Finite time Lagrangian analysis of an unsteady separation induced by a near wall wake
Finite time Lagrangian analysis of an unsteady separation induced by a near wall wake
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近壁尾流引起的非稳态分离的有限时间拉格朗日分析
DOI：
10.1063/1.3459154
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发表时间：
2010
影响因子：
4.6
通讯作者：
L. Brizzi
中科院分区：
文献类型：
--
作者：
Tony Ruiz;J. Borée;T. T.Tran;C. Sicot;L. Brizzi
根据Lekien和Haller提出的滑移边界上的非定常流分离的拉格朗日理论[“滑移边界上的非定常流分离”，Phys.Fluids 20，097101（2008）]，我们使用有限时间拉格朗日分析，以便在显著的雷诺数下在近壁障碍物下游产生大规模的非定常流分离。大尺度流动分离是指在障碍物的尺度上，流体和涡量在壁面附近的喷射。事实上，虽然在墙上的分离点是没有空间解决的高速粒子图像测速测量，自由滑移边界条件之前，在近壁区域使用有限时间李雅普诺夫指数导出不稳定的流形。对于这种湍流，为了讨论非定常气动力和分离区湍流的相对贡献，给出了条件统计。相应分离点的动力学与由该非定常湍流引起的脉动壁压具有非常清楚的联系。遵循Lekien和Haller提出的滑移边界上的非定常流分离的拉格朗日理论[“滑移边界上的非定常流分离”，Phys.Fluids 20，097101（2008）]，我们使用有限时间拉格朗日分析以导出大尺度，在显著雷诺数下，近壁障碍物下游的非定常流动分离。大尺度流动分离是指在障碍物的尺度上，流体和涡量在壁面附近的喷射。事实上，虽然在墙上的分离点是没有空间解决的高速粒子图像测速测量，自由滑移边界条件之前，在近壁区域使用有限时间李雅普诺夫指数导出不稳定的流形。对于这种湍流，为了讨论非定常气动力和分离区湍流的相对贡献，给出了条件统计。相应的分离点的动力学特性有很清楚的...
Following the Lagrangian theory of unsteady flow separation on slip boundaries proposed by Lekien and Haller [“Unsteady flow separation on slip boundaries,” Phys. Fluids 20, 097101 (2008)], we use finite time Lagrangian analysis in order to educe large scale, unsteady flow separation downstream a near wall obstacle at a significant Reynolds number. By large scale flow separation, we mean here the ejection of fluid and vorticity outside a neighborhood of the wall at the scale of the obstacle. Indeed, while the separation point at the wall is not spatially resolved by the high speed particle image velocimetry measurements, free-slip boundary conditions are applied before educing unstable manifolds in the near wall region using finite time Lyapunov exponents. For this turbulent flow, conditional statistics are presented in order to discuss the relative contributions of the unsteady aerodynamics and of the turbulence in the separation region. The dynamics of the corresponding separation point has a very clear link with the fluctuating wall pressure induced by this unsteady turbulent flow.Following the Lagrangian theory of unsteady flow separation on slip boundaries proposed by Lekien and Haller [“Unsteady flow separation on slip boundaries,” Phys. Fluids 20, 097101 (2008)], we use finite time Lagrangian analysis in order to educe large scale, unsteady flow separation downstream a near wall obstacle at a significant Reynolds number. By large scale flow separation, we mean here the ejection of fluid and vorticity outside a neighborhood of the wall at the scale of the obstacle. Indeed, while the separation point at the wall is not spatially resolved by the high speed particle image velocimetry measurements, free-slip boundary conditions are applied before educing unstable manifolds in the near wall region using finite time Lyapunov exponents. For this turbulent flow, conditional statistics are presented in order to discuss the relative contributions of the unsteady aerodynamics and of the turbulence in the separation region. The dynamics of the corresponding separation point has a very clear...