through a two-dimensional peristaltic duct. The time-dependent flow equation exists in conjugate forced convection and the energy equation consists of radiative heat flux and entropy reduction. The top and bottom walls of the peristaltic duct are considered as contact with air. A circular bolus is set up in the middle of the duct. Four types of Casson fluids like slurry, silicone oil, apple juice, and blood are used as working fluids. The finite element method of Galerkin's residual technique is applied to solve the leading second ordered non-linear partial differential equations with proper border conditions. The effects of pertinent parameters on entropy reduction and thermal transport are analyzed. Results are displayed qualitatively in terms of streamlines, vortex field, and heatline contours as well as quantitatively in the form of average temperature, mean thermal, viscous, and total entropy. The obtained numerical results show that thermal performance and entropy reduction are significantly influenced by forced convection, atmospheric characteristics, internal thermal radiation, and Casson fluids. Approximately 6.99% and 72.13% increment of temperature and flow irreversibility are found for shear stress variation of Casson fluid from thickening to thinning. Decreasing thermal performance of 18.71% and increasing energy loss of 38.07% are noticed within the variation of Casson fluids (slurry, silicone oil, apple juice, and blood). About 14.05% enhancement of thermal transport and 64.91% reduction of total entropy are observed due to increasing internal thermal radiation from 0.5 to 2. The numerical results from this research represent a better thermal and fluid flow rate over time compared to the experimental/existing methodology/numerical research. The obtained flow and thermal transport phenomena expose many attention-grabbing performances which deserve additional investigation on Casson fluid characteristics particularly the continuation of flow rate. A fine approach to the biological peristaltic system is offered by the results.
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Tarikul Islam ,
R. Nasrin
Thermal operation by nanofluids with various aspects: A comprehensive numerical appraisal Taylor & Francis , September, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
This research is a good understanding of unsteady convective transport of nanofluids inside a skewed cavity considering MHD, different combinations of base fluids and nanoparticles, shapes, sizes (1–50 nm), volume fractions, and with/without Brownian effects. The right and left sidewalls of the enclosure are heated at low and high temperature, respectively, whereas the bottom and top walls are insulated. The finite element technique with Galerkin’s residual has been implemented for solving non-linear PDEs that govern the flow for the current problem. The numerical simulations have been presented using streamlines, isotherms, and temperature transport rates for different parameters, non-dimensional time, skewed angles, base fluids, nanoparticles, shapes, sizes, and volume fractions. The outcomes show that heat transport rate augments about 12.55% with an additional 2.5% nanoparticles into the base fluid for Cu-H2O nanofluid. An optimal thermal transport rate is observed for kerosene-based nanofluid, blade shape, and 1 nm size of nanoparticles. Magnetite nanoparticles show a greater thermal performance of 4.72% than higher thermal conductivity nanoparticles (copper and cobalt). Thermal transport enhances about 110.78% with Brownian motion for 5% concentrated blade-shaped kerosene-Fe3O4 nanofluid than without Brownian effects. In addition, a new linear regression equation with multiple variables has been derived from the obtained results.
