Refined similarity hypothesis and asymmetry of turbulence

Abstract

An experimental study of atmospheric turbulence and turbulent pipe flow reveals some deviations from the refined similarity hypothesis (RSH), in addition to those already known. Special emphasis is placed on studying the turbulence asymmetry, as it has proved to be a sensitive indicator of this deviation. It is found that, in spite of good correlation between the velocity increments $u$ and the dissipation field $y,$ the typical amplitude of the latter is appreciably smaller than that of the velocity increments for violent events. In the framework of the RSH, the quantity $V=u/y$ is supposed to be statistically independent of the dissipation. The study shows that there is some weak dependence, manifested at least in a correlation between the sign of $V$ and the amplitude of the dissipation field $y.$ We suggest some modification of the measure in defining the dissipation field, so that the asymmetry can be treated in a self-consistent way in the framework of the RSH.