Mixing of Passive Scalar

The passive scalar evolution is simulated to analyze diffusive properties in the presence of the controller. The passive stands for the one-way coupling assumption. The scalar field has the highest value 5=1 representing the full density at the jet exit and the lowest value 5 = 0 representing a zero density at the ambient field originally. The normalized scalar evolution equation is 

This work was performed under ONR Grant N00014-98-1-0700. 

Grinstein, F. F., E. J. Gutmark, T. P. Parr, D. M. Hanson-Parr, and U. Obeysekare. 1996. Streamwise and spanwise vortex interaction in an axisymmetric jet. A Computation and Experimental Study. Physics Fluids 8(6) 1515-24. 

Nathan. 1999. Effect of small vortex-generators on scalar mixing in the developing region of a turbulent jet. Int. J. Heat Mass Transfer 42 3919-26. 

Gutmark, E. J., and F. F. Grinstein. 1999. Flow control with noncircular jets. An-nual Review Fluid Mechanics 31 239-72. 

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The description of turbulent mixing of passive scalars is based on an extension of the turbulence theory developed for the momentum transfer processes, described in sect 1.2.7. In particular, the energy cascade idea introduced by Richardson [76] and the Kolmogorov hypotheses [47] are adopted. 

In turbulent flows, large scale eddies with coherent structmes are primarily responsible for the mixing of passive scalars. The large scale eddies embody themselves in the form of identifiable and organized distributions of vorticity. In addition, the mixing process involves all mechanisms typically found in vortex dynamics, such as stretching, breakup, concatenation, and self-induction of... 

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