High Schmidt-number turbulent advection and giant concentration fluctuations

Reynolds number dependence of scalar fluctuations in a high Schmidt number turbulent jet

The scalar rms fluctuations in a turbulent jet were investigated experimentally, using highresolution, laser-induced fluorescence techniques. The experiments were conducted in a high Schmidt nuinber fluid (water), on the jet centerline, over a jet Reynolds number range of 3000<Re<24 000. It was found that the normalized scalar rms fluctuations c’/ C decrease with increasing flow Reynolds number...

Influence of Schmidt number on the fluctuations of turbulent mass transfer to a wall

Measurements are presented on the influence of Schmidt number on the frequency of the mass transfer fluctuations at a solid boundary. The shape of the spectral function is similar at all Schmidt numbers. A relation between the mass transfer fluctuations and the fluctuating velocity field can be obtained only at high frequencies. A comparison of the scale and the frequency of the mass transfer f...

A Variable Turbulent Schmidt Number Formulation for Scramjet Application

In high speed engines, thorough turbulent mixing of fuel and air is required to obtain high performance and high efficiency. Thus, the ability to predict turbulent mixing is crucial in obtaining accurate numerical simulation of an engine and its performance. Current state of the art in CFD simulation is to assume both turbulent Prandtl number and Schmidt numbers to be constants. However, since ...

On filtering in the viscous-convective subrange for turbulent mixing of high Schmidt number passive scalars

Turbulent Prandtl number effect on passive scalar advection

A generalization of Kraichnan’s model of passive scalar advection is considered. Physically motivated regularizations of the model are considered which take into account both the effects of viscosity and molecular diffusion. The balance between these two effects on the inertial range behavior for the scalar is shown to be parameterized by a new turbulent Prandtl number. Three different regimes ...