Experiments on particle dispersion in a plane wake
Y. Yang, C.T. Crowe*, J.N. Chung, T.R. Troutt
School of Mechanics and Materials Engineering, Washington State Univerity, Pullman, WA 99164-2920, USA
Received 23 April 1998; received in revised form 10 October 1999
Detailed experimental results are presented concerning the eects of vortex structures on the solid
particle dispersion process in a plane wake. Previous numerical results have indicated that vortex
structures in plane wakes can disperse intermediate Stokes number particles into highly organized
patterns. The cross stream spatial dispersion values associated with these particles were computed to be
several times greater than that associated with ¯uid elements. The major objective of this study was to
obtain direct experimental results concerning the time dependent particle dispersion process in a plane
wake. The experimental approach used in this work primarily involves laser sheet pulsed imaging of
glass bead particles in a wake downstream of a blunt trailing edge. Two sizes of glass beads with
nominal diameters of 10 and 30 mm were used as particles in an air ¯ow. The associated Stokes numbers
of the particles were 0.15 and 1.4. Digital image analysis techniques were employed to identify and
determine particle locations and velocities. The results demonstrate that particle dispersion in plane
wakes can produce highly organized patterns of particle concentrations. The particles at intermediate
Stokes number are focused into sheet-like regions near the boundaries of the large scale vortex
structures. In addition the spatial dispersion of the intermediate Stokes number particles was much
larger than the smaller Stokes number particles. These experimental results strongly support previous
numerical simulation ®ndings. 7 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Particle dispersion; Plane wakes; Vortex structures; Stokes number; Digital image analysis
A substantial amount of experimental and numerical evidence is presently available
concerning the importance of vortex structures in the dispersion of solid particles in two types
International Journal of Multiphase Flow 26 (2000) 1583±1607
0301-9322/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved.
PII: S 0301 - 9 3 2 2 ( 9 9 ) 00 10 5- 6
* Corresponding author. Tel.: +1-509-335-3214; fax: +1-509-335-4662.
E-mail address: firstname.lastname@example.org (C.T. Crowe).