Experimental investigation of transient thermal convection in porous media

Cooper, C.A., Crews, J.B., Schumer, R., Breitmeyer, R.J., Voepel, H. and Decker, D.L. (2014) Experimental investigation of transient thermal convection in porous media. Transport in Porous Media, 104 (2), 335-347. (doi:10.1007/s11242-014-0337-0).

Abstract

A laboratory experiment of transient thermal convection in a 1-m-high cell was conducted to compare the length and time scales of plume development to theory. The temperature field was resolved to less than 1 mm and was measured by dissolving a solution of thermochromic crystals into the water–glycerin working fluid. The time-dependent experiment was run by applying heat at the bottom boundary that eventually was 6oC above the background temperature of the fluid. After development of a thermal boundary layer, the instability became visible at 26 min, with the development of 11, 3–4 cm width plumes growing from the boundary layer. The initially rapid growth rate reached a limiting velocity of approximately 0.5 cm min-1, and then decelerated throughout the experiment. Plumes interacted primarily by merging together; by the end of the experiment only three plumes were present. The Nusselt number at the onset of convection was 10, although it dropped to 4 after 45 min, which would be expected of a barely unstable system.

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Contributors

Author: H. Voepel

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