Comment on “Diffusion by a random velocity field” [Phys. Fluids 13, 22 (1970)]

This comment aims at addressing amass conservation issue in a paper published in the physics of fluids. The paper [R. H. Kraichnan, “Diffusion by a random velocity field,” Phys. Fluids13(1), 22 (1970)] introduces a novel method to generate syntheticisotropic turbulence for computational purposes. The method has been used in the literature to generate inletboundary conditions and tomodelaeroacousticnoise as well as for validation and verification purposes. However, the technique uses a continuous formulation to derive themass conservation constraint. In this comment, we argue that the continuous constraint is invalid on a discrete grid and provide an alternative derivation using the discrete divergence. In addition, we present an analysis to quantify the impact of a pressure projection on the kineticenergy of a non-solenoidal velocity field.

Source: Physics of Fluids - November 30, 2016 Category: Physics Authors: Tony Saad and James C. Sutherland Source Type: research