A SIMPLE THEORY OF CONDITIONAL MEAN VELOCITY IN TURBULENT SCALAR-MIXING LAYER

This paper presents the experimental results on conditional mean transverse velocity across a turbulent scalar mixing layer. The velocity is conditioned on mixture fraction. It is found that the distribution of the conditional mean transverse velocity is closely related to the local mean-mixture fraction in physical space. Near the local mean-mixture fraction a linear relationship exists between the conditional mean transverse velocity and the mixture-fraction fluctuations. Departure from the linear relationship at large mixture-fraction fluctuations is mainly due to the nonlinear distribution of the mean mixture-fraction profile and it is not, as has been suggested by others, due to the limiting velocity of the large eddies in the flow.