Shear modes in low-prandtl thermal convection
Non-linear, time-dependent numerical simulations of low Prandtl thermal convection are presented. The model is based on a modal expansion and includes a vertical vorticity mode. Shear instability of the primary flow —an hexagonal cell— is proved, and the bifurcation is examined. Two new families of solutions emerge from the bifurcation. One of them, steady, is conjectured to be unstable; the other one, periodic, is examined as a candidate to explain the high frequencies observed in mercury near the transition to time-dependence.
KeywordsNusselt Number Prandtl Number Rayleigh Number Shear Instability Primary Flow
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