Title: Micro-bubble dispersion in a two-dimensional mixing layer

Authors: Xiaogang Yang, Li Li, Chris Rielly, Xiaobing Huang, Zoubir Zouaoui

Addresses: School of Science and Technology, North East Wales Institute of Higher Education, Wrexham LL11, 2AW, UK. ' The Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire, LE11 3TU, UK. ' Department of Chemical Engineering, Loughborough University, Leicestershire LE11 3TU, UK. ' School of Science and Technology, North East Wales Institute of Higher Education, Wrexham LL11, 2AW, UK. ' School of Science and Technology, North East Wales Institute of Higher Education, Wrexham LL11, 2AW, UK

Abstract: Dispersion of microbubbles (d_b < 100 µm) in a turbulent mixing layer was investigated numerically using a Discrete Vortex Modelling (DVM) while two-way interaction between the dilute dispersed cloud of microbubbles and free-shear layer was taken into consideration. The emphasis of this study is to examine the instantaneous dispersion features of microbubbles entrained by large-scale vortex structures embedded in the free-shear layer, and the effect of interphase momentum coupling on the evolution of the large-scale vortex structures due to the presence of the microbubbles. It was found that the laterally local void fraction profiles achieve similarity conditions downstream of the mixing layer. The simulation revealed that the growth rate of the lateral void fractions is similar to those of the velocity thickness but the lateral void fractions spread greater than the velocity thickness. The correlations between the local void fractions and local vorticity indicated that there is not prominent enhancement of the local void fraction in the centre of the large-scale vortices. In the numerical modelling, two important parameters, drag and lift coefficients in the equation of motion, were also assessed.

Keywords: microbubbles; dispersion; discrete vortex modelling; DVM; two-way coupling; turbulent mixing layers; dilute dispersed cloud; free-shear layer; drag; lift coefficients; equation of motion.

DOI: 10.1504/IJESMS.2008.018848

International Journal of Engineering Systems Modelling and Simulation, 2008 Vol.1 No.1, pp.39 - 47

Published online: 19 Jun 2008 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article