矩形沉淀池内悬浮物沉降模拟

Modeling of suspended solid transport in rectangular settling tanks

建立了模拟平流式沉淀池中悬浮物的沉降过程模型,以预测沉淀池的去除率。利用标准k-ε紊流模型,考虑悬浮物沉降引起的水体密度变化,采用非正交同位网格下S IM PLE算法求解水动力和悬浮物沉降的耦合模型,使用了能够反映悬浮物沉降特性的双指数沉速公式,底边界上考虑水流对淤泥的冲刷作用,能够更加真实地模拟沉淀池内水流和悬浮物运动情况。比较各工况下沉淀池去除率,得出的最佳挡板高度与经验值相符,同时利用E.Im am所做物理模型的模拟结果进行验证。结果表明,该数学模型在水流流场和悬浮物浓度分布中均能获得较理想的结果。

A mathematical model was used to simulate the velocity fields and suspended solids transport in rectangular settling tanks. The flow model was coupled with a suspended-sediment transport model through a variable fluid density with the standard k-ε turbulence model. The SIMPLE algorithm with colocated non-orthogonal grids was used to solve the Navier-Stokes equations. With double exponential settling velocity and considering the scour effect on the bottom of the settling tanks, a more reasonobal process was establised. The results predict an optimum baffle height in the settling tanks which agrees well with experience. Tested against the experimental data carried out by E. Imam, the flow field and suspended solids transport predicted by the model agree well with previous measurements.