Experimental evaluation of Kolmogorov's first similarity hypothesis for shear-dependent viscosity fluids

Abstract

We experimentally investigate the applicability of Kolmogorov's first similarity hypothesis to shear-dependent viscosity fluids. We assess whether dissipative range statistics exhibit a self-similar behavior in nearly homogeneous and isotropic turbulence, using stereo particle image velocimetry in aqueous Carbopol solutions across two concentrations and a range of forcing conditions. We observe that, when normalized by the mean viscosity and mean dissipation rate, second- and third-order structure functions collapse across the different experimental conditions and exhibit functional forms compatible with classical Newtonian results. These observations are in general agreement with the recent numerical results of Rosti [J. Fluid Mech. 1012, R5 (2025)], who proposed that Kolmogorov's similarity hypotheses can be extended to shear-thinning fluids by considering dissipation scales based on the mean viscosity, the mean dissipation rate, and the flow index.