# The stagnation point von Kármán coefficient - Physics > Fluid Dynamics

The stagnation point von Kármán coefficient - Physics > Fluid Dynamics - Download this document for free, or read online. Document in PDF available to download.

Abstract: On the basis of various DNS of turbulent channel flows the following pictureis proposed. i At a height y from the y = 0 wall, the Taylor microscale\lambda is proportional to the average distance l s between stagnation pointsof the fluctuating velocity field, i.e. \lambday = B 1 l sy with B 1constant, for \delta u << y \lesssim \delta. ii The number density n s ofstagnation points varies with height according to n s = C s y +^{-1} -\delta u^3 where C s is constant in the range \delta u << y \lesssim\delta. iii In that same range, the kinetic energy dissipation rate per unitmass, \epsilon = 2-3 E + u \tau^3 - \kappa s y where E + is the total kineticenergy per unit mass normalised by u \tau^2 and \kappa s = B 1^2 - C s is thestagnation point von K\-arm\-an coefficient. iv In the limit of exceedinglylarge Re \tau, large enough for the production to balance dissipation locallyand for -

Author: ** Vassilios Dallas, J. Christos Vassilicos, Geoffrey F. Hewitt**

Source: https://arxiv.org/