The Effect of an Obstacle Unsteady Wake on Reaction Enhancement Between Two Initially Distant Scalars


The effect of a turbulent wake behind a round obstacle on mixing and reaction between two initially distant scalars has been investigated using a two-channel planar laser-induced fluorescence technique (2C-PLIF). The scalars are stirred and mixed in the mildly turbulent (Re=2000) wake of a round cylinder. The scalars are released continuously upstream of the cylinder, with a separation that initially impedes the reaction. The direct effect of the wake on mixing enhancement is determined by comparing segregation parameter for cases with and without the cylinder obstruction. Results indicate that mixing and reaction rates in the low-Damkohler limit between the two scalars plumes increase with the presence of the cylinder in the domain. The study also shows that the dominant contribution of total reaction derives from the scalar covariance associated with instantaneous flow processes, and depends strongly on streamwise location. In addition, the effect of viscosity and non-Newtonian rheology of the scalars on mixing and reaction has been investigated using a biopolymer called Xanthan Gum. The results have broad implications for biological and ecological mixing processes involving now-Newtonian fluids.

Sep 2, 2014 3:30 PM — 4:30 PM
Bechtel Collaboratory, Discovery Learning Center
Engineering Center, University of Colorado at Boulder, Boulder, CO 80309

University of Colorado Boulder


University of Colorado Boulder