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Amit Kumar Saha ,
Shikha Saha,
Chandra Nath Podder
Effect of awareness, quarantine and vaccination as control strategies on COVID-19 with Co-morbidity and Re-infection Elsevier, 29 September , 2022 Publication Type: Journal View Summary/Abstract , Publication Link
In this paper, a deterministic compartmental model is presented to assess the impact of
vaccination and non-pharmaceutical interventions (social distance, awareness, face mask,
and quarantine) on the transmission dynamics of COVID-19 with co-morbidity and re-
infection. An expression for the basic reproduction number is then derived for this
model. Theoretical analysis shows that the model exhibits backward bifurcation phe-
nomenon when the basic reproduction number is less than unity. But for the case of no re-
infection, the model has a globally asymptotically stable disease-free equilibrium (DFE)
when the basic reproduction number is less than unity. Furthermore, it is shown that in
the case of no re-infection, a unique endemic equilibrium point (EEP) of the model exists
which is globally asymptotically stable whenever the reproduction number is greater than
unity. From the global sensitivity and uncertainty analysis, we have identified mask
coverage, mask efficacy, vaccine coverage, vaccine efficacy, and contact rate as the most
influential parameters influencing the spread of COVID-19. Numerical simulation results
show that the use of effective vaccines with proper implementation of non-pharmaceutical
interventions could lead to the elimination of COVID-19 from the community. Numerical
simulations also suggest that the control strategy that ensures a continuous and effective
mass vaccination program is the most cost-effective control strategy. The study also shows
that in the presence of any co-morbidity and with the occurrence of re-infection, the
disease burden may increase
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Ishrat Zahan,
Md. Kamrujjaman,
Saleh Tanveer
Mathematical Study of a Resource-Based Diffusion Model with Gilpin–Ayala Growth and Harvesting Springer Nature, 15 September, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
This paper focuses on a Gilpin–Ayala growth model with spatial diffusion and Neumann boundary condition to study single species population distribution. In our
heterogeneous model, we assume that the diffusive spread of population is proportional to the gradient of population per unit resource, rather than the population density
itself. We investigate global well-posedness of the mathematical model, determine
conditions on harvesting rate for which non-trivial equilibrium states exist and examine their global stability. We also determine conditions on harvesting that leads to
species extinction through global stability of the trivial solution. Additionally, for
time periodic growth, resource, capacity and harvesting functions, we prove existence
of time-periodic states with the same period. We also present numerical results on the
nature of nonzero equilibrium states and their dependence on resource and capacity
functions as well as on Gilpin–Ayala parameter θ. We conclude enhanced effects of
diffusion for small θ which in particular disallows existence of nontrivial states even
in some cases when intrinsic growth rate exceeds harvesting at some locations in space
for which a logistic model allows for a nonzero equilibrium density.
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Ishrat Zahan,
Md. Kamrujjaman,
Md. Abdul Alim,
Muhammad Mohebujjaman,
Taufiquar Khan
Dynamics of heterogeneous population due to spatially distributed parameters and an ideal free pair frontiers, 09 August , 2022 Publication Type: Journal View Summary/Abstract , Publication Link
Population movements are necessary to survive the individuals in many cases
and depend on available resources, good habitat, global warming, climate
change, supporting the environment, and many other issues. This study
explores the spatiotemporal effect on the dynamics of the reaction-diffusion
model for two interacting populations in a heterogeneous habitat. Both species
are assumed to compete for different fundamental resources, and the diffusion
strategies of both organisms follow the resource-based diffusion toward a
positive distribution function for a large variety of growth functions. Depending
on the values of spatially distributed interspecific competition coefficients, the
study is conducted for two cases: weak competition and strong competition,
which do not perform earlier in the existing literature. The stability of global
attractors is studied for different conditions of resource function and carrying
capacity. We investigated that in the case of weak competition, coexistence
is attainable, while strong competition leads to competitive exclusion. This is
an emphasis on how resource-based diffusion in the niche impacts selection.
