Three-dimensional simulations of water-mercury anticonvection

Anticonvection in a two-layer system of mercury and water is studied using three-dimensional direct numerical simulations with a Fourier-Chebyshev spectral method. The two fluid layers have equal thicknesses and are uniformly heated from above. Interface deformations and surface tension gradients are neglected. The quiescent state is replaced by steady hexagons upon increasing the heating from above. We investigate the destabilization of this primary convective pattern in a small and in a large computational domain upon increasing the temperature difference across the two fluid layers. For the large domain the convection cells become disordered at about twice the critical temperature difference for the onset of convection. The mean interfacial temperature spectrum shows a power-law behavior with an exponent somewhat larger than -4. Convection cells grow in size with increasing temperature difference. Copyright © 2008 Tech Science Press.