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A time-splitting pressure-correction projection method for complete two-fluid modeling of a local scour hole
International Journal of Sediment Research ( IF 3.6 ) Pub Date : 2020-03-02 , DOI: 10.1016/j.ijsrc.2020.02.004
Kambiz Farahi Moghadam , Mohammad Ali Banihashemi , Peyman Badiei , Ali Shirkavand

A two-dimensional vertical (2DV), Eulerian two-phase model or complete two-fluid model of the free surface flow was developed to simulate water-sediment flow in a local scour hole. In the model, the complete forms of the vertical, two-dimensional, two-fluid Navier-Stokes equations were discretized using a finite volume scheme. This discretization was done based on a standard staggered grid system using a curvilinear network system in compliance with the bed boundaries and water level. At the beginning of the computational cycle, the equations governing the fluid phase were solved based on the two-step projection method with a pressure-correction technique. In the first step, the intermediate fluid velocities were obtained by solving different phases of the momentum equations of the fluid phase using the time-splitting technique. In the second step, pressure was obtained and fluid velocities were updated. In this step a simple discretization method was applied for decreasing the computational complexity. After obtaining all the fluid phase variables at a new time step, the sediment phase momentum equations were solved using the time-splitting technique and sediment velocities were obtained. Then, at the end of the computational cycle, the sediment phase mass equation was solved and the concentrations of both phases were updated. At last, the capacity of the model for simulating of the longitudinal fluid velocity and sediment concentration in a local scour hole was evaluated. Numerical results were found to be in good agreement with experimental data.



中文翻译:

用于局部冲刷孔的完整二流体建模的时分压力校正投影方法

建立了二维垂直(2DV),欧拉两相模型或自由表面流的完整两流体模型,以模拟局部冲刷孔中的水-泥沙流。在模型中,使用有限体积方案离散了垂直,二维,双流体Navier-Stokes方程的完整形式。离散化是基于标准的交错网格系统完成的,该系统使用曲线网络系统,并遵循床边界和水位。在计算周期的开始,基于两步投影法和压力校正技术,求解了控制液相的方程。第一步,通过使用时间分割技术求解流体相动量方程的不同相来获得中间流体速度。第二步 获得压力并更新流速。在这一步骤中,采用了一种简单的离散化方法来降低计算复杂度。在获得新的时间步长的所有流相变量后,使用时间分割技术求解了沉积物相动量方程,并获得了沉积物速度。然后,在计算周期结束时,解决了沉积物相质量方程式,并更新了两相的浓度。最后,评估了该模型在局部冲刷孔中模拟纵向流体速度和沉积物浓度的能力。数值结果与实验数据吻合良好。在这一步骤中,采用了一种简单的离散化方法来降低计算复杂度。在获得新的时间步长的所有流相变量后,使用时间分割技术求解了沉积物相动量方程,并获得了沉积物速度。然后,在计算周期结束时,解决了沉积物相质量方程式,并更新了两相的浓度。最后,评估了该模型在局部冲刷孔中模拟纵向流体速度和沉积物浓度的能力。数值结果与实验数据吻合良好。在这一步骤中,采用了一种简单的离散化方法来降低计算复杂度。在获得新的时间步长的所有流相变量后,使用时间分割技术求解了沉积物相动量方程,并获得了沉积物速度。然后,在计算周期结束时,解决了沉积物相质量方程式,并更新了两相的浓度。最后,评估了该模型在局部冲刷孔中模拟纵向流体速度和沉积物浓度的能力。数值结果与实验数据吻合良好。利用时间分裂技术求解了泥沙相动量方程,得到了泥沙速度。然后,在计算周期结束时,解决了沉积物相质量方程式,并更新了两相的浓度。最后,评估了该模型在局部冲刷孔中模拟纵向流体速度和沉积物浓度的能力。数值结果与实验数据吻合良好。利用时间分裂技术求解了泥沙相动量方程,得到了泥沙速度。然后,在计算周期结束时,解决了沉积物相质量方程式,并更新了两相的浓度。最后,评估了该模型在局部冲刷孔中模拟纵向流体速度和沉积物浓度的能力。数值结果与实验数据吻合良好。

更新日期:2020-03-02
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