When natural resources are in sharing, either competition or predator-prey
interaction leads to competitive exclusion or coexistence of competing
species. However, we concentrate on the situation in which the ideal free pair
is achieved without imposing any other additional conditions on the model’s
parameters. The effectiveness of the model is accomplished by numerical
computation for both one and two space dimension cases, which is very
important for biological consideration
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Ishrat Zahan,
Md. Kamrujjaman,
Md. Abdul Alim
A reaction-advection-diffusion model in spatial ecology: theoretical and computational analysis Khulna University Studies, 26 September, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
In a confined heterogeneous habitat with two species interacting for common resources, the research analyzes a reaction-advection-diffusion type dispersal model with homogeneous Neumann
boundary conditions for generalized growth functions. Both species follow the same symmetric
growths law, but their dispersal strategies and advection rates are different. The following pattern
is used to consider the competition strategy: in a bounded heterogeneous habitat, the first population disperses according to its resource functions, whereas the second population disperses according to its carrying capacity. We investigate the model in two scenarios: when carrying capacity and
resource functions are non-proportional, competitive exclusion occurs, and one species drives the
other to extinction in the long run for various similar and unequal carrying capacities of competing
species. However, coexistence is achievable for different resource distribution consumption if the
resource distribution and the carrying capacity phase of the second species are non-constant and
similar. A series of numerical computations are used to demonstrate the model’s efficacy in oneand two-dimensional instances, which is particularly significant for environmental considera
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I. Zahan,
R. Nasrin,
Shatay Khatun
Thermal performance of ternary-hybrid nanofluids through a convergent-divergent nozzle using distilled water - ethylene glycol mixtures Elsevier, 12 July, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
A computational analysis is conducted based on ternary-nanoparticles performance for base fluid mixture
through a convergent-divergent (CD) nozzle. Since the thermal phenomena through a CD nozzle exposes many
attention-grabbing performances, it deserves additional investigation for laminar flow characteristics. Using
ternary-nanoparticles at different base fluid mixture makes the study more robust and interesting to analyze the
real situation better. In this study, the properties of cobalt (Co), silver (Ag), and zinc (Zn) nanoparticles along
with base fluid mixtures of distilled-water (DW) and ethylene glycol (EG) as (100:0), (60:40), (50:50), and
(0:100), are employed. A wide range of inlet velocity, solid concentrations, nanoparticle size and magnitude of
nanoparticle shape factor is considered in this research. The mixtures of nanoparticles are considered as a ratio of
(0:1/2:1/2), (1/2:0:1/2), (1/2:1/2:0), (1/6:1/6:2/3), (1/6:2/3:1/6), (2/3:1/6:1/6) and (1/3:1/3:1/3). The
mathematical model is formulated using Navier-Stokes equations, energy conservation with proper boundary
conditions, and solved using finite element method. Among the considered base fluid mixtures, the highest heat
transfer rate is obtained for EG-Co-Ag-Zn nanofluid. A relatively higher heat transfer rate is found for all base
fluid mixtures with nanoparticles ratio (1/6:2/3:1/6) compared to other combinations. Furthermore, advanced
rate of thermal transport is found using laminar shape nanoparticles.
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Md. Kamrujjaman,
Ishrat Zahan,
Kamrun Nahar Keya,
Md Nazmul Hassan
Interplay of resource mappings and evolutionary diffusion: Competitive exclusion and coexistence analysis Elsevier, June, 2022 Publication Type: Journal View Summary/Abstract , Publication Link
We study a directed dynamical reaction–diffusion model with no-flux boundary conditions where two populations interact in a spatial heterogeneous closed environment state. Both populations growths are proportional to the same growth law, but the dispersal policies with the migration coefficients differ. The population is diffusing according to their resource functions, and the carrying capacity is bounded in a heterogeneous habitat. This paper’s main results are: if the dispersion functions are non-proportional, then the coexistence is not possible unless the whole environment is homogeneous; and in case of proportionality, the species shows similar behavior. The coexistence is possible if the resource phase and the distribution function of a second organism are identical and non-constant. A few numerical examples verify that the extinction of one species by the other and the coexistence are visible in a non-homogeneous environment.
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R. Nasrin,
S. A. Sweety,
I. Zahan
Turbulent Nanofluid Flow Analysis Passing a Shell and Tube Thermal Exchanger with Kays-Crawford Model American Scientific Publishers, December, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
Temperature dissipation in a proficient mode has turned into a crucial challenge in industrial sectors because of worldwide energy crisis. In heat transfer analysis, shell and tube thermal exchangers is one of the mostly used strategies to control competent heat transfer in industrial progression applications. In this research, a numerical analysis of turbulent flow has been conceded in a shell and tube thermal exchanger using Kays-Crawford model to investigate the thermal performance of pure water and different concentrated water-MWCNT nanofluid. By means of finite element method the Reynold-Averaged Navier-Stokes (RANS) and heat transport equations along with suitable edge conditions have been worked out numerically. The implications of velocity, solid concentration, and temperature of water-MWCNT nanofluid on the fluid flow formation and heat transfer scheme have been inspected thoroughly. The numerical results indicate that the variation of nanoparticles solid volume fraction, inflow fluid velocity and inlet temperature mannerism considerably revolutionize in the flow and thermal completions. It is perceived that using 3% concentrated water-MWCNT nanofluid, higher rate of heat transfer 12.24% is achieved compared that of water and therefore to enhance the efficiency of this heat exchanger. Furthermore, a new correlation has been developed among obtained values of thermal diffusion rate, Reynolds number and volume concentration of nanoparticle and found very good correlation coefficient among the values.
