波流环境中射流的大涡数值模拟

Large eddy simulation of a jet in wave-current environment

采用大涡模拟方法(LES)对波流环境中的垂向圆管射流进行了数值模拟。出口边界采用人工海绵层加零梯度条件以减小数值反射,且保证自由出流;入口边界分别采用线性叠加和非线性叠加的波流边界条件,通过与物理实验数据对比发现,采用非线性叠加的边界条件时模拟精度更高。数模结果表明,在波浪和水流共同作用下,射流体上部出现了较为明显的"水团"现象,射流平均速度矢量较纯流环境中更靠近底床,这与前期实验观察的结果一致。

Numerical simulation of a vertical round jet in wave-current environment was performed using the large Eddy Simu- lation （LES） method. The zero-gradient condition combined with a sponger layer was imposed at the outflow boundary to reduce the numerical reflection. The linear and non-linear superposition of wave and current boundary conditions were adopted at the inflow boundary respectively. The latter was proved to be of higher precision by comparison of the velocity profiles with the experimental data. Numerical results show that under the combined effect of wave and current, an apparent ＂water masses＂ phenomenon appears on the upper part of jet body and the jet velocity vectors are deflected closer to the bottom than that in a pure current environment, which is consistent with the previous experimental observations.