The myth of URANS

Since the 1990s, RANS practitioners have observed spontaneous unsteadiness in simulations. Some suggested deliberately using this as a method of resolving large turbulent structures. However, to date, no one has produced theoretical justification for unsteady (URANS) approach. Here, we extend dynamical system fixed point analysis create model URANS dynamics. The results are compared simulations homogeneous isotropic decaying turbulence. shows that can predict incorrect decay rates and solution tends towards steady over time. Similar forced turbulence modelled energy about 30% total energy, regardless parameters. same be used show how hybrid type models begin address these issues.