A numerical method for calculating the flow-induced vibration of the microstructure profiler

The flow-induced vibration is the determinant factor of the low end detection limit of microstructure profiler detecting the dissipation rate of turbulence kinetic energy. In the present investigation, a numerical method is proposed to calculate the flow-induced vibration of the microstructure profiler. In the method, the fluid-solid coupling calculation is conducted using ANSYS-CFX codes. The active force generated by the vortex shedding during the profiler sinking is first calculated using the CFX code. By applying the active force to the profiler in the environment of ANSYS, the vibration frequency and the acceleration of the profiler in horizontal direction are then obtained. To validate the numerical method, sea tests are executed using the free-falling microstructure profiler developed by Tianjin University in the Western Pacific. The acceleration signals of the flow-induced vibration obtained from the numerical method have good agreement with those from the sea tests. The present investigation provides a convenient and effective method to predict the flow-induced vibration and further estimate the low end detection limit of the microstructure profiler in design stage.