Direct numerical simulation of near-interface turbulence in coupled gas-liquid flow
- Centro per le Tecnologie Energetiche ed Ambientali, Consorzio Pisa Ricerche, Piazza A. DAncona, 1, I-56127, Pisa (Italy)
- Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, California 93106 (United States)
Turbulence structures near the interface between two flowing fluids have been resolved by direct numerical simulation. As a first step the interface has been kept flat, corresponding closely to the recent gas-liquid flow experiments of Rashidi and Banerjee [Phys. Fluids A {bold 2}, 1827 (1990)], with the fluids coupled through continuity of velocity and shear stress boundary conditions. For density ratios between the fluids typical of air and water, the turbulence characteristics on the gas side are quite similar to that in wall regions. The liquid side shows larger velocity fluctuations close to the interface and ejections originate closer to the interface. The mean velocity distribution, turbulence intensities, Reynolds stress and various other statistical measures are significantly altered compared to those in the wall region of channel flows. Quasi-streamwise vortices form in the areas between high and low shear stress on both sides of the interface. At any given instant, about a fifth of these appear to be coupled across the interface. Whether the others are, but the coupling is too weak for the detection technique used, or were coupled previously remains an open question. In any case, sweeps usually occur on the high shear stress side of these vortices and ejections on the low shear stress side. Significant coupling exists across the interface with over 60{percent} of the Reynolds stress in the region close to the interface being associated with coupled events {endash}the main coupling coming through gas ejection-liquid ejection events over low shear stress regions, with a lesser but significant number of gas sweep-liquid sweep events over high shear stress regions. {copyright} {ital 1996 American Institute of Physics.}
- DOE Contract Number:
- FG03-85ER13314
- OSTI ID:
- 284279
- Journal Information:
- Physics of Fluids (1994), Vol. 8, Issue 6; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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