Fuel tank slosh simulation. Computational fluid dynamics (CFD) supercomputer simulation showing free surface waves for a high slosh amplitude inside a fuel tank. Propellant slosh can disturb the stability of rockets. The simulation points to three physical effects controlling the increase of slosh damping: recirculation zones inside the liquid where small eddies enhance viscous damping; energy cascades from the first surface mode to the higher modes; and kinetic energy loss due to surface breakup. This simulation, produced by NASA's Pleiades supercomputer, was featured at the SC13 supercomputing conference in November 2013.