Simulating compositional convection in the presence of rotation by lattice Boltzmann model

In most practical situations, compositional convection accompanies rotation due to the nature or artificial controls. For simplicity, usually cylindrical coordinates are used for simulating such axisymmetric convectional flows. However, to date the investigation on this field is quite sparse. In this paper a simple LB model is employed to reveal the characteristics of such flows. In the present model, the governing equations for velocity, temperature and concentration fields all are solved in the same fashion. Even with a coarse grid resolution, the present model still works well for rotationally compositional convection with high Rayleigh number and relatively high Lewis number. With the aid of this model, two different kinds of nontrivial compositional convection accompanying rotation, namely the compositional convection in a rotating annulus with horizontal temperature and vertical solutal gradients and that with opposing temperature and concentration gradients, are investigated. Especially, the latter is studied in detailed for the first time. It is found that due to the presence of rotation, the convective motion will be suppressed, for both situations. However, the former is more sensitive to the effect of rotation. For the latter, secondary flow will emerge when the Taylor number is big than 5.68 × 107 and the oscillatory flow is easier to emerge than its irrotational counterpart when the ratio of buoyancy forces approaches to unity. Moreover, the Galilean invariance and its influence on the present model are discussed.