A parallel implicit hole-cutting method based on background mesh for unstructured Chimera grid

Chang, Xinghua; Ma, Ruixuan; Wang, N.H.; Zhao, Zhong; Zhang, L.P.

doi:10.1016/j.compfluid.2019.104403

Cited by 18 publications

(12 citation statements)

References 23 publications

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“…The overall idea is as follows: the body-fitted grid is generated initially over the fish, which is embedded into a background grid covering the entire computational domain by an implicit hole-cutting (IHC) method. 27 The motion of fish can be decomposed into the deformation in its body coordinate system and the rigid displacement in the inertial system. At each time step, the volume nodes of the body-fitted grid deform with the fish body undulation by a radial basis function (RBF) interpolation method 28 firstly.…”

Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

“…Finally, the overset information between the body-fitted mesh and the background mesh is assembled by the IHC method. 27…”

Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

“…In this step, the surface nodes should be gathered up in the server processor, and then, broadcasted to all the other processors. Find the donor cell of each node. Here, the global-to-local (GTL) parallel searching strategy 27 is used. In the GTL searching process, firstly the coordinates of nodes in all the grid zones are gathered up and broadcasted to all the processors as the “global” nodes.…”

Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

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A numerical simulation method for bionic fish self-propelled swimming under control based on deep reinforcement learning

Lang

Chang

Tian

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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In order to simulate the under control self-propelled swimming of bionic fishes, a coupling method of hydrodynamics/kinematics/motion-control is presented in this paper. The Navier-Stokes equations in the arbitrary Lagrangian-Eulerian framework are solved in parallel based on the computational domain decomposition to simulate the unsteady flow field efficiently. The flow dynamics is coupled with the fish dynamics in an implicit way by a dual-time stepping approach. In order to discretize the computational domain during a wide range maneuver, an overset grid approach with a parallel implicit hole-cutting technique is adopted and coupled with morphing hybrid grids around the undulation body. The motion control of the fish swimming is realized by a deep reinforcement learning algorithm, which makes the fish model choose proper undulation manner according to a specific purpose. By adding random disturbances in the training process of fish swimming along a straight line, a simplified two-dimensional fish model obtains the ability to swim along a specific trajectory. Then in subsequent tests, the two-dimensional fish model is able to swim along more complex curves with obstacles. Finally, the starting process of a three-dimensional tuna-like model is simulated preliminarily to validate the ability of the coupling method for three-dimensional complex configurations. The numerical results demonstrate that this study could be used to explore the swimming mechanism of fishes in complex environments and to guide how robotic fishes can be controlled to accomplish their tasks.

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Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

“…Finally, the overset information between the body-fitted mesh and the background mesh is assembled by the IHC method. 27…”

Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

Section: The Integrated Coupling Methods For Fish Self-propelled Swimmmentioning

confidence: 99%

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A numerical simulation method for bionic fish self-propelled swimming under control based on deep reinforcement learning

Lang

Chang

Tian

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Grid quality influences the numerical accuracy directly, whereas grid generation efficiency is an important factor affecting simulation efficiency. In this work, an automatic dynamic overset grid generation technique with parallel implicit hole cutting is adopted to ensure good grid quality and high efficiency [31,32] during the maneuver.…”

Section: B Computational Model and Dynamic Overset Gridmentioning

confidence: 99%

Numerical Virtual Flight Simulation of Quasi-Cobra Maneuver of a Fighter Aircraft

Wang

Chang

et al. 2021

Journal of Aircraft

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By using a computational-fluid-dynamics-based numerical virtual flight (NVF) simulator, a simplified quasi-Cobra maneuver of a typical third-generation fighter is simulated and the unsteady aerodynamics, such as the dynamic forces and moments and the flow separation, are analyzed preliminarily. The NVF simulator integrates an unsteady Reynolds-averaged Navier-Stokes (RANS) solver on dynamic unstructured/hybrid grids, a rigid-body dynamics solver, and user-defined flight control system. To analyze the complex multiphysics coupling problem, four cases with increasing complexity are studied, including 1) static state simulation; 2) one-degree-of-freedom (1-DOF) forced pitchup; 3) 1-DOF pitchup by open-loop control of the elevators; and 4) three-degree-of-freedom (3-DOF) quasi-Cobra maneuvering. By applying a cosine function open-loop flight control law to the elevators and introducing a simplified vector thrust model, the fighter can pitch up to a high angle of attack from the cruising state, and then it can pitch down quickly, the whole process is similar to a Cobra maneuver. Even though the RANS simulations are not necessarily highly accurate for the large angle of attack, the multidisciplinary application in this work demonstrates the potential of the NVF simulator for the simulations of realistic poststall maneuvers.

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“…Landmann and Montagnac used arbitrarily digital tree and parallel cutting algorithm to accelerate the process of IHC (Cai et al, 2003;Landmann and Montagnac, 2011;Liu et al, 2013;Xu et al, 2013;Wei et al, 2007) presented a chimera overset grid method to get better body-fitted grid and simplify the complexity of grid interpolation. Chang et al (2018) presented a parallel IHC method based on unstructured grid.…”

mentioning

confidence: 99%

A parallel algorithm for chimera grid with implicit hole cutting method

Zhang

et al. 2019

The International Journal of High Performance Computing Applica

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The chimera grid methods have been widely used in the simulation of flow over complex configurations and unsteady moving boundary process. Lee and Baeder presented the implicit hole cutting (IHC) method, which improves the practicability and robustness of chimera grid method. But the excessive time consumption of this method restricts the scalability of parallelism. In this article, based on the parallel implementation of IHC method with structured multi-block grid, the factors which restrict the performance and efficiency are analyzed. Cartesian auxiliary grid is introduced to reduce the communication and computing cost. Finally, test cases are presented to demonstrate the effectiveness of this algorithm, and the calculation and data communication are reduced on the premise of maintaining accuracy.

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A parallel implicit hole-cutting method based on background mesh for unstructured Chimera grid

Cited by 18 publications

References 23 publications

A numerical simulation method for bionic fish self-propelled swimming under control based on deep reinforcement learning

A numerical simulation method for bionic fish self-propelled swimming under control based on deep reinforcement learning

Numerical Virtual Flight Simulation of Quasi-Cobra Maneuver of a Fighter Aircraft

A parallel algorithm for chimera grid with implicit hole cutting method

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