网格尺寸对河流水动力数值模拟的影响

以涪陵—洛碛水道上的上洛碛至下洛碛河段为研究区域,在测量比尺为1∶1 000的实测河道地形图上建立无结构化三角形网格水动力模型,基于有限体积法求解平面二维水动力方程,研究了在多组相对网格比取值下的模型计算结果变化趋势。研究发现:相对网格比的变化对河滩内计算点的计算结果影响远大于对河槽内计算点计算结果的影响。当相对网格比小于1,河道内水动力模型计算结果变化甚微,尤其是此时河槽内平均相对偏差接近于0;当相对网格比大于1,模型计算结果的平均相对偏差逐渐上升,当相对网格比足够大后开始趋稳,河滩内计算结果的平均相对偏差整体增幅大于河槽。随着相对网格比的增大,不同水深段区域内的水动力模型计算结果平均相对偏差变化程度不同。

Influence of grid size on numerical simulation of river hydrodynamics

In this paper,the reach from the upper Luoqi to the lower Luoqi in the Fuling-Luoqi waterway is the research area.An unstructured triangular mesh hydrodynamic model is established on the measured topographic map of 1:1 000 scale,which is based on the method of volumetric method used to solve the two-dimensional hydrodynamic equation,to study the trend of the calculation results of the model in the multi-group relative grid ratio.It is found that the effect of the relative grid ratio on the calculation results of the calculation points in the flood is much greater than that on the calculation points in the river valley.When the relative mesh ratio is less than 1,the calculation results of the hydrodynamic model in the river have changed little,especially the average relative deviation of the river channel is close to zero.When the relative grid ratio is greater than 1,the average relative deviation of the model calculation results gradually increases.And when the relative grid ratio is large enough to stabilize,the average relative deviation of the calculated results in the flood area is larger than that of the river channel.With the increase of the relative mesh ratio,the average relative deviation of the calculation results of the hydrodynamic model in different water depth areas is different.