Abstract
Mechanisms governing heat and mass transfer at air-water interfaces may be studied experimentally and by mean of Direct Numerical Simulations (DNS). Flow visualizations play a central role in unraveling the mechanisms that govern these transfer rates. In particular visualizations show that the flow is organized in large structures. These are sweeps, high-speed (relative to the interface velocity) fluid traveling toward the interface, and ejections, low speed fluid moving away from the interface region. It is the frequency with which these large flow structures refresh the interface that controls mass transfer.
On the liquid side, flow fluctuations in the near-interface region are relatively unimpeded, so fluid poor in solute can be transported by sweeps to the interface, and then pick up solute through diffusion before being carried away again. On the gas side, flow fluctuations in the near-interface region are strongly impeded, so mass transfer is controlled by sweeps and ejections, i.e., any events with significant interface-normal velocity.
The frequency, with which these large flow structures are generated, can be computed from the DNS. Simple parameterizations, based on the mechanisms discussed above, can be developed and appear to predict mass transfer velocities in excellent agreement with experimental and numerical results. The parameterizations capture the effect of capillary waves.
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References
S. Banerjee, “A note on Turbulent Mass Transfer at High Schmidt Numbers,” Chem. Eng. Science, (1971), 26, 989–990.
S. Banerjee, “Turbulence structure and transport mechanisms at interfaces,” Proceedings of the Ninth International Heat Transfer Conference, Jerusalem, Israel, 1990, 395–417.
P. S. Bernard, J. M. Thomas and R. A. Handler, “Vortex dynamics and the production of Reynolds stress,” J. Fluid Mech., 253, (1993), 385.
V. De Angelis, “Numerical Investigation and Modeling of Mass Transfer Processes at Sheared Gas-Liquid Interfaces,” Ph.D. Dissertation, University of California at Santa Barbara, 1998.
G. S. Hirschberg, “Direkte Simulation der turbulenten Taylor-Couette Stromung und der ebenen Kanalstromung,”,Ph.D. Dissertation, ETHZurich, (1992).
J. Klinke and B. Jahne, “Measurements of Short Ocean Waves during the MBL ARI WEST Coast Experiments,” Air-water Gas Transfer — Third Int. Symposium on Air-Water Gas Transfer, (1995), 165–173.
S. Kumar, R. Gupta and S. Banerjee, “An experimental investigation of the characteristics of free-surface turbulence in channel flow,” Physics of Fluids 10, (1998), 437.
L. G. Leal, “Laminar flow and convective transport processes: Scaling principles and asymptotic analysis,” Butterworth-Heinemann, Stoneham (MA), USA, (1992).
P. Lombardi, V. De Angelis and S. Banerjee, “Direct numerical simulation of near-interface turbulence in coupled gas-liquid flow,” Physics of Fluid, 8, (1996), 1643–1665.
M. J. McCready and T. Hanratty, “Effect of air shear on gas absorption by a liquid film,” AIChE Journal, 31(12), (1985), 2066–74.
F. J. Ocampo-Torres, F. J. Donelan, J.M. Woollen and J. R. Koh, “Laboratory measurements of Mass Transfer of Carbon Dioxide and water Vapor for Smooth and Rough flow conditions,” Tellus Series B, 46, (1994), 16–28.
M. Rashidi and S. Banerjee, “The effect of boundary Conditions and Shear rates on Streaks formation and breakdown in Turbulent channel flow,” Physics of Fluid, (1990), A2, 1827–38.
R. H. Wanninkhof and L. F. Bliven, “Relationship between gas exchange, wind speed, and radar back-scatter in a large wind wave tank,” J. of Geophysical Research, 96(C2), (1991), 2785–2796
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Valerio De Angelis: He completed the Ph.D. program of the department of Chemical Engineering at UCSB in ′98. He developed methods for DNS of turbulent flow and mass transfer at high Schmidt numbers. He is currently working in a software engineering company (MetaHeuristics-Santa Barbara (CA) 93105, US) where he is participating in the implementation of level-set methods (for multiphase flows) in commercial codes. His other scientific interests include artificial intelligence and gas-lattice methods. He can be contacted at valerio@anemone.ucsb.edu.
Sanjoy Banerjee: He has been active in investigating multiphase phenomena since the early ′70s including the use of optical methods and DNS. His other academic interests include dynamic large-eddy simulation models, DNS methods based on wavelets, level-set methods for multiphase flows, flow visualization of wave micro breaking and development of new DPIV techniques. He can be contacted at banerjee@anemone.ucsb.edu.
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De Angelis, V., Banerjee, S. The role of visualization in clarifying interfacial heat and mass transfer mechanisms. J Vis 2, 159–167 (1999). https://doi.org/10.1007/BF03181519
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DOI: https://doi.org/10.1007/BF03181519