Papers by Keyword: Thermal Radiation

Abstract: This article investigates the boundary layer flow and heat transfer of an electrically conducting Casson fluid over a stretching wedge by considering the effects of suction/injection, velocity and thermal slips and thermal radiation. By applying the appropriate similarity transformations,the governing partial differential equations are transformed to highly non-linear ordinary differential equations. These resulting similarity equations are then solved by a new analytic method namely DTM-BF, based on differential transformation method (DTM) and base function (BF). A comparativestudy of the present numerical results has been made with the already published results available in the literature. The effects of various governing parameters on the flow and heat transfer characteristics have been discussed graphically.

Abstract: The investigation on the interaction between solid and fluid under combined convective flow has been carried out mathematically. The Jeffrey fluid model is taken as the fluid phase and the model is being embedded with the dust particles (solid phase). This two-phase model is constructed by introducing the fluid-particles interaction forces in the momentum equations of the fluid and dust phases, respectively. The natural and forced convections together with the aligned magnetic field are considered on the fluid flow. Also, the Newtonian heating as thermal boundary condition is induced on the vertical stretching sheet. In order to reduce the complexity of the model, the governing equations are transformed from partial differential equation into ordinary differential equation via suitable similarity transformation. The solutions are obtained in terms of velocity and temperature profiles for the fluid and particles phases respectively whereby the Keller-box method is utilized to obtain the desired outcomes. The influences of several significant physical parameters are visualized graphically to clarify the flow and heat transfer characteristic for both phases. The investigation found that the fluid’s velocity is affected by the presence of the dust particles which led to decelerate the fluid transference. The present flow model is able to be compared with the single-phase fluid cases if the fluid-particle interaction parameter is ignored.

Abstract: This study extends previous investigation on ohmic heating of magnetohydrodynamic viscous fluid flow over a continuous moving plate to include radiative heat-loss, viscous dissipation and buoyancy effects. The mathematical formulation representing the modified physical model involves a system of three partial differential equations, which are transformed into a system of two coupled non-linear ordinary differential equations using suitable dimensionless variables. Thereafter, the resulting dimensionless system of equations governing modified model are solved via Homotopy Analysis Method (HAM). The accuracy and convergence of solutions are vali￾dated by comparing the results obtained with those in literature and they are in good agreement. Parametric study is performed to illustrate the effects of emerging parameters on fluid velocity and temperature, skin friction coefficient and Nusselt number. It is found that the impacts of pertinent parameters due to the extensions are significant and these are presented in graphs and tables. The results indicate that the skin friction coefficient and the heat transfer rate increase with the increasing values of thermal radiation and decrease with the increasing value of viscous dissipation parameter.

Abstract: An unsteady magnetohydrodynamic natural convection transfer of mass and heat flow over a vertical porous sheet under the influence of thermal radiation and thermo-diffusion effect. The dimensionless governing equations are solved analytically by employing Laplace transform technique. The impact of various physical parameters on momentum, energy and concentration are discussed and analyzed with the aid of graphs. Furthermore, the numerical values for local Skin friction, Nusselt number and Sherwood number are noted and examined. Increasing the values of thermal diffusion results in increasing of the concentration, but it decreases with Schmidt number. Skin friction reduces for increasing values of thermo-diffusion are discussed with the help of tables.

Abstract: This paper deals with the effect of thermal radiation on the entropy generation of carbon nanotubes water-based nanofluid flow past a moving wedge. Two different types of nanoparticles, namely single wall carbon nanotube (SWCNT) and multi wall carbon nanotube (MWCNT) are considered. Governing equations of the problem are transformed by similarity method into a set of nonlinear ordinary differential equations (ODEs) and solved analytically using optimal homotopy asymptotic method (OHAM). Expression of entropy generation number is obtained in dimensionless form. Further the analytical results of temperature, Nusselt number, skin friction, entropy generation number and Bejan number are discussed and analyzed through graphs. These results show that the entropy generation number has a minimal value for larger radiation parameter and the negative values of velocity ratio parameter λ, while nanoparticles have influence to increase the entropy production.

