Momentum flux fluctuations in wall turbulence formulated along the distance from the wall
arXiv:2306.04942 · doi:10.1063/5.0147875
Abstract
Wall turbulence has a sublayer where the mean wall-normal flux of the streamwise momentum is constant. Via the law of the wall, this mean flux is related to the wall-normal profile of the mean streamwise velocity. However, the momentum flux has large fluctuations, for which the corresponding law is yet unknown. To formulate such a law, we decompose fluctuations of the streamwise and the wall-normal velocities. These are smoothed to single out a component that would dominate the momentum flux fluctuations. It is dependent on the wall-normal distance. We relate this dependence to the wall-normal profile of the streamwise velocity variance. The resultant law is consistent with laboratory and field data across a wide range of that distance and applies readily to wall modeling of a numerical simulation.
10 pages, to appear in Physics of Fluids (see https://pubs.aip.org/aip/pof )