## THERMAL SCIENCE

International Scientific Journal

### UNSTEADY MIXED CONVECTION FLOW FROM A SLENDER CYLINDER DUE TO IMPULSIVE CHANGE IN WALL VELOCITY AND TEMPERATURE

**ABSTRACT**

An unsteady mixed convection flow of a viscous incompressible fluid over a non-permeable linear stretching vertical slender cylinder is considered to investigate the combined effects of buoyancy force and thermal diffusion. It is assumed that the slender cylinder is in line with the flow. The unsteadiness in the flow and temperature fields is caused due to the impulsive change in the wall velocity and wall temperature of linearly stretching vertical slender cylinder. The effect of surface curvature is also taken into account, particularly for the applications as wire and fiber drawing where exact predictions are expected. The governing boundary layer equations are transformed into a non-dimensional form by a 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. Numerical computations are performed to understand the physical situations of linear stretching surface for different values of parameters to display the velocity and temperature profiles graphically. 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.

**KEYWORDS**

PAPER SUBMITTED: 2008-05-30

PAPER REVISED: 2011-10-09

PAPER ACCEPTED: 2011-10-10

**THERMAL SCIENCE** YEAR

**2013**, VOLUME

**17**, ISSUE

**Issue 4**, PAGES [1023 - 1034]

- Hitesh Kumar, Heat transfer over a stretching porous sheet subjected to power law heat flux in presence of heat source, Thermal Science (online), (2010), doi:10.2298/TSCI100331074K
- Anilkumar, D., Roy, S., Self-similar solution of the unsteady mixed convection flow in the stagnation point region of a rotating sphere, Heat Mass Transfer, 40 (2004), 6-7, pp. 487 - 493
- Roy, S., Anilkumar, D., Unsteady mixed convection from a rotating cone in a rotating fluid due to the combined effects of thermal and mass diffusion, Int. J. Heat Mass Transfer, 47 (2004), 8-9, pp.1673 - 1684
- Anilkumar, D., Roy, S., Unsteady mixed convection flow on a rotating cone in a rotating Fluid, Applied Math. Comput., 155 (2004), 2, pp. 545 -561
- Chen, T. S., Mucoglu, A., Buoyancy effects on forced convection along a vertical Cylinder, ASME J. Heat Transfer, 97 (1975), 2, pp. 198 -203
- Mucoglu, A., Chen, T. S., Buoyancy effects on forced convection along a vertical cylinder with uniform heat flux, ASME J. Heat Transfer, 98 (1976), 3, pp. 523 -525
- Bui, M. N., Cebci, T., Combined free and forced convection on vertical slender cylinders, ASME J. Heat Transfer, 107 (1985), 2, pp. 476 - 478
- Lee, S. L., Chen, T. S., Armaly, E. F., Mixed convection along a vertical cylinders and needles with uniform surface heat flux, ASME J. Heat Transfer, 109 (1987), 3, pp. 711 -716
- Wang, T. Y., Kleinstruver, C., General analysis of steady mixed convection heat transfer on vertical slender cylinders, ASME J. Heat Transfer, 111(1989), 2, pp. 393 -398
- Takhar, H. S., Chamkha, A. J., Nath, G., Combined heat and mass transfer along a vertical moving cylinder with a free stream, Heat Mass Transfer, 36 (2000), 3, pp. 237-246
- Heckel, J. J., Chen, T. S., Armaly, B. F., Mixed convection along slender vertical cylinders with variable surface temperature, Int. J. Heat Mass Transfer, 32 (1989), 8, pp. 1431 - 1442
- Kumari, M., Nath, G., Mixed convection boundary layer flow over a thin vertical cylinder with localized injection/suction and cooling/heating, Int. J. Heat Mass Transfer, 47 (2004), 5, pp. 969 - 976
- Ishak, A., Nazar, R., Pop, I., The effects of transpiration on the boundary layer flow and heat transfer over a vertical slender cylinder, Int. J. Non-linear Mech, 42 (2007), 8, pp. 1010 - 1017
- Dai, H., Hao, Y., Chen, Z., On constructing the analytical solutions for localizations in a slender cylinder composed of an incompressible hyperelastic material, Int. J. Solids Structures, 45 (2008), 9, pp. 2613 - 2628
- Roy, S., Anilkumar, D., Unsteady mixed convection from a moving vertical slender Cylinder. ASME J. Heat Transfer, 128 (2006), 4, pp. 368 -373
- Singh, P. J., Roy, S. and Pop, I., Unsteady mixed convection from a rotating vertical slender cylinder in an axial flow, Int. J. Heat Mass Transfer, 51 (2008), 5-6, pp.1423 - 1430
- Schlichting, H., Boundary layer theory, Springer, New York, (2000)
- Pop, I., Ingham, D. B., Convective heat transfer: Mathematical and Computational Modelling of Viscous Fluids and Porous Media, Pergman, Oxford, (2001)
- Varga, R. S., Matrix Iterative Analysis, Prentice Hall, Englewood Cliffs, NJ. (2000)