離散要素モデルによる高分子溶液の乱流抵抗低減の数値シミュレーション

抄録

To investigate the mechanism of drag reduction by dilute addition of polymer in turbulent flows, a direct numerical simulation (DNS) of turbulent channel flow including discrete-element models has been carried out. The influence of polymers is approximated by beads-spring-dashpot model. The number of grid point for fluid turbulence is 64×64×64 and the number of discrete-elements is 250000. The DNS result achieved 15% drag reduction. The viscosity represented by a dashpot, rather than the elongated elasticity by a spring, contributed to the drag reduction. Experimental evidence such as enhancement of streamwise fluctuation, reduction of Reynolds shear stress, increase of streak spacing in the near-wall turbulence was consistently reproduced in our simulation.