Computer simulation of double diffusive convection and rollover of binary mixtures in cylindrical vessels

Conference · Wed Jul 01 04:00:00 EDT 1998

OSTI ID:20000356

Rujano, J R; Rahman, M M; Crane, R A

The study of the behavior of fluid flow and convective heat and mass transfer in a stratified fluid system is of interest in various areas of science and engineering. Double diffusive convection processes are observed, for instance in LNG storage tanks, fire phenomena with petroleum mixtures, thermal energy storage in solar ponds, and ocean and atmospheric circulation. In this paper, the spontaneous destabilization of a stably stratified fluid in a vessel due to the reversal of the density gradient, caused by heat and mass transfer is investigated. This study models the process by numerically solving the transient momentum, energy, and mass transfer equations for a binary solution in a cylindrical enclosure. Initially the fluid is stably stratified with the upper layer having a higher concentration of the lighter component. Heating through the walls is then applied, resulting in buoyancy-driven convection accompanied by heat and mass transfer, and finally in rollover. The numerical model is validated by comparison with a previously reported numerical simulation of such a phenomenon verified by experimental findings. The basic phenomena observed in this computational investigation was found to be similar to that described in the formerly reported numerical study. However, the present simulation reveals a faster evolution of the process and a more intensive buoyancy induced convection. This difference is caused by an incorrect definition of vorticity, which leads to an inappropriate form of the momentum equation, used in the computations chosen for comparison. Furthermore, the model is used to compare numerical results obtained using both finite element and finite volume based CFD software. Results indicate that the solution obtained using the finite volume based code are more realistic and consistent with previously reported results.

• Research Organization: University of South Florida, Tampa, FL (US)
• OSTI ID: 20000356
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BINARY MIXTURES
CONVECTION
CYLINDERS
MATHEMATICAL MODELS
NUMERICAL ANALYSIS
STRATIFICATION