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Project Progress

Co-Investigator Christophe Sotin has prepared a numerical code to simulate the formation of liquids in the Titan subsurface. The code has been set up with Titan parameters and the first 3D calculations have been run (Figure 1). The major difficulty is to properly handle the viscosity variations. Right now we have reached steady state flow for viscosity variations of one order of magnitude. The spatial mesh has to be adapted such that viscosity variations across one grid volume do not exceed a threshold above which convergence is not ascertained. The thickness of the ice layer is fixed to 50 km and the top and bottom boundaries are isothermal boundaries. The geometry is driven by the instability of hot plumes forming at the lower thermal boundary layer. The closer we get to a realistic activation energy of 50 kJ/mole, the larger the mean temperature of the convective layer. The size of the plumes decreases with increasing values of the activation energy. It is expected that a realistic case will be achieved by December 2009. The results will be used to map places where ices such as clathrates and ammonia hydrates can melt in the upwelling plumes.