Characterizing the dynamics of a flexible rod wrapped by transverse repeated ribs subjected to axial flow

This study focuses on the dynamics of a flexible cylindrical structure wrapped by repeated transverse rectangular ribs, in an annular flow geometry, under two boundary conditions: simply supported ends and clamped ends. The dynamics is predicted by linear and nonlinear theories. Based on the linear equation a straightforward nonlinear equation can be derived. A parametric investigation of the effect of the ribs' dimensionless geometry characterized by the pitch-to-height and width-to-height ratios, on the fluid-elastic instability characteristics is considered. The results of the present study indicate a strong dependency between rod instability and rib roughness. The nonlinear model confirms the existence of post critical instability and the reliability of the linear results.