Simulation of low-Re pulsatile flow through bare 5×5 square arrayed rod bundles

摘要

The extra momentum induced by tides and waves on floating systems perturbs their thermal-hydraulics characteristics. Pulsatile flow through rod bundles with pitch-to-diameter = 1.326 and width-to-diameter = 1.268 has been simulated to study the effect of pulsation on time-averaged and transients parameters. The Reynolds Stress Model reported better agreement with preliminary experimental data. The phase lag between the velocity and pressure drop with an increase in the amplitude of pulsation. Time-averaged friction resistance also increases with an increase in the intensity of oscillation. The effect of flow pulsation on a cycle is pronounced in the lateral velocity. The normal A-Re trend is reversed at the onset of deceleration and acceleration in the cycle. Pressure fluctuations are more intense during acceleration and the pressure field is uneven on the rod surfaces. There are also intense velocity fluctuations and high turbulence intensities on the rod surfaces. These findings show that the effects of extra momentum that will be induced on floating systems intended for an ocean environment should be thoroughly investigated during their safety analysis.