An Experimental Study on Axisymmetric Turbulence : 5th Report, Suggestion for the Models of Return to Isotropy of the Axisymmetric Turbulence

Abstract

The Reynolds stress model was investigated by analyzing the decay process of a homogeneous turbulence field with extreme axisymmetric anisotropy. The aspect of the change in the model constant of the destruction term in the transport equation of the turbulence energy dissipation rate was assured to vary with the degree of anisotropy defined by the invariant II of anisotropy tendor. The time scale of the decay of turbulence energy was not proportional to the time scale of the energy-containing eddy, L₁/u₁. Rotta's constant for the pressure-strain term was assumed fo change discontinuously as the invariant II decreased in the process of return to isotropy. Better universality was afforded to the model of the pressure-strain term when the anisotropy was assumed to be relaxed with the time scale L₁/u₁.