Adjoint-based phase reduction analysis of incompressible periodic flows
Adjoint-based phase reduction analysis of incompressible periodic flows
复制标题
DOI：
10.1103/physrevfluids.7.104401
复制
发表时间：
2022-10-06
影响因子：
2.7
通讯作者：
Taira, Kunihiko
中科院分区：
文献类型：
--
作者：
Kawamura, Yoji;Godavarthi, Vedasri;Taira, Kunihiko
我们建立了不可压缩周期性流动基于伴随的相约化分析的理论框架。通过这种基于伴随的方法，我们通过一对向前和向后的直接数值模拟，而不是基于脉冲的方法，需要非常大量的模拟得到时空相位灵敏度字段。基于相位的分析涉及关于周期性变化的基态的扰动分析，因此针对周期性流动的分析而定制。本文给出了考虑流场中的位扰动和涡扰动的周期流的相位描述。目前的相位缩减分析也可以在浸入边界投影法中一致地实现，这便于对任意形状的物体进行分析。我们证明了基于相位的分析的强度周期性流动在圆柱和对称翼型在大迎角。研究了圆柱流中相位修正的临界区域，发现流动分离的位置是最敏感的区域。进一步揭示了攻角和翼型厚度对不同翼型绕流相敏度分布的影响。这种流动的相位是根据升力系数确定的，因此它受到产生升力的涡结构的影响。本框架揭示了相位敏感性和涡旋形成动力学之间的联系。
We establish the theoretical framework for adjoint-based phase reduction analysis for incompressible periodic flows. Through this adjoint-based method, we obtain spatiotempo-ral phase sensitivity fields through a single pair of forward and backward direct numerical simulations, as opposed to the impulse-based method that requires a very large number of simulations. Phase-based analysis involves perturbation analysis about a periodically varying base state and hence is tailored for the analysis of periodic flows. We formulate the phase description of periodic flows with respect to the potential and vortical pertur-bations in the flow field. The current phase-reduction analysis can also be implemented consistently in the immersed boundary projection method, which facilitates the analysis over arbitrarily shaped bodies. We demonstrate the strength of the phase-based analysis for periodic flows over circular cylinder and symmetric airfoils at high incidence angles. The critical regions for phase modification in the cylinder flow are investigated, and the locations of flow separation are shown to be the most sensitive regions. Further, the results reveal the influence of the angle of attack and airfoil thickness on the phase-sensitivity distribution of flows over various airfoils. The phase for such flows is defined based on the lift coefficient, and hence it is influenced by the vortical structures responsible for lift production. The present framework sheds light on the connection between phase sensitivity and vortex formation dynamics.