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I. Zahan,
R. Nasrin
An Introduction to Fuzzy Topological Spaces Scientific Research Publishing Inc, 25 May, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
Topology has enormous applications on fuzzy set. An attention can be brought to the mathematicians about these topological applications on fuzzy set by this article. In this research, first we have classified the fuzzy sets and topological spaces, and then we have made relation between elements of them. For expediency, with mathematical view few basic definitions about crisp set and fuzzy set have been recalled. Then we have discussed about topological spaces. Finally, in the last section, the fuzzy topological spaces which is our main object we have developed the relation between fuzzy sets and topological spaces. Moreover, this article has been concluded with the examination of some of its properties and certain relationships among the closure of these spaces.
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Md. Fayz-Al-Asad,
M. N. Alam,
A. M. Rashad,
M. M. A. Sarker
Impact of Undulation on Magneto-Free Convective Heat Transport in an Enclosure Having Vertical Wavy Sides Elsevier, October, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
A computational study has been prepared to explore the impact of undulation on magneto-free convection heat transport in a wavy enclosure bounded by vertical wavy sides and maintaining isothermal boundary condition at the bottom walls while the top wall being adiabatic. Relevant governing equations were discretized by utilizing GWR process of finite element technique. Impact of Hartmann number (0 to 50), the number of waves (between 1 and 3), and Rayleigh number (between 103 and 106) at Pr = 0.71 on the flow phenomena and temperature behavior were studied using streamlines, isotherms, wave effectiveness, mean fluid temperature, and average Nusselt numbers. The numerical outcomes exhibit that the evolution of heat transport in the wavy cavity boosts by ascending the number of undulation (λ = 3) and Rayleigh number. The outcomes are verified associating with the published studies.
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Md. Fayz-Al-Asad,
M. Yavuz,
M. N. Alam,
M. M. A. Sarker,
O. Bazighifan
Influence of Fin Length on Magneto-Combined Convection Heat Transfer Performance in a Lid-Driven Wavy Cavity MDPI, 31 August , 2021 Publication Type: Journal View Summary/Abstract , Publication Link
In the existent study, combined magneto-convection heat exchange in a driven enclosure having vertical fin was analyzed numerically. The finite element system-based GWR procedure was utilized to determine the flow model’s governing equations. A parametric inquiry was executed to review the influence of Richardson and Hartmann numbers on flow shape and heat removal features inside a frame. The problem’s resulting numerical outcomes were demonstrated graphically in terms of isotherms, streamlines, velocity sketches, local Nusselt number, global Nusselt number, and global fluid temperature. It was found that the varying lengths of the fin surface have a substantial impact on flow building and heat line sketch. Further, it was also noticed that a relatively fin length is needed to increase the heat exchange rate on the right cool wall at a high Richardson number. The fin can significantly enhance heat removal performance rate from an enclosure to adjacent fluid.
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Md. Fayz-Al-Asad,
Md. Nur Alam,
M. M. A. Sarker,
Hijaz Ahmed,
M.D. Alsulami,
Khaled A. Gepreel
Impact of a Closed Space Rectangular Heat Source on Natural Convective Flow-through Triangular Cavity Elsevier, April, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
In the existing numerical analysis is developed to impact of a closed space rectangular heat source on natural convective flow-through triangular cavity. The present problem is expressed as non-linear governing equations extended mathematical model is solved by engaging a Galerkin weighted residual process of a finite element scheme. Some investigation is acted for several Rayleigh number (Ra) at Pr = 0.71 on flow pattern and heat variation inside an enclosure. The resulting numerical clarifications of the query are exhibited graphically in phases of streamlines, velocity profiles, isotherms, Rectangular bar effectiveness, mean Nusselt number, and average fluid temperature. The acquired outcomes verified that a rate of heat variation progress with the rise of a Rayleigh number within a triangular cavity. Results are verified relating to a published work.
