Gas-Liquid Interfaces: Turbulence and Scalar Exchange

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PROPOSAL NO.: CTS-0553333PRINCIPAL INVESTIGATOR: S. BANERJEEINSTITUTION: UNIVERSITY OF CALIFORNIA - SANTA BARBARAGAS-LIQUID INTERFACES: TURBULENCE AND SCALAR EXCHANGE Turbulent transport processes at gas-liquid interfaces remain poorly understood despite being central to many industrial and environmental processes- for example, to reliable estimation of greenhouse gas uptake by the oceans. This poor state of knowledge derives primarily from the difficulty of making measurements and doing numerical simulations of velocity, temperature and concentration fields close to moving, deforming and breaking interfaces. As a result much less is known about turbulence structure and transport processes near mobile interfaces than near solid boundaries, even though many purification, reaction and energy transfer processes are conducted across such interfaces in the chemical and power industries. The objective of this project is to contribute to improving the state of understanding of such problems using a combination of experimental and computational approaches based n recent advances in digital particle imaging velocimetry (DPIV) and direct numerical simulation (DNS) over complex boundaries. In particular, the structure and effects of liquid-side, near-interface turbulence, originating from a variety of sources such as wind shear, wave breaking, thermal convection, wall shear and combinations, will be studied. The proposed experiments and simulations will provide high quality data over a wide range of conditions that will be of lasting value in understanding mechanisms and evaluating modeling approaches. Also the results will be used to assess broad reaching hypotheses regarding turbulent transport processes that if proved valid, would constitute a significant advance in fundamental understanding of the subject. The broad impact of this project arises from its potential to reduce costs for design and scale-up of multiphase-processing equipment, such as condensers, evaporators, gas absorbers, scrubbers and gas-liquid reactors, as well in several environmental applications. These include exchange of carbon between the atmosphere and ocean or river systems, fate and transport of volatile toxics like mercury and PCBs, and the aeration of hypoxic waters. The broad societal impact by better informing policy regarding matters such as greenhouse gas emissions would be very significant. Another impact of the proposed work is its potential to educate researchers in an interdisciplinary area in which both environmental considerations and engineering approaches are important- a background of importance in addressing future societal needs.