Experimental and numerical study on a laminar fluid–structure interaction reference test case

With the rapid development of numerical codes for fluid–structure interaction computations, the demand for validation test cases increases. In this paper we present a comparison between numerical and experimental results for such a fluid–structure interaction reference test case. The investigated structural model consists of an aluminum front cylinder with an attached thin metal plate and a rear mass at the trailing edge. All the structure is free to rotate around the axle mounted in the center of the front cylinder. The modelʹs geometry and mechanical properties are chosen in such a way as to attain a self-exciting periodical swiveling movement when exposed to a uniform laminar flow. Reproducibility of the coupled fluid–structure motion is the key criterion for the selection of the model in order to permit an accurate reconstruction of the results in the time-phase space. The Reynolds number of the tests varies up to 270 and within that range the structure undergoes large deformations and shows a strong nonlinear behavior. It also presents two different self-excitation mechanisms depending on the flow velocity. Hence, challenging tasks arise for both the numerical solution algorithm and the experimental measurements. To account for the two different excitation mechanisms observed on increasing the speed of the flow, results for two different velocities are considered: the first at 1.07 m/s (Re=140) and the second at 1.45 m/s (Re=195). The comparisons presented in this paper are carried out on the basis of the time trace of the front body angle, trailing edge coordinates, structure deformation and the time-phase resolved flow velocity field. They reveal very good agreement in some of the fluid–structure interaction modes whereas in others deficiencies are observed that need to be analyzed in more detail.