刚性淹没双层植被明渠水流紊流特性研究

文章采用标准 紊流模型，结合雷诺平均Navier-Stokes方程，对刚性淹没双层植被明渠水流特性进行了研究。计算所得的流速值与实测值吻合良好，表明计算方法可行。进而根据空间及时间的双平均理论，给出了双平均条件下的明渠流速，雷诺应力及紊动能分布，并对紊动能平衡方程中的各项进行了分析。结果可以看出，刚性双层淹没植被作用下，垂向流速分布曲线由三个拐点将其划分为四个区域；雷诺应力及紊动能分布在植被顶端明显增强，高植被顶端各项值均大于低植被顶端相应值；紊动能平衡方程中的紊动耗散项及压力耗散项在紊动能平衡方程中起着主导作用；植被顶端区域产生的涡，通过喷射和扫掠作用使其附近水体发生质量及动量交换。

Turbulence Structure of Open Channel Flow Through Double Layer Rigid Submerged Vegetation

Standard turbulence model, combined with Reynolds-averaged Navier-Stokes(RANS) equations are used in studying turbulence structure of open channel flow through double layer rigid submerged vegetation. The calculated velocity distributions are in good agreement with test data, which proves the validity of the computational method. The velocity distribution, Reynolds stress and turbulent energy distribution are derived by using the double-averaged(in space and in time) hydrodynamic equations. The vertical velocity distribution is divided into four regions by three turning points. Reynolds stress and turbulent energy distribution dramatic increases at each top of the vegetation layer, maximum value can be found near the taller vegetation. Turbulent dissipation and pressure dissipation plays a leading role in the balance of turbulent energy equation. The vortex that generated at the top of vegetation result in a massive mass and momentum transfer through ejection and sweeps.