This paper presents a reduced order approach for transient modeling of multiple moving objects in nonlinear crossflows. The Proper Orthogonal Decomposition method and the Galerkin projection are used to construct a reduced version of the nonlinear Navier-Stokes equations. The Galerkin projection implemented in OpenFOAM platform allows accurate impositions of arbitrary time-dependent boundary conditions at the moving boundaries. A modelling technique based on moving domain and immersed boundary techniques is proposed to overcome the challenge of handling moving boundaries due to movements of the multiple objects. The model is demonstrated capable to capture the complex flow fields past one and two oscillating cylinders and the forces acting on the cylinders. Simulation time could be reduced by more than three orders for a small case on a fine mesh as compared to an existing method and could be more for large cases. In general, the simulation time of the reduced model is of order of seconds as compared to hours of the full order Computational Fluid Dynamics models.

中文翻译：

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基于投影的降阶模型，用于模拟多运动物体的非线性流

本文提出了一种降阶方法，用于非线性交叉流中多个移动物体的瞬态建模。使用适当的正交分解方法和伽辽金投影来构造非线性 Navier-Stokes 方程的简化版本。在 OpenFOAM 平台中实现的 Galerkin 投影允许在移动边界处准确施加任意与时间相关的边界条件。提出了一种基于移动域和浸入边界技术的建模技术，以克服由于多个对象的移动而处理移动边界的挑战。该模型被证明能够捕获通过一个和两个振荡圆柱体的复杂流场以及作用在圆柱体上的力。与现有方法相比，细网格上的小案例的仿真时间可以减少三个数量级以上，而对于大案例则可能更多。通常，与全阶计算流体动力学模型的数小时相比，简化模型的模拟时间为秒级。