弯道三维水沙数值模拟中推移质输移方向的选取

The effect of choosing bed-load transport direction on bed deformation in channel bends using 3-D flow and sediment transport model

在曲线坐标同位网格下,采用不平衡输沙方程建立了弯道三维水沙数学模型,并考虑了弯道处横坡与纵坡存在对泥沙起动的影响。模型采用有限体积法对方程进行离散,采用与动量插值技术相结合的SIMPLEC算法来进行模型求解。通过弯道试验的计算表明,模型能够有效地模拟出弯道处二次流及河床的冲淤变化情况,实测值与计算值吻合较好。在此基础上,进一步分析了弯道处推移质输移方向选取对冲淤模拟结果的影响,选取推移质输移方向与近底0.08倍水深处流速方向一致时,模拟效果较好。

A 3-D flow and sediment transport model was developed using non-equilibrium sediment transport equations in curvilinear coordinate with collocated grid, in which the effect of bed slope in channel bends on sediment transport is considered. The governing equations for flow and sediment transport were solved using the finite volume method （FVM） and the SIMPLEC algorithm with momentum interpolation. This model is able to predict the secondary flow and bed deformation in channel bends, and the results agree well with experiment data. The choice of bed-load transport direction has obvious influence on the simulated results of bed deformation in channel bends. Good agreements between measured and calculated bed deformation are achieved when the direction of bed-load transport is chosen to be the direction of flow velocity at the position of 0.08h from the bed.