Unsteady mixed convection flow over a rotating vertical slender cylinder under the combined effects of buoyancy force and thermal diffusion with injection/suction has been studied where the slender cylinder is inline with the flow. The effect of surface curvature is also taken into account, especially for the applications such as wire and fiber drawing, where accurate predictions are desired. The governing boundary layer equations along with the boundary conditions are first converted into dimensionless form by a non-similar transformation, and then resulting system of coupled nonlinear partial differential equations is solved by an implicit finite difference scheme in combination with the quasi-linearization technique. The effects of various parameters on velocity and temperature profiles and on skin friction coefficients and heat transfer rate at the wall are reported in the present study. © 2007 Elsevier Ltd. All rights reserved.

Satyajit Roy

Department of Mathematics

Param Jeet Singh

Axial flow

Boundary conditions

Boundary layers

Buoyancy

Finite difference method

Partial differential equations

SKIN FRICTION

Thermal diffusion

SURFACE CURVATURE

UNSTEADY MIXED CONVECTION FLOW

VERTICAL SLENDER CYLINDER

Mixed convection

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IIT Madras

International Journal of Heat and Mass Transfer

This paper presents a numerical investigation on steady triple diffusive mixed convection boundary layer flow past a vertical plate moving parallel to the free stream in the upward direction. The temperature of the plate is assumed to be hotter compared to the surrounded fluid temperature. Sodium chloride and Sucrose are chosen as solutal components which are added in the flow stream from below with various concentration levels. The concentrations of NaCl-Water and Sucrose-Water are considered to be higher near the wall compared to the concentrations of NaCl-Water and Sucrose-Water within the free stream. The coupled nonlinear partial differential equations are transformed using the non-similarity variables and solved numerically by an implicit finite difference scheme with quasi-linearization technique. The effects of Richardson numbers, velocity ratio parameters, ratio of buoyancy parameters and Schmidt numbers of both the solutal components on the fluid flow, thermal and species concentration fields are investigated. Results indicate that the species concentration boundary layer thickness decreases with the increase of Schmidt numbers and that increases with the ratio of buoyancy parameters for both the species components. Overall, the mass transfer rate is found to increase with Schmidt numbers approximately 4.36% and 64.56% for NaCl and Sucrose, respectively. © 2017 Elsevier Ltd

Triple diffusive mixed convection along a vertically moving surface

An unsteady mixed convection flow over a permeable nonlinearly stretching vertical slender cylinder is considered to investigate the combined effects of thermal and mass diffusion in the presence of surface mass transfer and linear chemical reaction, where the slender cylinder is in line with the flow. The unsteadiness in the flow, temperature, and concentration fields is caused by the continuously nonlinearly stretching vertical slender cylinder. The effect of surface curvature is also taken into account, particularly for the applications of wire and fiber drawing where exact predictions are expected. The governing boundary layer equations are transformed into a nondimensional form by a group of nonsimilar transformations. The resulting system of coupled nonlinear partial differential equations is solved by an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical computations are performed to understand the physical situations of linearly and nonlinearly stretching surface for various values of the governing parameters to display the effects of velocity, temperature, and concentration profiles graphically. Our main objective in this work is to focus on opposing flow situations. Numerical results for the local skin-friction coefficient, local Nusselt number, and local Sherwood number are also presented. The present results are compared with previously published work, and these comparisons are found to be in excellent agreement. © 2013 Copyright Taylor and Francis Group, LLC.

Chemical Engineering Communications

Chemical reaction effects on unsteady mixed convection boundary layer flow past a permeable slender vertical cylinder due to a nonlinearly stretching velocity

This paper reports a detailed numerical investigation on mixed convection flow of a polar fluid through a porous medium due to the combined effects of thermal and mass diffusion. The energy equation accounts for heat generation or absorption, while the nth order homogeneous chemical reaction between the fluid and the diffusing species is included in the mass diffusion equation. The governing equations of the linear momentum, angular momentum, energy and concentration are obtained in a non-similar form by introducing a suitable group of transformations. The final set of non-similar coupled non-linear partial differential equations is solved using an implicit finite-difference scheme in combination with quasi-linearization technique. The effects of various parameters on the velocity, angular velocity, temperature and concentration fields are investigated. Numerical results for the skin friction coefficient, wall stress of angular velocity, Nusselt number and Sherwood number are also presented. © 2011 Springer Science+Business Media B.V.