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Sharaban Thohura,
Md. Mamun Molla,
M. M. A. Sarker ,
Manosh C. Paul
Study of mixed convection flow of power-law fluids in a skewed lid-driven cavity Wiley, May, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
This study conducts a numerical simulation of mixed (combined) convective non-Newtonian fluid flow inside a two-dimensional cavity (skewed) having a moving lid. The upper and bottom extremities of the cavity with different temperatures and two insulated side walls cause natural convection. Moreover, the forced convection is maintained by the motion of the lid with constant velocity. The governing equations are nondimensionalized with appropriate transformations and then transformed into curvilinear coordinates. A finite volume numerical procedure with a collocated grid arrangement is used to solve these equations. Comparisons with previously reported results are carried out, which shows an excellent agreement. Non-Newtonian behaviors such as pseudo-plastic (shear-thinning) and dilatant (shear-thickening) are considered using the power-law model, and thus the power-law index is chosen accordingly. A wide range of the governing dimensionless parameters which affect the mixed convection flow inside the skewed cavity, including Grashof number (), Richardson number (), Reynolds number ( = 100 and 400), and power-law index (). The Prandtl number ( = 10) is fixed and the skew angles (, and ) are considered for acute, right-angle, and obtuse angles. The obtained numerical outcomes of the study are shown graphically and also in tabular form for vertical and horizontal velocities, streamlines, isotherms, temperature distributions, and the rate of heat transfer and insight physics of the flow features, are discussed thereafter. It can be concluded that the rate of heat transfer in the present case is sensitive to the skew-angle as well as power-law index, and the maximum heat transfer occurs in the case of dilatant (shear-thickening) fluid.
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Md. Nahid Hasan
IVESR Rumor Spreading Model in Homogeneous Network with Hesitating and Forgetting Mechanisms ACM, Journal of Applied Mathematics and Computation, 5(2), 105-118. DOI: 10.26855/jamc.2021.06.005, 2021 Publication Type: Journal View Summary/Abstract , Publication Link
In this paper, we study a new IVESR rumor spreading model with hesitating and forgetting mechanisms in homogeneous network. The rumor free and rumor prevailing equilibriums, and the basic reproduction number are calculated from the mean-field equations of the model. The local and global stability of rumor free equilibrium are proved by using Lyapunov function and LaSalle invariance principle, and the existence of rumor prevailing equilibrium is shown. In numerical simulations, it is found that the vaccination, prohibiting people to spread the rumor, can lessen the propagation of rumor in the network. We also show that the fuzziness of the rumor has a great impact on the size of spreader and the forgetting factor has a great effect on the rumor prevailing duration. Furthermore, we analyze the sensitivity of different parameters on and discussed how they affect the spreading and controlling of the rumor.
