Now showing 1 - 10 of 11
  • Publication
    Mhd mixed convection flow and heat transfer of a dual stratified micropolar fluid over a vertical stretching/ shrinking sheet with suction, chemical reaction and heat source
    ( 2020-01-01)
    Khan A.A.
    ;
    ;
    Sufahani S.F.
    ;
    Ferdows M.
    The purpose of this study was to investigate the magnetohydrodynamic (MHD) mixed convection flow and heat transfer of a dual stratified micropolar fluid over a vertical permeable stretching/ shrinking sheet with chemical reaction and heat source. The governing nonlinear partial differential equations are reduced into a system of nonlinear ordinary differential equations using an appropriate similarity transformation. Then, the obtained ordinary differential equations are solved numerically using the boundary value problem solver (bvp4c) in MATLAB software. The numerical results are tabulated and plotted for the heat transfer characteristics, namely, the skin friction coefficient, the local Nusselt number, the local Sherwood number as well as the velocity, temperature and concentration profiles for some values of the governing parameters. The present numerical results also have been compared with the previous reported results for a particular case and the comparisons are found to be in an excellent agreement. The results indicate that the skin friction coefficient and the local Nusselt number increase with chemical reaction and heat source. The magnitude of the local Sherwood number increases with the increasing of chemical reaction parameter. However, the magnitude of the local Sherwood number decreases with heat source effect.
  • Publication
    Nanofluid stagnation-point flow using Tiwari and Das model over a stretching/shrinking sheet with suction and slip effects
    ( 2020-01-01)
    Yashkun, Ubaidullah
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    ; ;
    Ferdows M.
    In this paper, we considered the stagnation point flow and heat transfer of nanofluid over the stretching/shrinking surface by utilizing of Tiwari and Das nanofluid model. Additionally, the impact of suction and the first order slip likewise have been taken into the account. The system of governing partial differential equations (PDEs) is changed into the system of non-linear ordinary differential equations (ODEs) by means of similarity transformation. The resultant ODEs are solved by using BVP solver (bvp4c) in MATLAB software. The impact of some physical parameters, for example the suction parameter and the slip parameter on the skin friction coefficients and the local Nusselt number as well as the temperature and velocity profiles have been investigated, tabulated and graphically presented. These profiles and variations demonstrate that there exist dual solutions for a specific range of the stretching/shrinking parameter. Both suction and slip effects has enhance the local Nusselt number which represent heat transfer rate at the surface. It is also found that inclusion of both suction and slip effects expands the range of the dual solutions exist. The existence of the dual solutions only occurs in in the shrinking region. The flow separation in the boundary layer delay due to suction and slip effects imposed in the boundary condition.
  • Publication
    Hybrid nanofluid flow through an exponentially stretching/shrinking sheet with mixed convection and Joule heating
    ( 2020-01-01)
    Yashkun U.
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    ;
    Ishak A.
    ;
    Pop I.
    ;
    Sidaoui R.
    Purpose: This study aims to investigate the flow and heat transfer of a hybrid nanofluid through an exponentially stretching/shrinking sheet along with mixed convection and Joule heating. The nanoparticles alumina (Al2O3) and copper (Cu) are suspended into a base fluid (water) to form a new kind of hybrid nanofluid (Al2O3-Cu/water). Also, the effects of constant mixed convection parameter and Joule heating are considered. Design/methodology/approach: The governing partial differential equations are transformed into ordinary differential equations (ODEs) using appropriate similarity transformations. The transformed nonlinear ODEs are solves using the bvp4c solver available in MATLAB software. A comparison of the present results shows a good agreement with the published results. Findings: Dual solutions for hybrid nanofluid flow obtained for a specific range of the stretching/shrinking parameter values. The values of the skin friction coefficient increases but the local Nusselt number decreases for the first solution with the increasing of the magnetic parameter. Enhancing copper volume fraction and Eckert number reduces the surface temperature, which intimates the decrement of heat transfer rate for the first and second solutions for the stretching/shrinking sheet. In detail, the first solution results show that when the Eckert number increases as 0.1, 0.4 and 0.7 at λ = 1.5, the temperature variations reduced to 10.686840, 10.671419 and 10.655996. While in the second solution, keeping the same parameters temperature variation reduced to 9.750777, 9.557349 and 9.364489, respectively. On the other hand, the results indicate that the skin friction coefficient increases with copper volume fraction. This study shows that the thermal boundary layer thickness rises due to the rise in the solid volume fraction. It is also observed that the magnetic parameter, copper volume fraction and Eckert number widen the range of the stretching/shrinking parameter for which the solution exists. Practical implications: In practice, the investigation on the flow and heat transfer of a hybrid nanofluid past an exponentially stretching/shrinking sheet with mixed convection and Joule heating is crucial and useful. The problems related to hybrid nanofluid have numerous real-life and industrial applications, such as microelectronics, manufacturing, naval structures, nuclear system cooling, biomedical and drug reduction. Originality/value: In specific, this study focuses on increasing thermal conductivity using a hybrid nanofluid mathematical model. The novelty of this study is the use of natural mixed convection and Joule heating in a hybrid nanofluid. This paper can obtain dual solutions. The authors declare that this study is new, and there is no previous published work similar to the present study.
