#### DIMOTAKIS, P. E. 1991 "On the convection velocity of
turbulent structures in supersonic shear layers," *AIAA 22*nd
*Fluid Dynamics, Plasma Dynamics and Lasers Conference, *Paper
91-1724.

*Abstract*

An ansatz is proposed, complemented by appropriate selection
rules, to estimate the convection velocity U_{c} of
turbulent vortical structures in low Mach number, supersonic
shear layers. The proposed scheme assumes that, for low
supersonic convective Mach numbers, shocks will form in one of
the two shear layer free streams. The strength of the shocks is
estimated by assuming that the flow configuration, in a frame
moving at the convection velocity U_{c}, is stationary
with respect to perturbations in the mean flow quantities caused
by the turbulent fluctuations. Given the shock strength, the
convection velocity U_{c} and the associated convective
Mach numbers are calculated by matching the estimated total
pressure at stagnation points in the convected frame. Presently
available data indicate a convection velocity U_{c} that
is close to U_{1}, or U_{2}, the high and low
speed stream velocities, respectively, with an empirical stream
selection rule that U_{c} is closer to U_{1},
when the low speed stream is subsonic, and closer to U_{2 }when
both streams are supersonic. With the proviso that the predicted
shock-bearing stream is as suggested by the empirical stream
selection rule, the experimentally observed values for U_{c}
appear to be well accounted for by the proposed scheme. These
results have important implications for supersonic mixing and
hypersonic propulsion applications.