FAST PLUMEHEADS - TEMPERATURE-DEPENDENT VERSUS NON-NEWTONIAN RHEOLOGY

In a series of two-dimensional Cartesian simulations with high resolut ion, on the order of 2 km, we have compared for the same effective Ray leigh number, around 10(6), the dynamics between Newtonian and non-New tonian theologies. A viscosity contrast due to temperature of 1200 has been employed throughout with surface dissipation numbers varying bet ween 0.05 and 0.2. Peak velocities for non-Newtonian plumes are at lea st 50 times faster than the peak Newtonian velocities and reach magnit udes in excess of m/yr. Upon impinging the surface, plume head structu res of the non-Newtonian rheology contain much greater complexity in t he thermal-mechanical structure than for Newtonian plumes.