Abstract: The effects of non-uniform heat source/sink and viscous dissipation on MHD boundary layer flow of Williamson nanofluid through porous medium under convective boundary conditions are studied. Surface transport phenomena such as skin friction, heat flux and mass flux are discussed besides the three boundary layers. The striking results reported as: increase in Williamson parameter exhibiting nanofluidity and external magnetic field lead to thinning of boundary layer, besides usual method of suction and shearing action at the plate, a suggestive way of controlling the boundary layer growth. It is easy to implement to augment the strength of magnetic field by regulating the voltage in the circuit. Also, addition of nano particle to the base fluid serves as an alternative device to control the growth of boundary layer and producing low friction at the wall. The present analysis is an outcome of Runge-Kutta fourth order method with a self corrective procedure i.e. shooting method.

Abstract: An analysis is carried on an unsteady two-dimensional squeezing radiative flow of an incompressible, viscous, electrically conducting fluid in the presence of time-varying transverse magnetic field and chemical reaction. The crux of the analysis centres round, time-varying magnetic field, squeezing of the channel, chemical reaction of diffusing species and radiative heat transfer. These phenomena affect momentum, thermal energy and solutal transport mechanism significantly. The modified governing equations with complex boundary conditions contribute to intricacy of the solution. The Runge-Kutta sixth order integration scheme with shooting technique has been applied to solve the ordinary differential equations under similarity transformations. The analysis reveals that the numerical method applied in the present analysis is as effective and consistent as that of Homotopy Analysis Method (HAM). Further, it is interesting to note that the squeezing of the channel width acts adversely to the resistive force due to the presence of a magnetic field and hence suggests a controlling device to nullify the effect.

Abstract: In this paper, boundary layer flow of non-Newtonian Casson fluids past a semi-infinite porous plate in the presence of thermal radiation, viscous dissipation and heat generation is explored. Fluids of this type act as solid elastic and they are very important in food technology, biological science, etc. The flow took place over a semi-infinite vertical porous plate. The presence of viscous dissipation in the flow equations plays a significant role on flows having high viscosity such as polymers and oils. Thermal radiation and heat generation plays a decisive role in the design of many advanced energy conversion system which operates at higher temperature. Hence, the present study is useful in food processing industries and thermal engineering processes. The flows governing equations are numerically solved with spectral relaxation method (SRM). SRM is an iterative procedure that employs the Gauss-siedel type of relaxation approach to linearize and decoupled the system of coupled differential equations. The influence of controlling parameters on velocity, temperature and concentration profiles are plotted in graphs. Furthermore, numerical computations of the local skin friction, local Nusselt number and local sherwood number are presented in tabular form. Results revealed that the presence of the thermophoresis in the concentration equation has great influence on the velocity and concentration profiles because increasing the thermophoresis parameter intensifies the velocity and concentration profiles.

Abstract: In the present analysis, we extended Blasius and Sakiadis problems in Carreau fluids by considering a uniform free stream parallel to a fixed or moving flat plate, which has more practical significance. The effects of radiation and convective boundary condition are also taken into account. The resulting nonlinear momentum and energy equations are simplified using similarity transformations. Numerical solutions have been obtained for the velocity and temperature profiles by employing shooting method coupled with Runge-Kutta-Fehlberg integration scheme. Graphical results for the velocity and temperature fields are sketched and discussed. It is found that temperature of the Blasius problem is always higher than the Sakiadis problem.

Abstract: This article deals with the analytical study of MHD flow and heat transfer over a permeable stretching sheet via homotopy analysis method (HAM). The effect of thermal radiation is included in the energy equation, while velocity and thermal slips are included in the boundary conditions. The governing boundary layer equations are transformed into a set of ordinary differential equations by means of similarity transformations. The effects of different parameters on the flow field and heat transfer characteristics are examined. The results obtained were shown to compare well with the numerical results and for some special cases with the published data available in the literature, which are in favorable agreement. Keywords: MHD; Slip flow; Stretching sheet; Thermal radiation; Homotopy analysis method