Direct Numerical Simulation of turbulent mixed convection around a bundle of heated rods at low-Prandtl number

The present work reports an overview of the results of Direct Numerical Simulations performed on the case of fully-developed, mixed convection flow of a liquid metal around a uniformly heated bundle of vertical rods. Finite-Volume computations are performed by an original discretization technique based on the representation of arbitrarily-shaped cylindrical boundaries on a non-uniform Cartesian grid. A domain consisting of four subchannels of a triangular lattice of rods with a pitch-to-diameter ratio P/D = 1.4 is considered as the reference geometry. A single friction Reynolds number value is simulated, namely Reτ = 550. Both forced and mixed convection regimes are investigated, buoyancy effects being introduced by imposing a Richardson number value of Ri = 0.25. A Prandtl number Pr = 0.031 is chosen to represent LBE as the working fluid. Instantaneous snapshots and relevant statistics of the velocity and thermal fields are reported here for the considered case, and integral results are compared against available literature data