Experimental Results in the Turbulent Dissipation Range

An intrinsic feature of turbulence is its scale hierarchy, famously illustrated by Richardson's energy cascade and formalized by Kolmogorov's phenomenological theory in 1941 (K41). One of the key points from K41 is that the smallest scales (below the Kolmogorov length scale) are universal for sufficiently turbulent flows, and only depend on the viscosity and the mean dissipation rate. Nevertheless, little is still known about the dynamics at these scales, mainly due to computational and experimental resolution limitations. We circumvent this problem by performing hot-wire experiments in the Göttingen Variable Density Turbulence Tunnel filled with helium, which is approximately 10 times lighter than air. Varying the density of the gas by setting different pressures and temperatures, we are able to obtain Kolmogorov length scales on the order of the millimeter, and Taylor scale Reynolds numbers between 100 and 300. We present results focused in the dissipation regime, reaching a resolution of 5 times the Kolmogorov length scale for the smaller Reynolds numbers, and compare with prior numerical work.