竖直上升通道内微气泡湍流流动的数值模拟

为了提高气泡浓度分布预测精度,考虑流体和气泡之间的双向耦合作用,对竖直上升通道内含有微小气泡的湍流流动进行了数值模拟研究。采用直接数值模拟方法模拟流体流动,并用拉格朗日法跟踪气泡受流体和重力作用所产生的运动轨迹。气泡受力包括相间阻力、虚质量力、升力、壁面升力、压力梯度和重力等。数值模拟结果表明,通过加入壁面升力和采用双向耦合方法,可以较准确地预测气泡浓度分布和揭示气泡流动对流体湍流结构的影响。

Numerical Simulation of Upward Microbubble-Laden Turbulent Channel Flow

To improve the predictive accuracy of bubble concentration distribution,numerical study of upward turbulent channel flows laden with microbubbles is carried out and the fluid-bubble two-way coupling interaction is considered.Direct numerical simulation is used for solving the Navier-Stokes equation and Lagrangian approach is used to track the bubble trajectories through the action of forces imposed by the fluid and the gravity.The forces acted on the bubbles are drag,virtual mass,lift,wall lift,pressure gradient,and gravity.Numerical results show that the bubble concentration distribution can be predicted by using the two-way coupling of the fluid and the bubble motion,and adding the wall lift force into the bubble motion equation,and the fluid velocity,turbulence intensity and shear stresses modified by the bubble motions can also be revealed.