The Lagrangian spectral relaxation model of the scalar dissipation in homogeneous turbulence

The spectral relaxation model of the scalar dissipation rate in homogeneous turbulence

The Lagrangian spectral relaxation model for differential diffusion in homogeneous turbulence

The Lagrangian spectral relaxation ~LSR! model is extended to treat turbulent mixing of two passive scalars (fa and fb) with different molecular diffusivity coefficients ~i.e., differential-diffusion effects!. Because of the multiscale description employed in the LSR model, the scale dependence of differential-diffusion effects is described explicitly, including the generation of scalar decorre...

Improved Lagrangian mixing models for passive scalars in isotropic turbulence

Lagrangian data for velocity, scalars, and energy and scalar dissipation from direct numerical simulations are used to validate Lagrangian mixing models for inert passive scalars in stationary isotropic turbulence. The scalar fluctuations are nearly Gaussian, and, as a result of production by uniform mean gradients, statistically stationary. Comparisons are made for Taylor-scale Reynolds number...

Simulation of Low Reynolds Number Isotropic Turbulence Including the Passive Scalar

Full simulations of homogeneous isotropic turbulence containing a homogeneous passive scalar were made at low Reynolds numbers and various Prandtl numbers. The results show that the spectral behavior of the two fields are quite similar; both fields decay as power-law functions of time. However. the decay exponent is quite dependent on both the Reynolds and Prandtl numbers. The decay exponent of...

Turbulence for (and By) Amateurs

4. Series of lectures on statistical turbulence written for amateurs but not experts. Elementary aspects and problems of turbulence in two and three dimensional Navier-Stokes equation are introduced. A few properties of scalar turbulence and transport phenomena in turbulent flows are described. Kraichnan’s model of passive advection is discussed a bit more precisely. Part 1: Approaching turbule...