Application of Sponge Boundary Conditions to Large-Eddy Simulation of Multiple Thermal Plumes
While numerically simulating multiple thermal plumes, instabilities arise at the inflow/outflow/convective (IOC) boundaries due to the inability of IOC boundary conditions to effectively advect the flow structures out of the computational domain. To address this issue, Large Eddy Simulation of multiple thermal plumes is carried out with a novel viscous sponge layer, recently formulated by Pant and Bhattacharya (Comput Fluids 134:177–189, 2016, ). We validate our results with available literature, and we also present the effect of sponge layer on vortex rings (produced by thermal bubbles) traveling at an oblique angle to the outflow boundary. It is concluded from this study that the sponge layer does not appreciably affect the vortex rings outside the layer. The vortex rings do get smoothened out inside the sponge layer, which ensures a smooth convective outflow velocity for the eddies, and leads to stable LES of thermal plumes.
AB acknowledges support from I.I.T. Bombay seed grant (Project Code 12IRCCSG020) for this work.