Hydrodynamic education with rheoscopic fluid

¹ Department of Power System Engineering, University of West Bohemia in Pilsen, Univerzitní 22, 306 14 Pilsen, Czech Republic
² Doosan Škoda Power, Tylova 57, 301 28 Pilsen, Czech Republic
³ Institute of Thermomechanics, Czech Academy of Sciences, Dolejškova 5, 182 00 Prague, Czech Republic

^* e-mail: dudad@kke.zcu.cz
^** e-mail: uruba@kke.zcu.cz

Published online: 28 June 2019

Abstract

We present a educational poster supporting the subject „Mechanics of fluids I“, which the students evaluate to be difficult mainly due to abstractness. Our goal is to show in vivo the behavior, especially the non-linearity, of various flows transiting into turbulence. The fluid motion is visualized by using the rheoscopic fluid, which consist of water and the dust of mica, whose particles are longitudinal and shiny resulting into easily observable reflections, when the particles coherently orient along the maximum stress. This happens mainly in shear layers, e.g. at the boundary between vortex core and envelope. An example of flow transiting into turbulence is the Taylor-Couette flow between two concentric cylinders, which with increasing Taylor number passes through various regimes from fully laminar bearing flow through the Taylor vortex flow (TVF) and later Wavy vortex flow (WVF) up to Turbulent Taylor vortices regime (TTV) and, finally, the regime of featureless turbulence.