发表机构
University of California, Irvine（加州大学尔湾分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过模拟Re=170的圆柱绕流，发现无滑移条件并非涡量产生或周期性涡脱的必要条件，但对积分流量和涡脱动力学的精确定量预测仍有必要。
AI 中文摘要
传统观点认为无滑移边界条件是涡量产生的必要条件，这可能源于Lighthill涡量产生机制的暗示。然而，Morton（1984）和Terrington等人（2020）的研究主张涡量产生机制独立于无滑移边界条件。为验证这一假设，我们在雷诺数Re=170的层流周期性冯·卡门涡脱 regime 下，对圆柱绕流进行粘性流动模拟，未在壁面施加无滑移条件，而是采用单侧有限差分近似闭合壁面切向速度及其法向导数，因此壁面切向速度由演化的内部解动态确定，而非预先设定。结果显示，三种壁面处理方式（无滑移、二阶单侧近似、三阶单侧近似）下的流动均呈现定性相似的周期性涡脱模式，尽管平均阻力系数、升力系数的均方根值及斯特劳哈尔数与标准无滑移模拟存在差异。更重要的是，边界层外紧邻处的速度分布与标准无滑移模拟高度匹配，且与近似阶数无关。特别地，沿边界层边缘轮廓计算的环量（对应无滑移情形下该层内的总涡量）对壁面处理方式表现出显著的不敏感性。这些结果表明，无滑移条件并非涡量产生或周期性涡脱的必要条件，但它可能仍是积分流量和涡脱动力学精确定量预测所必需的。
英文摘要
It is traditionally believed that the no-slip boundary condition is necessary for vorticity generation, as might be implied by the Lighthill vorticity generation mechanism. However, the investigations of Morton (1984) and Terrington et al. (2020) assert that the vorticity-generation mechanism is independent of the no-slip boundary condition. To investigate this hypothesis, we simulate viscous flow over a circular cylinder in the laminar periodic von Kármán vortex-shedding regime at Re = 170, without enforcing the no-slip condition at the wall. Instead, we close the wall tangential velocity and its normal derivative using one-sided finite-difference approximations. Accordingly, the wall tangential velocity is dynamically determined from the evolving interior solution rather than prescribed. The resulting flows exhibit qualitatively similar patterns of periodic vortex shedding across all three wall treatments (no-slip, second- and third-order one-sided approximations), although the mean drag coefficient, r.m.s. lift coefficient, and Strouhal number differ from those of the standard no-slip simulation. More significantly, the velocity distributions just outside the boundary layer closely match those of the standard no-slip simulation, regardless of the approximation order. In particular, the circulation evaluated along a contour at the edge of the boundary layer, which corresponds to the total vorticity contained within the layer in the no-slip case, is found to be remarkably insensitive to the wall treatment. These results suggest that the no-slip condition is not necessary for vorticity generation or periodic shedding. However, it may still be required for accurate quantitative prediction of the integral flow quantities and shedding dynamics.
Comments14 pages, 5 figures. Supplementary material included as an ancillary file
