鱼巢砖渠道的水动力特性数值模拟

Numerical Simulation of Hydrodynamic Characteristics in a Channel with Fish-nest Brisk

为阐明典型生态护岸鱼巢砖对直线型引水渠道水动力特性的影响,基于大涡模拟技术构建了含鱼巢砖渠道的三维水动力数值模型(LES),在流向上使用周期性边界使计算域内水流重复发展,通过水槽试验数据对该数值模型的可靠性进行了充分的验证,并在此基础上利用LES模型模拟了含鱼巢砖渠道的水动力特性。结果表明,鱼巢砖将渠道分为高速主流区和低速鱼巢腔,主流区的时均流向流速约为断面平均流速U0的1.8倍,且在全水深范围内存在连续的涡旋分布;而鱼巢腔内部的时均流速和紊动均处于较低水平,适宜鱼类的栖息及粘性卵的孵化;鱼巢腔口的混合层中存在相对强烈的涡旋结构,不仅显著提高了湍流强度,也是鱼巢腔内外动量交换的主要驱动力。

In order to investigate the impact of typical ecological revetment fish-nest brick on the hydrodynamic characteristics of straight water conveyance channels,a 3-D numerical model(LES)incorporating fish-nest brick was developed using large-eddy simulation technology.Periodic boundaries were employed in the longitudinal direction to allow for the repeated development of water flow within the computational domain.The reliability of the numerical model was extensively validated through experimental data from flume tests.Subsequently,the LES model was used to simulate the hydrodynamic characteristics of channels containing fish-nest brick.The results indicate that the fish-nest brick divide the channel into a high-speed main flow region and a low-speed fish-nest cavity.The time-averaged flow velocity in the main flow region is approximately 1.8 times the cross-sectional average flow velocity(U_0),and a continuous distribution of vortices exists throughout the entire water depth range.Conversely,the time-averaged flow velocity and turbulence within the fish-nest cavity are at relatively low levels,making it suitable for fish habitat and the hatching of adhesive eggs.The mixing layer at the mouth of the fish-nest cavity exhibits relatively strong vortex structures,which significantly enhances turbulence intensity and services as the primary driving force for momentum exchange between the interior and exterior of the fish-nest cavity.