Turbulence Dynamics in a Two-Phase Flow

Abstract

Under proper conditions the turbulent flow over a sand bed picks up solid particles. The initial pick up, the suspended transport and the interaction between the two phases depend on the parameters:

$$ Re = \frac{{Uh}}{v}\;Fr = \frac{U}{{\sqrt {gh} }}\;{{\mathop{\rm Re}\nolimits} _s} = \frac{{\left| {{U_f} - {U_s}} \right|d}}{v}\;R = \frac{w}{{k{u^*}}}\;St = \frac{{{t^*}U}}{L}$$

and on the time scales: t* of the particles, t _e of the energetic eddies and t _v of the dissi-pative eddies, that is on:

$$ {t^*} = \frac{{{d^2}{\rho _s}}}{{18v{\rho _f}}}\;{t_e} = \frac{{kv}}{{{u^{*2}}}}{y^ + }\;{t_\eta } = \frac{{{k^{1/4}}V}}{{{u^{*2}}}}{({y^ + })^{1/4}}$$

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