Numerical simulation of turbulent flow in microscopic pore scale of pebble bed by large-eddy simulation

Performance of a fusion reactor using pebble bed in its blanket depends on averaged properties such as packing density of the bed. On the other hand, crucial phenomena that affect safety issues, such as blockage of flow area and the outset of a heat spot caused by thermal creep of constituent particles, depend on local properties of the bed. Conventional researches for pebble bed have been done in terms of average operation or coarse graining of the bed and can never capture the above local phenomena. In this study, the pebble bed is not coarse-grained but is treated such that small scale phenomena are treated as they are. Large-eddy simulation is used for simulation of turbulent flow in microscopic pore scale of pebble bed in the frame of the finite element method. The bed is modeled as one with regular configuration of spherical particles and fluid motion in the pore is simulated in detail.