Pebble bed gas-cooled nuclear reactors are a type of small modular reactor (SMR), and is one of many designs currently being developed for deployment around the world in the next two decades. As with all nuclear reactor designs, stringent safety requirements are set before these systems may be licensed for commercial operation. As a part of this design process, engineers are performing numerical simulations of the fluid flow through these reactor cores with varying fidelity. These calculations range from 1D system-scale simulations up to fully resolved direct numerical simulation (DNS) of the fluid flow.
In the video, we illustrate the complexity of flows through domains of closely packed spheres, i.e. pebble beds, by performing DNS calculations on a series of packed sphere domains of increasing complexity. By doing this, we intend to connect classical fluid dynamics problems such as flow over a single sphere, with more practical problems such as the flow through pebble beds.