English

Predictions of canonical wall bounded turbulent flows via a modified $k-\omega$ equation

Fluid Dynamics 2016-12-21 v1

Abstract

A major challenge in computation of engineering flows is to derive and improve turbulence models built on turbulence physics. Here, we present a physics-based modified kωk-\omega equation for canonical wall bounded turbulent flows (boundary layer, channel and pipe), predicting both mean velocity profile (MVP) and streamwise mean kinetic energy profile (SMKP) with high accuracy over a wide range of Reynolds number (ReRe). The result builds on a multi-layer quantification of wall flows, which allows a significant modification of the kωk-\omega equation. Three innovations are introduced: First, an adjustment of the Karman constant to 0.45 is set for the overlap region with a logarithmic MVP. Second, a wake parameter models the turbulent transport near the centerline. Third, an anomalous dissipation factor represents the effect of a meso layer in the overlap region. Then, a highly accurate (above 99\%) prediction of MVPs is obtained in Princeton pipes, improving the original model prediction by up to 10\%. Moreover, the entire SMKP, including the newly observed outer peak, is predicted. With a slight change of the wake parameter, the model also yields accurate predictions for channels and boundary layers.

Keywords

Cite

@article{arxiv.1606.01415,
  title  = {Predictions of canonical wall bounded turbulent flows via a modified $k-\omega$ equation},
  author = {Xi Chen and Fazle Hussain and Zhen-Su She},
  journal= {arXiv preprint arXiv:1606.01415},
  year   = {2016}
}

Comments

22 pages, 14 figures