Volume 24, Issue 5 (May 2024)
Modares Mechanical Engineering 2024, 24(5): 269-280 |
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Dehghan Manshadi M, Esfahanian V. Stabilization of the Flow Over Cylinder with Time-Varying Disturbance by a Model Reduction Method Using Optimally Time-dependent Modes. Modares Mechanical Engineering 2024; 24 (5) :269-280
URL: http://mme.modares.ac.ir/article-15-74616-en.html
URL: http://mme.modares.ac.ir/article-15-74616-en.html
1- University of Tehran
2- University of Tehran ,evahid@ut.ac.ir
2- University of Tehran ,
Abstract: (854 Views)
The main approach in the study of fluid flow instabilities is the theory of linear stability, which is based on linearizing the governing equations and finding unstable eigenvalues. In many flows, like shear flows, the results of linear stability theory fail to match most experiments. In a linear system, even if all the eigenvalues are stable, the perturbations can lead to instability, if the eigenfunctions are not orthogonal. The transient features of these non-normal dynamical systems, can be described with low-dimensional structures, i.e. a few modes. It is possible to suppress the asymptotic and transient growth by identification of time-dependent modes. In this paper, a method of order reduction based on optimally time-dependent modes has been implemented. This method identifies the growth behavior of disturbances in short and long times. Also, a control algorithm based on the above method has been implemented to stabilize the growth of disturbances. The DNS solution of the flow and the implementation of the reduction and control algorithms is based on the NEKTAR++ open-source solver. At first problem, to validate the solution method, the order reduction and control algorithm has been implemented on the flow over a cylinder with Re=50. At second problem, for the first time, the control algorithm is implemented on the flow over a cylinder subjected to persistent time-varying disturbances. The results show that by applying a control force, the Von-Karman vortices are stabilized and a constant lift is obtained and body vibrations are cancelled.
Article Type: Original Research |
Subject:
Aerodynamics
Received: 2024/04/8 | Accepted: 2024/07/27 | Published: 2024/04/29
Received: 2024/04/8 | Accepted: 2024/07/27 | Published: 2024/04/29
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