      4  3
  • Publication
    Unsteady three-dimensional free convection flow near the stagnation point over a general curved isothermal surface in a nanofluid
    This study deals with an unsteady three-dimensional free convection flow near the stagnation point region over a general curved isothermal surface placed in a nanofluid. Nanofluids are great scientific interest because these new thermal transport phenomena surpass the fundamental limits of conventional macroscopic theories of suspensions. Since the heat and mass transfer are very extensive in the industry, the unsteady three-dimensional body near stagnation point can give a significant impact on the heat transfer process. The main objective of the present study is to investigate the effects of some governing parameters on the skin friction coefficients, local Nusselt and local sheerwood numbers as well as related profiles of unsteady free convection in a nanofluid. The momentum equations in x-and y-directions, energy balance equation, and nanoparticle concentration equation are reduced to a set of four fully-coupled nonlinear differential equations under appropriate similarity transformations. The well-known technique Keller-box method is used numerically for different values of governing parameters entering these equations. Further, the present results have been compared with the previous published results for a particular case and the comparisons are found to be in good agreement. The skin friction, local Nusselt number and Sherwood number is increases with an increase in curvature parameter. Rising values of the Lewis number and Brownian motion parameter has enhanced the flow while rising values of the buoyancy and thermophoresis parameter will decelerate the flow. The temperature profile is increases when Brownian motion, buoyancy and thermophoresis parameter increases and concentration profile increase with an increases in buoyancy and thermophoresis parameter.
      11  26
  • Publication
    Unsteady mhd stagnation point flow of al2o3-cu/h2o hybrid nanofluid past a convectively heated permeable stretching/shrinking sheet with suction/injection
    (Penerbit Akademia Baru, 2022-01-01)
    Khan A.A.
    ;
    ;
    Ying T.Y.
    The numerical investigation of unsteady magnetohydrodynamic (MHD) stagnation point flow of Al2O3-Cu/H2O hybrid nanofluid past a convectively heated permeable stretching/shrinking sheet with suction/injection effect is underlined. The characteristic of MHD and boundary condition with suction/injection has received a lot of consideration due to its across-the-board application in mechanical and chemical engineering. The governing continuity, momentum and energy equations are transformed into a system of nonlinear ordinary differential equations using similarity transformation, which is then solved using the bvp4c routine. Numerical results are obtained for the skin friction coefficient, local Nusselt number as well as the velocity and temperature profiles for certain values of the governing parameters, namely suction/injection parameter, copper nanoparticle volume fraction parameter and MHD parameter. Results showed that both velocity profile and temperature increase as the suction/injection parameter γ increases for the first solution and decreases for the second solution. Similarly, when increase the value of MHD parameter M, the velocity and temperature profiles are decreases for both solutions. The magnitude of the reduced skin friction coefficient and the local Nusselt number are notably increased for the first solution with increasing values of the suction/injection and MHD parameters. Finding also revealed that the skin friction coefficient is intensified in conjunction with the local Nussel number by adding up the copper nanoparticle volume fraction. In general, dual solutions are found to exist to a particular extent of the stretching/shrinking sheet.
      2  24
  • Publication
    Stagnation Point Flow of MHD Nanofluid towards a Permeable Stretching/Shrinking Sheet with a Partial Slip and Heat Source Effects
    ( 2022-06-24)
    Khan A.A.
    ;
    ;
    Ying T.Y.
    The flow of MHD nanofluid towards a permeable stretching/shrinking sheet with chemical reaction, partial slip and heat source effects at the stagnation point has been examined. The state of this partial slip boundary condition and heat source in flow configuration has devoted a considerable attention on account of its widespread application in industrial and chemical engineering. Slip velocity is included to the boundary condition as a part of entrenched stretching/shrinking velocity. The leading partial differential equations are reduced to a set of ordinary differential equation systems with the help of similarity transformations and then it has been clarified utilizing the boundary value problem solver (bvp4c) package in MATLAB. The skin friction coefficient, local Nusselt number, and local Sherwood number, as well as velocity, temperature, and nanoparticle volume fraction profiles for certain values of the leading parameters, namely partial slip parameter and heat source parameter, are calculated numerically in the study. Results indicates that nanoparticle and temperature volume fraction rise as the heat source variable enhances while the velocity remain constant. The size of the skin friction coefficient, Nusselt number, and Sherwood number are all significantly lowered in the first solution when heat source and slip factors rise. For a given range of the stretching/shrinking variable, it is determined that there are two different solutions persist.
      33  1
  • Publication
    Stagnation point flow of williamson nanofluid towards a permeable stretching/shrinking sheet with a partial slip
    ( 2020-01-01)
    Khan A.A.
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    ;
    Ying T.Y.
