柔性丝线与下游圆柱相互作用的二维数值模拟研究

基于格子 Boltzmann 方法和沉浸边界法,首先对柔性丝线在均匀来流中的周期性摆动和圆柱绕流进行了二维数值模拟,并将模拟结果已有研究成果进行了对比分析。为提高计算效率和计算精度,采用了多块网格耦合算法,并在圆柱曲边界处采用了较为精确的边界处理方法。通过分析柔性丝线的升阻力系数和末端位移,研究了丝线与下游圆柱间距对丝线摆动和尾流特征的影响,并讨论了雷诺数和柔性丝线质量比对结果的影响。通过数值模拟结果得出:下游刚体的存在对柔性丝线有明显的减阻效果;在一定的参数范围内,由于粘滞作用和涡的相互作用,丝线末端的摆动幅值随间距增大相继出现了减小和变大的现象;雷诺数的增大可以增强丝线运动,而丝线质量比起到了不稳定作用。

TWO-DIMENSIONAL NUMERICAL SIMULATION OF INTERACTION BETWEEN A FLEXIBLE FILAMENT AND A DOWNSTREAM CYLINDER

The problems of the two-dimensional flow pasting a flexible filament and a cylinder are investigated using lattice Boltzmann method and immersed boundary method, and then the numerical results are compared with the results of previous research. To improve computational efficiency and accuracy, multi-block strategy is developed, and boundary treatment method is adopted at the boundary of cylinder. The lift and drag coefficients of filament are analyzed, and then the influence of spacing between filament and cylinder on the wake characteristics and flapping situation of filament is investigated. Furthermore, the effects of Reynolds number and flexible filament quality ratio are discussed. The drag reduction of filament is remarkable because of the downstream cylinder. Within a reasonable parameter range, the displacement of tail decreases and then increases, due to the viscous effects and the interaction of vortices. Increase of Reynolds number can enhance the movements of filament, and the quality ratio demonstrates a role of instability.