Finite Element Simulation of Double Diffusion in a Salt Stratified Fluid Heated from Below
Abstract
Transient double diffusion in a salt stratified fluid confined in a plexiglass rectangular box heated from below was experimentally investigated in a previous study aiming at a better understanding of the physics of a salinity gradient solar pond. In the present work, a finite element simulation of the transient flow dynamics is reported. The Navier-Stokes equations are solved along with the transport equations for energy and salinity. The advection terms are discretized using a spurious oscillation at layers diminishing method and the time discretization is carried out using a second-order backward differencing scheme. The influence of lateral cooling due to heat losses to the surroundings on double diffusion is investigated. The predictions are consistent with Schlieren images and show the time evolution of the interfaces of the convective and diffusive zones. Several physical phenomena, such as the transport across a diffusive interface, the disruption of an interface and the role of lateral cooling on double diffusive convection were observed.