    The Williamson stagnation nanofluid flow over a stretching/shrinking surface with active and passive control are numerically studied. The main focus of the present study is to investigate the impacts of partial slip and suction at the boundary on the velocity, temperature, and nanoparticle volume fraction profiles and heat transfer characteristics. It is crucial to analyze the fluid flow and heat transfer problems with the inclusion of partial slip and suction effects due to an extensive variety of applications in the industry. The governing partial differential equations are reduced to a set of coupled nonlinear ordinary differential equation systems using nondimensional variables and then it is solved using the boundary value problem solver (bvp4c) in MATLAB. Results show that both velocity and nanoparticle volume fraction increase as the suction parameter increases while the temperature acts in the opposite manner. The magnitude of the reduced skin friction coefficient, the reduced Nusselt number and the reduced Sherwood number are notably increased for the first solution with the increasing suction parameter. It is seen that the nanofluid velocity increases as the partial slip parameter increases whereas the temperature and nanoparticle volume fraction of the nanofluid are decreased. As partial slip parameter enhanced, the reduced skin friction coefficient has decreased while the magnitude of both the local Nusselt number and the local Sherwood number are increasing. Dual solutions exist up to a certain range of the stretching/shrinking parameter in the shrinking flow region. The critical values of stretching/shrinking parameter increases with the increasing in suction and partial slip effect strength suggest that both parameter widens the range of dual solutions exist. Physically, the increment of the suction and slip effects has delayed the boundary layer separation. The first solution is found to be stable and physically applicable but the second solution is not based on the literature for the similar problem presented by researchers.
      3  17
  • Publication
    Dissipative-radiative micropolar fluid transport in a non-darcy porous medium with cross-diffusion effects
    ( 2020-01-01)
    Ferdows M.
    ;
    Shamshuddin M.D.
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    In this work, the micropolar fluid flow and heat and mass transfer past a horizontal stretching sheet through a porous medium are studied including the Soret-Dufour effect in the presence of viscous dissipation. A uniform magnetic field is applied transversely to the direction of the flow. The governing differential equations of the problem are transformed into a system of non-dimensional differential equations which are solved numerically by Nachtsheim-Swigert iteration technique along with the sixth order Runge-Kutta integration scheme. The velocity, microrotation, temperature and concentration profiles are presented for different parameters and interpreted at length. Results show that with an increase in vortex viscosity ratio parameter, suction parameter and radiation parameter, velocity is decreased whereas it increases with the increase of magnetic parameter, Darcy number and Eckert number. Angular velocity significantly elevated by increasing the suction parameter, surface nonlinearity parameter and magnetic parameter. Temperature gradient escalate with the increase of magnetic parameter and Dufour number, while a reverse trend is observed in case of increase of Darcy number, Eckert number and Soret number. Concentration gradient putrefies with Schmidt number and Dufour number. However, concentration grows with Soret number. The present problem finds significant applications in hydromagnetic control of conducting polymeric sheets and magnetic materials processing.
      28  1
  • Publication
    Flow and heat transfer of a nanofluid through a porous medium due to stretching/shrinking sheet with suction, magnetic field and thermal radiation
    ( 2023-09-01)
    Yashkun U.
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    Sufahani S.F.
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    Eid M.R.
    ;
    Ferdows M.
    This study investigates the suction and magnetic field effects on the two-dimensional nanofluid flow through a stretching/shrinking sheet at the stagnation point in the porous medium with thermal radiation. The governing partial differential equations (PDEs) are converted into ordinary differential equations (ODEs) using the similarity transformation. The resulting ODEs are then solved numerically by using the bvp4c solver in MATLAB software. It was found that dual solutions exist for the shrinking parameter values up to a certain range. The numerical results obtained are compared, and the comparison showed a good agreement with the existing results in the literature. The governing parameters’ effect on the velocity, temperature and nanoparticle fraction fields as well as the skin friction coefficient, the local Nusselt number and the Sherwood number are represented graphically and analyzed. The variation of the velocity, temperature and concentration increase with the increase in the suction and magnetic field parameters. It seems that the thermal radiation effect has increased the local Sherwood number while the local Nusselt number is reduced with it.
      2  14
  • Publication
    Stability analysis on stagnation-point flow and heat transfer towards a permeable stretching/shrinking sheet with heat source in a casson fluid
    This paper deals with a stagnation-point boundary layer flow and heat transfer of a Casson fluid towards a stretching/shrinking sheet. The main objective of the present study is to analyse the effects of the injection parameter and heat source on the velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number. It is vital to study the heat transfer and fluid flow problems in the presence of injection and heat source effects due to a wide variety of applications in engineering and industry. The governing nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations by using similarity transformation, before being solved numerically using the boundary value problem solver bvp4c routine in MATLAB. Dual solutions are found to exist for the shrinking sheet case, whereas the solution is unique for the stretching case. The stability analysis has been performed to determine the stable solution. It is shown that the first solutions are stable and physically reliable while the second solutions are not. Further, the present results have been compared with the previous published results for a particular case and the comparisons are found to be in good agreement. The local Nusselt number is decreases with an increase in heat source parameter. Rising values of the injection parameter has decreases both the skin friction coefficient and the local Nusselt number.
      5  16