【摘要】 建立各向异性三维代数应力紊流数学模型(ASM)克服了各向同性紊流模型的缺点,模拟出顺直河道中次生流现象;与实验成果的比较分析证明了该三维紊流模型有良好的准确性。运用该数学模型对采沙坑周围水流进行分析,结果表明河床上出现采沙坑后不但沿主流会造成纵向涡旋的坑上游缘口冲刷,横断面坑内次生流亦对河床有横向侵蚀,原有流态的变化迫使河床变形调整以趋向新的平衡。运用该数学模型能阐明次生流以及纵向涡旋对河床变形的作用,可模拟分析河道采沙对河床形态调整的影响,对河道采沙的科学决策和管理有积极意义。更多还原

【Abstract】 A 3D anisotopic Algebraic Stress Model (ASM) getting over the shortcoming of isotropic model is established to simulate the turbulencedriven secondary flow in a straight channel. The accuracy of the model is verified by comparing the calculating results with the experimental results. Analyzing the flow around the sand pit on riverbed based on numerical model shows that not only the streamwise flow scours the upstream edge of the sandpit but also the secondary current erodes the transversal part of the cross section. Riverbed adjustment has to be made to a new balance situation due to the change of flow pattern. Based on ASM model, the effect of secondary flow and streamwise flow on riverbed could be illuminated. On the other hand, the influence of sand extraction on the riverbed adjustment could also be analyzed. The numerical model can play a positive role in decisionmaking and management of sand extraction.更多还原