Simulation of Geophysical Fluid Flow Under Microgravity - 2 (Geoflow-2) - 12.07.16
Simulation of Geophysical Fluid Flow under Microgravity - 2 (Geoflow-2) studies heat and fluid flow currents within the Earth's mantle. Geoflow-2 aims to improve computational methods that scientists and engineers use to understand and predict the processes in the Earth's mantle that lead to volcanic eruptions, plate tectonics and earthquakes. Science Results for Everyone
Following on Geoflow-1, this experiment investigated temperature-dependent fluid viscosity properties using numerical simulations in three-dimensions. The flow patterns differed between Geoflow-1 and Geoflow-2. In Geoflow-1, researchers observed a sheet-like thermal flow and successfully reproduced simulated convection patterns. In Geoflow-2, plume-like structures were observed. Numerical simulations do not yield this type of solution for the low viscosity contrast realized in the experiment, but using a viscosity contrast of two orders of magnitude or higher, scientists could reproduce the Geoflow-2 patterns. They concluded that nonlinear effects shift the effective viscosity ratio. Experiment Details
Christoph Egbers, Ph.D., Brandenburg University of Technology, Cottbus, Germany
Birgit Futterer, Brandenburg University of Technology, Cottbus, Germany
Philippe Beltrame, Ph.D., Max-Planck-Institut fur Physik Komplexer Systeme, Dresden, Germany
Pascal Chossat, Centre International Rencontres Mathematiques, Marseille, France
Frederik Feudel, University of Potsdam, Potsdam, Germany
Rainer Hollerbach, Ph.D., Institute of Geophysics, Zurich, Switzerland
Innocent Mutabazi, University of Le Havre, Le Havre, France
Laurette S. Tuckerman, Ph.D., Ecole Superieure de Physique et de Chimie Industrielles, Paris, France
D Breuer, Institute of Planetary Research, Berlin, Germany
J. Srulijes, France
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
September 2010 - September 2012
- Simulation of Geophysical Fluid Flow Under Microgravity - 2 (Geoflow-2) investigates the flow of a fluid between two rotating spheres, where the smaller sphere sits inside of the larger sphere. The spheres rotate about a common axis under the influence of a simulated gravitational force field (the gravity field simulated with an applied electric field).
- Geoflow-2 differs from Geoflow-1 in that the fluid in Geoflow-2 is designed to change its inherent resistance to flow (viscosity) when the temperature of the fluid changes.
- This experimental design will help to show how fluids flow in a configuration similar to the one found in the liquid nuclei of planets.
- Understanding the fluid flow in this experiment will not only enhance computer models in predicting earthquakes and volcanic eruptions, but also could be useful in a variety of engineering applications, such as improving spherical gyroscopes and bearings, and centrifugal pumps.
Operational Requirements and Protocols
Decadal Survey Recommendations
Information Pending^ back to top
Using a spherical geometry set-up, experiments on electro-hydrodynamic driven fluid convection have been performed for both temperature-independent (GeoFlow-I) and temperature-dependent fluid viscosity properties (GeoFlow-II) with a measured viscosity contrast ratio of up to 1.5. Numerical simulations in three-dimensional spherical geometry were also carried out to reproduce the results obtained in the GeoFlow experiments. Observed flow patterns were distinctly different between these 2 experiments. A sheet-like thermal flow was seen in GeoFlow-I. For this case, convection patterns have been successfully reproduced by three-dimensional numerical simulations using 2 different and independently developed simulation programs. By contrast, plume-like structures were observed with GeoFlow-II. Interestingly, numerical simulations do not yield this type of plume for the low-viscosity contrast. However, using a viscosity contrast of 2 orders of magnitude (or higher) in the numerical modelling, the science team could reproduce the patterns seen in GeoFlow-II. Based on this result, it is concluded that nonlinear effects shifted the effective viscosity ratio.^ back to top
Ground Based Results Publications
Futterer B, Dahley N, Koch S, Scurtu N, Egbers C. 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. Acta Astronautica. 2012; 71: 11-19. DOI: 10.1016/j.actaastro.2011.08.005.
Ezquerro Navarro JM, Fernandez JJ, Rodriguez J, Laveron-Simavilla A, Lapuerta V. Results and experiences from the execution of the GeoFlow experiments on the ISS. Microgravity Science and Technology. 2015 February; 27(1): 61-74. DOI: 10.1007/s12217-015-9413-5.
Geoflow-2 models convection in the Earth's mantle (Image courtesy of Brandenburgische Technische Universität).
+ View Larger Image
Geoflow-2 fluid cell assembly: core unit of the experiment. The inner sphere is just visible inside outer glass. Image courtesy of Brandenburgische Technische Universität.
+ View Larger Image
NASA Image: ISS029E006885 - View of printed sign saying "DO NOT TOUCH. EXPERIMENT RUNNING" in front of the FSL (Fluid Science Laboratory) rack taken by the Expedition 29 crew.
+ View Larger Image