EFFECT OF REYNOLDS-NUMBER ON ISOTROPIC TURBULENT DISPERSION

The influence of the spatio-temporal structure of isotropic turbulence on the dispersion fluid and particles with inertia is investigated. T he spatial structure is represented by an extended von Karman energy s pectrum model which includes an inertial sub-range and allows evaluati on of the effect of the turbulence Reynolds number, Re(l)ambda. Disper sion of fluid is analyzed using four different models for the Eulerian temporal auto-correlation function D(tau). The fluid diffusivity, nor malized by the integral length scale L(11) and the root-mean-square tu rbulent velocity u(0), depends on Re-lambda. The parameter c(E) = T(0) u(0)/L(11), in which T-0 is the Eulerian integral time scale, has comm only been assumed to be constant. It is shown that c(E) strongly affec ts the value of the fluid diffusivity. The dispersion of a particle wi th finite inertia and finite settling velocity is analyzed for a large range of particle inertia and settling velocity. Particle turbulence intensity and diffusivity are influenced strongly by turbulence struct ure.