Direct simulation of fluid-structure interaction with Blue

The interaction of multiphase flows with complex solid geometries is directly simulated in {\it Blue} using a direct forcing technique (Fadlun, Verzicco, Orlandi \& Mohd-Yusof, JCP 161 (2000) 35-60) in the broader context of the immersed boundary method. This capability has recently been introduced in {\it Blue} which is a solver for massively-parallel simulations of fully three-dimensional multiphase flows. Arbitrary solid shapes can be constructed or introduced in CAD format. These solid objects can then be treated as either static, in forced translational and/or rotational motion or in fully free motion with full two-way coupling to the fluid phases. We study the benchmark case of a simple solid sphere plunging into a liquid pool. In addition we present examples of more complex moving solid objects and their interaction with liquid-gas free-surfaces.