大涡模拟在河道平面二维水流模拟中的初步应用

通过丁坝对水流进行控制是航道整治中常用的工程措施,丁坝附近水流呈强紊动特性,大涡模拟相对于基于雷诺方程的时均模型对涡旋有较强的捕捉能力。在直角坐标系的基础上,将大涡模拟中的亚格子应力模型(SGS模型)引入河道水流平面二维数学模型中,通过盒式滤波函数将控制方程进行滤波,大尺度量通过控制方程直接求解,小尺度量借助Smagorinsky提出的亚格子尺度应力模型进行求解。采用空间等步长的正方形网格和交替方向隐式差分法对其控制方程进行离散求解。将模型初步应用于非淹没丁坝绕流的数值模拟中,计算结果表明,该模型对湍流旋涡的捕捉和水深计算较为合理,计算精度可满足工程实践要求。

Application of 2-D LES in river flow simulation

The spur dike is a common structure controlling river flow in channel regulation,around which the flow is characterized by strong turbulence.Comparing with the time-averaged models based on Reynolds equation,the large eddy simulation (LES) has a stronger capability to perform the eddy.The sub-grid-scale (SGS) model,one of LES,is introduced into 2-D river flow model under the Cartesian coordinate to filter the governing equations utilizing the box filter method.The large eddy is computed directly,while the small one is computed with the SGS model by Smagorinsky.The square grid and ADI algorithm is used to discretize the governing equations.The application of the model to simulation of river circumfluence around a non-submerged spur dike shows that the calculated eddies and depth distribution of turbulent flow are in accordance with the observation data and the precision satisfies the engineering requirements.