A Turbulence Model for the Three-Dimensional Vortex Blob Method.

Abstract

The purpose of this paper is to propose a turbulence model for the three-dimensional vortex blob method. This model uses a modified version of the core-spreading method introduced by Leonard and Chua (1989) in the spirit of the Smagorinsky type of eddy viscosity. The diffusion of vorticity by the molecular viscosity is represented by the core spreading whose rate is approximated by that of a rectilinear viscous vortex tube. The linear combination of the two viscosities yields a Lagrangian turbulence model, which includes the effects of Reynolds number. We apply each model to an impulsively started round jet forced by two helical disturbances rotating in counter directions and compare the vortical structures of the jet among the models to show that the combined model can be a reasonable turbulence model.