An extended Boussinesq theory for interfacial fluid mechanics

Abstract Boussinesq theory can model quite accurately viscous flows that involve multiple fluids with interfaces between them, so long as there is not much difference the densities of various fluids. However, approximation generally poor when density ratio large. Here, we propose an Extended approximate equation, allows for large ratios, while still remaining straightforward to implement. Examples are given planar Rayleigh–Taylor instability, where and novel models compared predictions SPH fluid dynamics code, confirm this approach.