Impact of Liquid Seal Pr and Sc on the Double-Diffusive Marangoni Convection in Open Rectangular Cavity

The numerical simulation of double-diffusive Marangoni convection in a two-layer immiscible rectangular cavity with free surface is carried out by D2Q9 Lattice Boltzmann method(LBM). In this work, the surface Reynolds number Re₂, interface Reynolds number Re₁, low layer Prandtl number Pr₁ and Schmidt number Sc₁ are fixed at 600, 300, 1.0 and 100, respectively. The spectrum analysis and the phase-space reconstruction are introduced to determine the flow pattern. By comparing with the single-layer system, the results show that the liquid seals can effectively suppress the double-diffusive Marangoni convection at the lower layer. The stability of double-diffusive Marangoni convection are affected by physical property of liquid seals. When the top layer Schmidt number Sc₂=100 and Prandtl number Pr₂=0.4~10.0, the convective modes are two-frequency quasi periodic, and the frequencies f₁ and f₂ decrease with the increasing of Pr₂, which indicates that the system stability increases. When Pr₂=1.0 and Sc₂=20~100, the oscillatory frequencies increase as Sc₂ increases, and the flow pattern will transit from periodic model to the quasi-periodic model again, which implies the system stability decreases.