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Rehena Nasrin,
Saddam Hossain,
Ishrat Zahan,
Khandker Farid Uddin Ahmed ,
Hussain Fayaz
Performance analysis of hybrid/single nanofluids on augmentation of heat transport in lid-driven undulated cavity Wiley, 24 June, 2020 Publication Type: Journal View Summary/Abstract , Publication Link
This numerical study reveals the heat transfer performance of hybrid/single nanofluids inside a lid-driven sinusoidal trapezoidal-shaped enclosure. The right and left inclined surfaces of the trapezium have been considered as insulated, whereas the bottom sinusoidal wavy and the flat top surfaces of the enclosure as hot and cold, respectively. The governing partial differential equations of fluid's velocity and temperature have been resolved by applying the finite element method. The implications of Prandtl number (4.2-6.2), Richardson number (0.1-10.0), undulation number (0-3), nanoparticles volume fraction (0%-3%), and nanofluid/base fluid (water, water–copper (Cu), water–Cu–carbon nanotube, water–Cu–copper oxide (CuO), water–Cu–TiO2, and water–Cu–Al2O3) on the velocity and temperature profiles have been studied. Simulated findings have been represented by means of streamlines, isothermal lines, and average Nusselt number of above-mentioned hybrid nanofluids for varying the governing parameters. The comparison of heat transfer rates using hybrid nanofluids and pure water has been also shown. The heat transfer rate is increased about 15% for varying Richardson number from 0.1 to 10.0. Blending of two nanoparticles suspension in base fluid has a higher heat transfer rate—approximately 5% than a mononanoparticle. Moreover, a higher average Nusselt number is obtained by 14.7% using the wavy surface than the flat surface of the enclosure. Thus, this study showed that applying hybrid nanofluid may be beneficial to obtain expected thermal performance.
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R. Nasrin,
Amzad Hossain,
I. Zahan
Blood Flow Analysis Inside A Stenotic Artery Using Power-Law Fluid Model Crimson Publishers, 03 April, 2020 Publication Type: Journal View Summary/Abstract , Publication Link
This paper is devoted to study numerically a recent development of a non-Newtonian blood flow model
for a stenosed artery in human blood vessel. For numerical investigation the blood flow modeling
method of this research begins with non-Newtonian power-law model. The governing system of equation
based on incompressible Navier-Stokes equations with externally imposed magnetic resonance has
been generalized to take into account the mechanical properties of blood. The intent of this research
is to examine the effects of inlet velocity and imposed magnetic field on the blood flow throughout the
artery. The Galerkin’s weighted residual method of finite element system has been employed to resolve
the governing system of equation with proper boundary conditions. The numerical simulation has been
conducted for various inlet velocities from 0.005 to 0.1m/s and magnetic field strength from 0 to 6
tesla with superior convergence of the iterative structure. Results have been shown in terms of velocity,
surface plot of velocity, pressure and viscosity contours. Cross-sectional plots of velocity and viscosity
magnitudes across the stenotic contraction have also been displayed graphically. Obtained results of the
blood flow simulations indicate that viscosity increases due to increasing values of inlet velocity of blood
and magnetic strength.
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Ishrat Zahan,
R. Nasrin,
M.A. Alim
Mixed convective hybrid nanofluid flow in lid-driven undulated cavity: effect of MHD and Joule heating BanglaJOL, 31 December, 2019 Publication Type: Journal View Summary/Abstract , Publication Link
A numerical analysis has been conducted to show the effects of magnetohydrodynamic (MHD) and Joule heating on heat transfer phenomenon in a lid driven triangular cavity. The heat transfer fluid (HTF) has been considered as water based hybrid nanofluid composed of equal quantities of Cu and TiO2 nanoparticles. The bottom wall of the cavity is undulated in sinusoidal pattern and cooled isothermally. The left vertical wall of the cavity is heated while the inclined side is insulated. The two dimensional governing partial differential equations of heat transfer and fluid flow with appropriate boundary conditions have been solved by using Galerkin's finite element method built in COMSOL Multyphysics. The effects of Hartmann number, Joule heating, number of undulation and Richardson number on the flow structure and heat transfer characteristics have been studied in details. The values of Prandtl number and solid volume fraction of hybrid nanoparticles have been considered as fixed. Also, the code validation has been shown. The numerical results have been presented in terms of streamlines, isotherms and average Nusselt number of the hybrid nanofluid for different values of governing parameters. The comparison of heat transfer rate by using hybrid nanofluid, Cu-water nanofluid, TiO2 -water nanofluid and clear water has been also shown. Increasing wave number from 0 to 3 enhances the heat transfer rate by 16.89%. The enhanced rate of mean Nusselt number for hybrid nanofluid is found as 4.11% compared to base fluid.
