Fluid-Solid coupling in advanced gas-cooled reactor thermohydraulics

The flow inside the under dome section of the Advanced Gas-cooled Reactor has been computed in order to estimate heat transfer coefficient at the dome surface. The fluid simulation is coupled with a heat transfer computation comprising the solid dome and insulation. Three calculations are presented, one LES and two URANS. An elliptic relaxation based method is used in conjunction with an adaptive wall function methodology. This wall treatment allows the model to switch between wall-resolved and wall-model formulations depending on the mesh resolution. The LES results are in better agreement with the frequency response analysis based on plant measurements, whereas the k - epsilon results seem unrealistic. The elliptic relaxation model shows improvement over the standard k - epsilon model but is still far from the LES results.