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Free convection heat transfer from an isothermal wavy surface in a porous enclosure
Author(s) -
Kumar B. V. Rathish,
Murthy P. V. S. N.,
Singh P.
Publication year - 1998
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/(sici)1097-0363(19980930)28:4<633::aid-fld737>3.0.co;2-s
Subject(s) - mechanics , heat transfer , rayleigh number , enclosure , flow (mathematics) , natural convection , heat flux , isothermal process , materials science , convection , amplitude , isothermal flow , thermodynamics , physics , optics , open channel flow , engineering , telecommunications
The coupled streamfuction–temperature equations governing the Darcian flow and convection process in a fluid‐saturated porous enclosure with an isothermal sinusoidal bottom sun face, has been numerically analyzed using a finite element method (FEM). No restrictions have been imposed on the geometrical non‐linearity arising from the parameters like wave amplitude ( a ), number of waves per unit length ( N ), wave phase ( Φ ), aspect ratio ( A ) and also on the flow driving parameter Rayleigh number ( Ra ). The numerical simulations for varying values of Ra bring about interesting flow features, like the transformation of a unicellular flow to a multicellular flow. Both with increasing amplitude and increasing number of waves per unit length, owing to the shift in the separation and reattachment points, a row–column pattern of multicellular flow transforms to a simple row of multicellular flow. A cycle of n celluar and n +1 cellular flows, with the flow in adjacent cells in the opposite direction, periodically manifest with phase varying between 0 and 360°. The global heat transfer into the system has been found to decrease with increasing amplitude and increasing number of waves per unit length. Only marginal changes in the global heat flux are observed, either with increasing Ra or varying Φ . Effectively, sinusoidal bottom surface undulations of the isothermal wall of a porous enclosure reduces the heat transfer into the system. © 1998 John Wiley & Sons, Ltd.