Simulation of Turbulent Heat and Mass Transfer Across Gas-Liquid Interfaces
Abstract
Turbulent heat and mass transfer across gas-liquid interfaces is controlled by layers that are usually substantially less than the order of capillary wave lengths. This allows the evolution of temperature or concentration profiles to be studied by direct numerical simulation. We studied scalar field evolution, when the interface is flat, for relatively high Prandtl numbers (Pr ~ 50). The fluxes vary as Pr^1/3 and Pr^1/2 respectively on the gas and liquid sides, in agreement with experiments and parameterizations based on surface renewal theory. On the gas side, at low Prandtl number, the heat flux is well correlated with the shear stress. When the Prandtl number increases the interface normal velocity fluctuations drive the heat flux. On the liquid side good correlation between sweep events and high heat flux is also observed. The effects of wavy interfaces was also investigated. The vertical motions associated with deforming surfaces become more important when the Prandtl number increases. The heat flux on the gas side is seen to vary as Pr^0.46, when the flow separates and recirculates behind steep waves. This effect is also seen in experiments on heat transfer for flow over sufficiently large roughness elements.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1997
- Bibcode:
- 1997APS..DFD..Bc08D