浸入边界法模拟小圆柱对主圆柱涡脱落的抑制

使用浸入边界法研究了小圆柱对主圆柱涡脱落的抑制.方法中使用非贴体笛儿尔网格,易于处理包含复杂边界的流动问题.采用离散附加力直接加入边界条件方法对虚单元进行重构,使边界条件在浸入边界上精确满足.使用隐式分步法解二维非定常不可压Navier-Stokes方程,通过速度和压力解耦提高计算效率.数值模拟单圆柱绕流及不同位置小圆柱和主圆柱的流动干扰,通过分析流场涡结构和升、阻力系数,得到小圆柱对主圆柱涡脱落的延迟和抑制作用.计算结果与已有实验结论和数值结果对比,计算误差不超过5%,说明浸入边界法可以简单有效地处理圆柱涡脱落抑制这类流动干扰问题.

Suppression of vortex shedding around main circular cylinder by another small control cylinder using immersed boundary method

Based on the immersed boundary method, the suppression of vortex shedding around a main circular cylinder by another small control cylinder was numerically studied. The flow was computed on non-body conformal Cartesian grid, which was suitable for problems with complex boundaries. The discrete forcing direct boundary condition imposition could impose boundary condition on immersed boundary accurately. An implicit fractional step method on collocated grid was used to solve the two-dimensional unsteady incompressible Navier-Stokes equations, and improve its computational efficiency by decoupling of velocity and pressure. The numerical simulations included the flow over a cylinder and the flow interference between a main circular cylinder and another small control cylinder located at two different positions. From analysis on the vortex structure of flow fields and the lift and drag coefficients, the delay and complete suppression of vortex shedding behind the main circular cylinder was found. All the calculated results agreed well with the previous experiment and numerical results, with the error not exceeding 5%. This indicates the immersed boundary method could be simply and efficiently used for numerical simulation on suppression of vortex shedding.