From isoviscous convective experiment 'GeoFlow I' to temperature-dependent viscosity in 'GeoFlow II'-Fluid physics experiments on-board ISS for the capture of convection phenomena in Earth's outer core and mantle

With the hydrodynamic experiment 'GeoFlow' (Geophysical Flow Simulation) instability and transition of convection between two spherical shells are traced. The flow is driven by a central-symmetry buoyancy force field in microgravity conditions. We performed experiments for a wide range of rotation regimes, within the limits between non- and rapidrotation. Here we focus on the non-rotational convection in an isoviscous experimental fluid as in 'GeoFlow I' and the preparation of 'GeoFlow II', that uses a temperature-dependent viscous fluid. Theoretical predictions on thermal, dielectric and optical performance of the fluid suggest the use of an alkanole, i.e. 1-Nonanol as working fluid for 'GeoFlow II'. Initial ground based experiments demonstrate the influence of the viscosity contrast on fluid flow patterns. Specific results from the 'GeoFlow I' experiment, i.e. steady-state convection above a threshold and transition to chaos, are used as a reference. (C) 2011 Elsevier Ltd. All rights reserved.