Session3: Environmental Hydraulics
Title: NUMERICAL CHARACTERISTICS STUDY ON DELFT3D FOR SIMULATING THE DENSITY FLOW CAUSED BY TEMPERATURE DIFFERENCE IN A RESERVOIR FLUME
Zijun Hu, Yun Lang, Yanbing Zhao, Lei Zhang, Weiwei Guo
Modeling researches on hydrodynamic and temperature characteristics of tributaries of Three Gorges Reservoir (TGR) are generally employed the two-dimensional model of the lateral-averaged N-S equation. In order to obtain a detailed hydrodynamic process, it is necessary to establish a three-dimensional (3D) model. Delft3D (D3D), a widely used software, was utilized to study this issue. Firstly, based on the classical physical model test results conducted by Johnson et al., the numerical characteristics of D3D software in simulating temperature stratified density flow are studied. The σ and z coordinates are compared and analyzed on bed slope and vertical stratification. It found that the coordinate system and the scale of the model mesh in all directions have a impact on the results. The influence of σ and z coordinate system on the result is most related to the longitudinal slope of the river bottom. Considering the characteristics of the change of the Xiangxi River (XXR) bottom and the significant temperature stratification of the internal water body, it is recommended to establish the 3D numerical model of XXR-TGR system by the z-coordinate