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Ishrat Zahan,
R. Nasrin,
M.A. Alim
Hybrid nanofluid flow in combined convective lid-driven sinusoidal triangular enclosure AIP Publishing, 18 July, 2019 Publication Type: Conference View Summary/Abstract , Publication Link
A numerical analysis has been carried out on combined magnetoconvection in a lid driven triangular enclosure with sinusoidal wavy bottom surface filled with hybrid nanofluid composed of equal quantities of Cu and Al2O3 nanoparticles dispersed in water-based fluid. The enclosure left vertical wall is heated while the inclined side of the cavity is cooled isothermally and the bottom wavy wall is insulated. A heat conducting horizontal circular cylinder has been placed at the middle of the enclosure. In this research, the relevant governing equations have been solved by using finite element method of Galerkin weighted residual approach. The implication of Richardson number and solid volume fraction of nanoparticles on the flow structure and heat transfer characteristics has been performed in details while the Reynolds number, Hartmann number and Prandtl number considered as fixed. Results have been presented in terms of streamlines, isotherms and average Nusselt number of the hybrid nanofluid for different values of governing parameters. The numerical results indicate that the Richardson number have significance effect on the flow and heat transfer performance. Moreover, it is noticed that combination of two different nanoparticles suspension has a better performance of heat transfer.
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Sharaban Thohura,
Md. Mamun Molla,
M. M. Alam Sarker
Bingham Fluid Flow Simulation in a Lid-Driven Skewed Cavity using the Finite Volume Method Taylor & Francis , April, 2019 Publication Type: Journal View Summary/Abstract , Publication Link
In this paper, laminar flow of non-Newtonian (Bingham) fluid is studied numerically in a two-dimensional lid-driven skewed cavity that incorporates Papanastasiou exponential regularization approach of Bingham constitutive model [Papanastasiou, Flows of materials with yield, J. Rheol. 31 (1987), pp. 385–404]. Numerical simulation has been done using the finite-volume method with collocated grid arrangement. The governing equations including continuity and momentum are initially non-dimensionalized using appropriate transformation. To simulate irregular shape cavity flow problem, body-fitted non-orthogonal grids are used, and governing equations have been transformed to generalized curvilinear co-ordinates. In this study, two dimensionless parameters namely, Reynolds number and Bingham number are considered. A wide range of skew angles are considered which comprises both acute and obtuse angles. The obtained results are presented in terms of velocity and streamlines with yielded/unyielded region for different values of Bingham number and Reynolds number having different angles of the skewed cavity. The present results may be serve as benchmark results for comparison purpose in the case of non-Newtonian (Bingham) fluid flow.
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Ishrat Zahan,
R. Nasrin,
Md. Abdul Alim
MHD effect on conjugate heat transfer in a nanofluid filled rectangular enclosure MedCrave, January, 2018 Publication Type: Journal View Summary/Abstract , Publication Link
In the present research a numerical solution has been carried out to investigate the problem
of magnetohydrodynamics (MHD) conjugate natural convection flow in a rectangular
enclosure filled with copper water nanofluid. The relevant governing equations have been
solved numerically by using finite element method of Galerkin weighted residual approach.
The investigation uses a two dimensional rectangular enclosure with heat conducting
vertical wall and uniform heat flux. The effect of Hartmann number on the parameter
Rayleigh number, divider position and solid volume fraction of nano particles on the flow
and temperature fields are examined for the range of Hartmann number (Ha) of 0 to 60.
Parametric studies of the fluid flow and heat transfer performance of the enclosure for the
pertinent parameters have also been performed. The numerical results have been provided
in graphical form of streamlines and isotherms for various dimensionless parameters. It is
found that the heat transfer rate increases with an increase of Rayleigh number and divider
position but it decreases with an increase of the Hartmann number. It is also obtained that
an increase of the solid volume fraction enhances the heat transfer performance. Finally, the
implications of the above parameters have been depicted on the average Nusselt number
of the fluid.