Meccanica

Effects of chemical reaction on mixed convection flow of a polar fluid through a porous medium in the presence of internal heat generation

The objective of the paper is to investigate the numerical study of an unsteady two-dimensional mixed convection flow along a vertical semi-infinite power-law stretching sheet in a parallel free stream with a power-law wall temperature distribution of the form TW(x)=T∞+Ax2m-1. The unsteadiness is caused by the free stream velocity as well as by the stretching sheet velocity. The governing non-linear partial differential equations in the velocity and temperature fields are written in non-dimensional form using suitable transformations. The resulting final set of coupled non-linear partial differential equations is solved using an implicit finite difference scheme in combination with a quasi-linearization technique. The effects of various governing parameters on the velocity and temperature profiles are discussed in the present numerical study. In addition, the numerical results for the local skin friction coefficient and local Nusselt number are also presented. The numerically computed results are compared with previously reported work and are found to be in excellent agreement. © 2010 Elsevier Ltd.

Unsteady mixed convection flow over a vertical stretching sheet in a parallel free stream with variable wall temperature

An unsteady mixed convection flow over a moving vertical plate in a parallel free stream is considered to investigate the combined effects of buoyancy force and thermal diffusion in presence of heat generation or absorption. The unsteadiness is introduced by the time dependent free stream velocity as well as by the moving plate velocity. The governing boundary layer equations are transformed into a non-dimensional form by a special group of non-similar transformations. The resulting system of coupled non-linear partial differential equations is solved by an implicit finite difference scheme in combination with the quasi-linearization technique. Computations are performed and numerical results are displayed graphically to illustrate the influence of the buoyancy (mixed convection) parameter, Prandtl number, the ratio of free stream velocity to the composite reference velocity and heat generation or absorption parameter on the velocity and temperature profiles. The numerical results for the local skin-friction coefficient and local Nusselt number are also presented. Present results are compared with previously published work and are found to be in excellent agreement. It is found that in presence of buoyancy force (λ>0), the velocity profile exhibits velocity overshoot 80% more for lower Prandtl number (Pr=0.7) as compared to the magnitude of the velocity overshoot for higher Prandtl number (Pr=7.0). © 2010 Elsevier Ltd.

Unsteady mixed convection flow from a moving vertical plate in a parallel free stream: Influence of heat generation or absorption

A general analysis has been developed to study flow and heat transfer characteristics of an unsteady laminar mixed convection on a continuously moving vertical slender cylinder with surface mass transfer where the slender cylinder is inline with the flow. The unsteadiness is introduced by the time-dependent velocity of the slender cylinder as well as that of the free stream. The calculations of momentum and heat transfer on slender cylinders considered the transverse curvature effect, especially in applications such as wire and fiber drawing, where accurate predictions are required. The governing boundary layer equations along with the boundary conditions are first cast into a dimensionless form by a nonsimilar transformation, and the resulting system of nonlinear coupled partial differential equations is then solved by an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical results are presented for the skin friction coefficient and Nusselt number. The effects of various parameters on the velocity and temperature profiles are also reported here. Copyright © 2006 by ASME.

Journal of Heat Transfer

Unsteady mixed convection from a moving vertical slender cylinder

The influence of non-uniform slot injection (suction) into steady axi-symmetric laminar incompressible boundary layer flows with temperature dependent viscosity and Prandtl number has been examined from the origin of the streamwise coordinate to the exact point of separation. The difficulties in obtaining the non-similar solutions at the origin of the streamwise coordinate, at the edges of the slot and at the point of separation have been overcome by applying an implicit finite difference scheme with the quasilinearization technique and an appropriate selection of finer step size along the streamwise coordinate. The results indicate that the separation can be delayed by non-uniform slot suction and also by moving the slot downstream but the effect of non-uniform slot injection is just the opposite. Further, the effect of variable fluid properties is to move the point of separation downstream but rotation parameter has the reverse effect. © 2003 Elsevier Science Ltd. All rights reserved.

Journal	Data powered by TypesetInternational Journal of Heat and Mass Transfer
Publisher	Data powered by TypesetElsevier Ltd
ISSN	00179310
Open Access	No