Analysis of Vortex Shedding from Bridge Decks Based on Revised Frozen Turbulence Hypothesis

Abstract:

Periodic Vortex shedding from the structures coincides with the periodic forces on the structures.The vortices in the downstream of the structures can be detected by the method of snapshot proper orthogonal decomposition(POD)whether they can be seen obviously or not.The method in this paper combines the method of snapshot POD and small eddy decomposition methods together with part of the frozen turbulence hypothesis.The vortex shedding frequency can be obtained based on one-single-time velocity map alone through which the Strouhal number of the structure can be derived.Numerical simulation was done based on the examples of the square cylinder and twin box bridge deck.The results show the error is rather small of the strouhal number with that through the Fourier transform of the lift force coefficient,implying that the method is practicable.