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Ishrat Zahan,
M.A. Alim
Effect of Conjugate Heat Transfer on Flow of Nanofluid in a Rectangular Enclosure IIETA, June, 2018 Publication Type: Journal View Summary/Abstract , Publication Link
An elaborate numerical study of developing a model regarding conjugate effect of fluid flow and heat transfer in a heat conducting vertical walled cavity filled with copper-water nanofluid has been presented in this paper. This model is mainly adopted for a cooling of electronic device and to control the fluid flow and heat transfer mechanism in an enclosure. The numerical results have been provided in graphical form showing effect of various relevant non-dimensional parameters. The relevant governing equations have been solved by using finite element method of Galerkin weighted residual approach. The analysis uses a two dimensional rectangular enclosure under conjugate convective conductive heat transfer conditions. The enclosure exposed to a constant and uniform heat flux at the left vertical thick wall generating a natural convection flow. The thicknesses of the remaining parts of the walls are assumed to be zero. The right wall is kept at a low constant temperature, while the horizontal walls are assumed to be adiabatic. A moveable divider is attached at the bottom wall of the cavity. The governing equations are derived for the conceptual model in the Cartesian coordinate system. The study has been carried out for the Rayleigh number Ra =106 and for the solid volume fraction. The investigation is to be arrived out at different non-dimensional governing parameters. The effect of convective heat transfer coefficient, divider position and thickness of solid wall on the hydrodynamic and thermal characteristic of flow has been analyzed. Results are to be presented in terms of streamlines, isotherms and average Nusselt number of the nanofluid for different values of governing parameters.
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Ishrat Zahan,
M.A. Alim
Effects of Rayleigh number and Wall Conductivity on Conjugate Natural Convection of Nanofluid in a Heat Conducting Rectangular Vertical Walled Enclosure AIP Publishing, July, 2018 Publication Type: Conference View Summary/Abstract , Publication Link
The objective of this study is to numerically simulate the effect of conjugate heat transfer in a heat conducting vertical walled cavity filled with Copper-Water nanofluid. The analysis uses a two-dimensional rectangular enclosure under conjugate convective-conductive heat transfer conditions. The enclosure was subject to a constant conduction-convection uniform heat flux at the left wall generating a natural convection flow. The thicknesses of the other boundaries of the wall are assumed to be zero. The right wall is kept at a low constant temperature while the horizontal walls are assumed to be adiabatic. A heat conducting moveable divider is attached on the bottom horizontal wall. The study has been carried out for the Rayleigh number in the range of 104 ≤ Ra ≤ 106 and for the solid volume fraction 0 ≤ ɸ ≤ 0.05. The investigation is to be arrived out at different non-dimensional governing parameters. The effect of Rayleigh number and solid fluid thermal conductivity ratio on the hydrodynamic and thermal characteristic of flow has been analyzed. Results are to be presented in terms of streamlines, isotherms and average Nusselt number of the nanofluid for different values of governing parameters.
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Ishrat Zahan,
M.A. Samad
Radiative Heat and Mass Transfer of an MHD Free Convection Flow Along a Stretching Sheet with Chemical Reaction, Heat Generation and Viscous Dissipation BanglaJOL, January, 2013 Publication Type: Journal View Summary/Abstract , Publication Link |
Nguyen Van Sanh,
S. Asawasamrit,
K. F. U. Ahmed ,
Le Phuong Thao
ON PRIME AND SEMIPRIME GOLDIE MODULES World Scientific, June, 2011 Publication Type: Journal View Summary/Abstract , Publication Link
A right R-module M is called a Goldie module if it has finite Goldie dimension and satisfies the ACC for M-annihilator submodules of M. In this paper, we study the class of prime Goldie modules and the class of semiprime Goldie modules as generalizations of prime right Goldie rings and semiprime right Goldie rings.
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Nguyen Van Sanh ,
Nguyen Anh Vu ,
K. F. U. Ahmed ,
S. Asawasamrit,
Le Phuong Thao
PRIMENESS IN MODULE CATEGORY World Scientific, 2010, 2010 Publication Type: Journal View Summary/Abstract , Publication Link
We introduce the notion of prime submodules of a given right R-module and describe all properties of them as a generalization of prime ideals in associative rings.
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