CFD analysis of natural convection between two superposed fluids: role of corrugated bottoms

Abstract

This work is focused on corrugated bottoms role as a means to improving heat performance of cavities filled by two superimposed fluid layers. Physical models examined are square cavities with bottoms subjected to a constant heat flow and sidewalls maintained at cold temperatures. Cavities treated here have been filled with two different fluids. Computational code based on finite volume method has been used to solve two fluid region equations and predict thermal and hydrodynamic fields in two-layer system. Interface between two fluids was assumed to be fixed with null velocities and to be thermally conductive across two fluid regions, where heat flow continuity at this domain boundary was adopted. Mesh has been treated using curvilinear mesh grid in order to take into account corrugated bottoms. Different Rayleigh number values “(103 ≤ Ra ≤ 106)” and different filling rates of two flu ids “(1/3 ≤ h/L ≤ 2/3)” are included in this parametric study. Main objective of our research is focused on corrugated bottoms as a way to improve thermal performance of cavities filled by two fluids, we have opted to examined various forms of corrugation, based on wavelength effects “(0.1 ≤ b ≤ 0.5)” and amplitudes effect “(0 ≤ a ≤ 0.1)” of corrugated backgrounds. Results shows that corrugated bottoms provide an efficient means to improve thermal performances of cavities filled by two fluids. Also, it has been shown that optimal values of wave length and amplitude of corrugated bottoms exist where heat transfer rate reaches its maximum.