Computational Study on the Particle Sedimentation Performance of a Reactor Building Floor Weir by Means of Two-Dimensional Lattice Boltzmann Method

A reactor building floor weir (RBFW) is proposed as a simple as well as an efficient option to sediment particulate debris generated after loss of coolant accident of a nuclear power plant and its performance is computationally studied by means of two-dimensional Lattice Boltzmann Method (LBM) with momentum exchange boundary conditions. After benchmarking against a standard problem of a flow past a cylinder at relatively low Reynolds numbers, the RBFW is simulated for diverse parametric conditions such as height, inclination angle, number of weirs (one or two) and the distance between two weirs. The weir performance is measured by the area of quiescent and/or downward reverse flow region where particles have more chance to sediment. It is found a wake causing reverse downward flow behind the weir mainly contributes to generating the quiescent flow region. And the most effective option in terms of particle sedimentation performance is found to be relatively tall double weirs separated by two weir heights.