Spring 2000

ME/IE 8773-8774

ANALYTICAL INVESTIGATION OF TURBULENT GAS-LIQUID FLOWS

by

FARZAD MASHAYEK
Department of Mechanical Engineering
University of Hawaii at Manoa
Honolulu, HI 96822

Wednesday, March 15, 2000
3:35 - 4:25 p.m.
Room 108 ME
Broadcast on UNITE Channel A
Coffee will be available in 152 ME following the seminar

Turbulent gas-liquid flows are of significant engineering importance; but there is much room for further improvements of mathematical models for reliable predictions of such flows. In this talk, we discuss the development of advanced analytical tools for investigation and modeling of turbulent gas-liquid flows with or without evaporation and chemical reaction. Three different, but closely related, areas are considered: (1) single drop dynamics (2) direct numerical simulation (DNS), (3) statistical modeling. Previous treatments of gas-liquid flows are mainly based on inter-phase transfer correlations for "spherical" drops. However, in most of the atomization systems the parent liquid is first disintegrated into long ligaments, which then oscillate towards the attainment of a spherical shape. In (1) we investigate the effects of such oscillations on the inter-phase transfer of mass, heat and momentum for a single drop. The results are then to be incorporated in (2) and (3) for the investigation and modeling of turbulent flows laden with a large number of drops. In DNS, the carrier phase is treated in the Eulerian frame using the Fourier collocation numerical method, and the drops are tracked in the Lagrangian context. Results of the simulations are statistically analyzed to investigate the effects of the turbulence, drops, and combustion time scales on the structure of the reaction zone and on the distribution of the dispersed phase. The statistical modeling is based on the "two-fluid" treatment in which the dispersed phase is also considered in the Eulerian frame. With a liberal use of the Cayley-Hamilton theorem, explicit algebraic models are developed for all of the second-order correlations in the Reynolds averaged transport equations in both phases. The results obtained by models are appraised by detailed comparisons with DNS and available laboratory data. Several of the models as developed are strongly recommended for practical applications.

Prof. Farzad Mashayek received a Ph.D. degree in Mechanical Engineering from the State University of New York at Buffalo in 1994. He served for three years as a Postdoctoral Fellow and a Research Assistant Professor at SUNY/Buffalo prior to joining the University of Hawaii as an Assistant Professor in 1997. Mashayek's research interests are in the areas of turbulence, two-phase flow, combustion, drop dynamics, liquid jet instability, and interface modeling. He received a Young Investigator Award from the ONR and a CAREER award from the NSF in 1999.

Faculty Host: Prof. Paul Strykowski