Impact of the inherent separation of scales in the Navier-Stokes- alphabeta equations.
We study the effect of the length scales alpha and beta in the Navier-Stokes- alphabeta equations on the energy spectrum and the alignment between the vorticity and the eigenvectors of the stretching tensor in three-dimensional homogeneous and isotropic turbulent flows in a periodic cubic domain, including the limiting cases of the Navier-Stokes- alpha and Navier-Stokes equations. A significant increase in the accuracy of the energy spectrum at large wave numbers arises for beta<alpha . The vorticity structures predicted by the Navier-Stokes- alphabeta equations also improve as beta decreases away from alpha . However, optimal choices for alpha and beta depend not only on the problem of interest but also on the grid resolution.
Kim
Tae-Yeon
TY
Department of Mechanical Engineering, McGill University, Montréal, Quebec, Canada H3A 2K6.
Cassiani
Massimo
M
Albertson
John D
JD
Dolbow
John E
JE
Fried
Eliot
E
Gurtin
Morton E
ME