Three Dimensional Modeling of Flow Induced Vibration for an Elastic Cylinder in a Cross Flow
A fully three dimensional flow induced vibration problem for an elastic cylinder in a cross flow has been calculated. The cylinder is treated as a flexible cable and is allowed to freely vibrate at the streamwise and transverse directions while the two spanwise ends are tightly fixed at two end plates. The fluid flows are governed by the three dimensional unsteady Navier-Stokes equations that are numerically solved by a finite volume method on unstructured moving grid. The cable displacement components at the streamwise and transverse directions are described by linear wave equations of second order. The coupling between fluid motion and cable response at each time step is treated in an iterative way so that the fluid and structure coupling can be accounted for properly in affordable PC resources. Calculations are presented in this work for the first two synchronization states, i.e., St =f 0 and St = 2.0f 0 in which St and f 0 are the dimensionless shedding frequency of according stationary cylinder and fundamental natural frequency of cable. Mass ratio m = 10, cylinder aspect ratio a = 16 and Reynolds number Re = 100 are selected at which the wake flow has been proven to be three dimensional laminar. Numerical results show that the cross flow locks the St = f 0 cable motion into the first vibration mode while locks the St = 2.00 f 0 cylinder motion into the second vibration mode.
KeywordsFinite Volume Method Cross Flow Fluid Load Synchronization State Elastic Cylinder
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