Numerical simulation of 3-D Bénard convection with gravitational modulation

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Abstract
In this numerical study, randomly and sinusoidally modulated gravitational fields imposed on three‐dimensional Rayleigh–Bénard convection are investigated in an effort to understand the effects of vibration (G‐Jitter) on fluid systems. The time‐dependent, Navier–Stokes equations and the energy equation with Boussinesq approximations are solved by a semi‐implicit, pseudospectral procedure. An analysis of energy balances indicates that with increasing modulation amplitude, transition from synchronous to relaxation oscillation goes through the subharmonic response. Random modulations are found to be less stabilizing than sinusoidal and are shown to impose local three‐dimensionality on the flow for some parameter ranges both at terrestrial and zero base gravity conditions.