Abstract
This paper presents an analytical and numerical study of transient free convection from a horizontal surface that is embedded in a fluid-saturated porous medium. It is assumed that for time \(\bar \tau < 0\) steady state velocity and temperature fields are obtained in the boundary-layer which occurs due to a uniform flux dissipation rate q 1′′ on the surface. Then, at \(\bar \tau = 0\) the heat flux on the surface is suddenly changed to q 2′′ and maintained at this value for \(\bar \tau > 0\). Firstly, solutions which are valid for small and large \(\bar \tau \) are obtained. The full boundary-layer equations are then integrated step-by-step for the transient regime from the initial unsteady state (\(\bar \tau = 0\)) until such times at which this forward marching approach is no longer well posed. Beyond this time no valid solutions could be obtained which matched the final solution from the forward integration to the steady state profiles at large times \(\bar \tau \to \infty \).
Similar content being viewed by others
References
Chang, I. D. and Cheng, P.: 1983, Matched asymptotic expansions for free convection about an impermeable horizontal surface in a porous medium, Int. J. Heat Mass Transfer 26, 163-174.
Chaudhary, M. A., Merkin, J. H. and Pop, I.: 1996, Natural convection from a horizontal permeable surface in a porous medium - numerical and asymptotic solutions, Transport in Porous Media 22, 327-344.
Cheng, P. and Chang, I. D.: 1976, Buoyancy induced flows in a saturated porous medium adjacent to impermeable horizontal surfaces, Int. J. Heat Mass Transfer 19, 1267-1272.
Dennis, S. C. R.: 1972, The motion of a viscous fluid past an impulsively started semi-infinite flat plate, J. Inst. Math. Appl. 10, 105-117.
Harris, S. D., Ingham, D. B. and Pop, I.: 1996, Transient free convection on a vertical plate subjected to a change in surface heat flux in porous media, Fluid Dynam. Res. 18, 313-324.
Harris, S. D., Ingham, D. B. and Pop, I.: 1997a, Free convection from a vertical plate in a porous medium subjected to a sudden change in surface heat flux, Transport in Porous Media 26, 207-226.
Harris, S. D., Ingham, D. B. and Pop, I.: 1997b, Free convection from a vertical plate in a porous media subjected to a sudden change in surface temperature, Int. Comm. Heat Mass Transfer 24, 543-552.
Harris, S. D., Elliott, L., Ingham, D. B. and Pop, I.: 1998, Transient free convection flow past a vertical flat plate subjected to a sudden change in surface temperature, Int. J. Heat Mass Transfer 41, 357-372.
Higuera, F. J.: 1997, Conjugate natural convection heat transfer between two porous media separated by a horizontal wall, Int. J. Heat Mass Transfer 40, 3157-3161.
Higuera, F. J. and Weidman, P. D.: 1995, Natural convection beneath a downward facing heated plate in a porous medium, Euro. J. Mech. B/Fluids 14, 29-40.
Ingham, D. B. and Pop, I. (eds): 1998, Transport Phenomena in Porous Media, Elsevier, Oxford.
Ingham, D. B., Merkin, J. H. and Pop, I.: 1985, Flow past a suddenly cooled horizontal flat surface in a saturated porous medium, Acta Mechanica 56, 205-217.
Johnson, C. H. and Cheng, P.: 1978, Possible similarity solutions for free convection boundary layers adjacent to flat plates in porous media, Int. J. Heat Mass Transfer 21, 709-718.
Lesnic, D., Ingham, D. B. and Pop, I.: 1995, Conjugate free convection from a horizontal surface in a porous medium, J. Appl. Math. Mech. (ZAMM) 75, 715-722.
Merkin, J. H.: 1972, Free convection with blowing and suction, Int. J. Heat Mass Transfer 15, 989-999.
Merkin, J. H. and Zhang, G.: 1990, On the similarity solutions for free convection in a saturated porous medium adjacent to impermeable horizontal surfaces, Wärme-und Stoffübertr. 25, 179-184.
Nakayama, A.: 1995, PC-Aided Numerical Heat Transfer and Convective Flow, CRC Press, Tokyo.
Nield, D. A. and Bejan, A.: 1999, Convection in Porous Media, 2nd edn, Springer-Verlag, New York.
Pop, I. and Cheng, P.: 1983, The growth of a thermal layer in a porous medium adjacent to a suddenly heated semi-infinite horizontal surface, Int. J. Heat Mass Transfer 26, 1574-1576.
Rees, D. A. S.: 1996, The effect of inertia on free convection from a horizontal surface embedded in a porous medium, Int. J. Heat Mass Transfer 39, 3425-3430.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Harris, S.D., Ingham, D.B. & Pop, I. Transient Free Convection from a Horizontal Surface in a Porous Medium Subjected to a Sudden Change in Surface Heat Flux. Transport in Porous Media 39, 97–117 (2000). https://doi.org/10.1023/A:1006697816838
Issue Date:
DOI: https://doi.org/10.1023/A:1006697816838