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.

Satyajit Roy

Department of Mathematics

Boundary conditions

Boundary layers

Cylinders (shapes)

Finite difference method

Heat transfer

linearization

MASS TRANSFER

Nusselt number

Partial differential equations

Unsteady flow

NONSIMILAR SOLUTION

QUASI-LINEARIZATION

SLENDER CYLINDER

UNSTEADY MIXED CONVECTION

Mixed convection

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IIT Madras

Unsteady Mixed Convection From a Moving Vertical Slender Cylinder

Journal of Heat Transfer

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

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.

International Journal of Heat and Mass Transfer

Unsteady mixed convection from a rotating vertical slender cylinder in an axial flow

A semi-similar solution of an unsteady mixed convection flow over a rotating cone in a rotating viscous fluid has been obtained when the free stream angular velocity and the angular velocity of the cone vary arbitrarily with the time. Both the prescribed wall temperature and the prescribed heat flux conditions are considered in the present investigation. The non-linear coupled partial differential equations governing the mixed convection flow have been solved numerically using an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical results are presented for the skin friction coefficients, Nusselt number and Sherwood number. The effects of various parameters on the velocity, temperature and concentration profiles are also reported here. © 2003 Elsevier Ltd. All rights reserved.

Unsteady mixed convection from a rotating cone in a rotating fluid due to the combined effects of thermal and mass diffusion

An analysis is performed to present a new self-similar solution of unsteady mixed convection boundary layer flow in the forward stagnation point region of a rotating sphere where the free stream velocity and the angular velocity of the rotating sphere vary continuously with time. It is shown that a self-similar solution is possible when the free stream velocity varies inversely with time. Both constant wall temperature and constant heat flux conditions have been considered in the present study. The system of ordinary differential equations governing the flow have been solved numerically using an implicit finite difference scheme in combination with a quasilinearization technique. It is observed that the surface shear stresses and the surface heat transfer parameters increase with the acceleration and rotation parameters. For a certain value of the acceleration parameter, the surface shear stress in x-direction vanishes and due to further reduction in the value of the acceleration parameter, reverse flow occurs in the x-component of the velocity profiles. The effect of buoyancy parameter is to increase the surface heat transfer rate for buoyancy assisting flow and to decrease it for buoyancy opposing flow. For a fixed buoyancy force, heating by constant heat flux yields a higher value of surface heat transfer rate than heating by constant wall temperature. © Springer-Verlag 2003.

Heat and Mass Transfer/Waerme- und Stoffuebertragung

Self-similar solution of the unsteady mixed convection flow in the stagnation point region of a rotating sphere

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.

Non-uniform slot injection (suction) into steady laminar water boundary layer flow over a rotating sphere

Heat and Mass Transfer

Combined heat and mass transfer along a vertical moving cylinder with a free stream

International Journal of Heat and Fluid Flow

Nonsimilar solutions for mixed convection on a wedge embedded in a porous medium

Unsteady mixed convection from a moving vertical slender cylinder

Journal	Journal of Heat Transfer
ISSN	00221481
Open Access	No