Library Subscription: Guest
Home Archives Thermal Letter Officers Future meetings Assembly for International Heat Transfer Conferences
International Heat Transfer Conference 13

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

FROM SURFACE RENEWAL TO SURFACE DIVERGENCE: THE EVOLUTION OF MODELS FOR TURBULENT TRANSORT PROCESSES

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

DOI: 10.1615/IHTC13.p30.330
20 pages

Abstract

Exchange of heat and mass across deformable interfaces between turbulent fluids, processes central to many industrial and environmental problems are still poorly understood, despite the considerable effort that has gone into their study. For example, recent studies indicate that liquid-side heat transfer coefficients measured for steam condensation on a subcooled water film, when compared with predictions from computer codes for, say, nuclear loss-of-coolant analyses give differences of one to three orders of magnitude. Turning to environmental applications, prediction of scalar exchange rate at the interface between the atmosphere and terrestrial water bodies also indicates substantial uncertainties, which in turn translate into estimates of oceanic uptake of greenhouse gases such as carbon dioxide that vary by factors of three, depending on the choice of correlation. The low quality of prediction arises from lack of understanding of fluid motion near deforming interfaces, which usually controls scalar exchange. This, in turn, arises from difficulties in measuring and numerically simulating velocity fields in the vicinity of moving surfaces.
The state of the art is reviewed and recent progress in the field summarized. A historical perspective on the development of turbulent transport models is provided, ranging from early surface renewal theories, through their so-called “large-eddy” and “small-eddy” forms, to the current surface divergence models. In particular, the divergence of the tangential velocity fluctuations is shown to provide signatures of subsurface turbulence that are theoretically predicted and experimentally found to correlate with scalar exchange rates. Through use of a blocking theory for homogeneous turbulence modified by interfaces, it is also shown that the surface divergence field, and hence scalar exchange rates, can be related to bulk turbulence parameters such as integral scales. Amongst other practical outcomes of these findings is that remote-sensing of the high wavenumber wave-slope field, which is directly related to surface divergence, may provide reliable regional and global estimates of energy and gas exchange at the air-water interface.

Purchase $25.00 Check subscription Download MARC record Publication Ethics and Malpractice Recommend to my Librarian Bookmark this Page
 

IHTC Digital Library

Measurement of fluid temperature with an arrangement of three thermocouples