Library Subscription: Guest
TSFP DL Home Archives Executive Committee

TURBULENT ENERGY AND DAMPING FUNCTIONS AT GAS-LIQUID INTERFACES AND WAVY WALLS

Valerio De Angelis
Department of Chemical Engineering University of California Santa Barbara Santa Barbara (CA), 93106

Sanjoy Banerjee
Department of Chemical Engineering University of California at Santa Barbara, Santa Barbara, California, 93106

Abstract

Reynolds averaged turbulence models require damping function models, e.g. those of Van Driest and Miner, to correctly describe the behavior of the various turbulence quantities of interest in Computational Fluid Dynamics (CFD). The behavior of such models when boundaries and boundary conditions are complicated is poorly understood. Direct Numerical Simulations (DNS) are presented here for two cases, viz. gas-liquid flow with a flat, horizontal interface (the high surface-tension limit) and gas flow over a wavy boundary. The DNS results are used to validate simple forms of the damping functions. The Miner formulation of the damping function gives satisfactory results on the gas side, whereas the Van Driest formulation is more suitable on the liquid side for the case of turbulent gas and liquid streams coupled across a flat interface. In the case of flow over the wavy wall, Miner's model gives acceptable predictions for u'1u'3 and u'1u'1 but fails to predict u'3u'3. The results are of some practical interest considering that these simple formulations of damping functions are routinely used in CFD codes to solve problems with complex geometries and boundary conditions.