DNS study of fusion reactor dust particle mobilization induced by a transonic jet incoming in a vacuum container

The flow induced motion of wall deposited particles is highly linked with the instantaneous fluid structures. Here we perform a two-phase flow DNS to analyze the resuspension of solid particles from a surface hit by a transonic jet into a low pressure container in conditions similar to those which occur in a fusion reactor vacuum vessel during a Loss of Vacuum Accident (LOVA). The initial condition of pressure and temperature were set to 49.5 mbar and 373 K, with a Reynolds number of 3300 on a 512 512 512 grid properly refined in regions where high gradients are present. The Thornton and Ning impact/adhesion model is adopted, whereas an advanced resuspension model, which also takes into account the dynamics (rolling and sliding) of particles at the wall, is here implemented. The initial deposited particles follow a log-normal distribution with a count median diameter of 2.21 μm, geometric standard deviation of 2.93 and constant density of 8527 kg/m3. It has been found that the resuspension phenomenon mostly affect particles of the biggest diameters. Moreover, the jet-deposit interaction is for the most part confined within a circumference around the jet of radius equal to the jet diameter