Analysis Of Dynamics Feature Of A Cylinder Subjected To Axial Flow

This paper presents a weakly nonlinear equation of motion which is derived for the simply supported cylinder subjected to axial flow, adding the quadratic terms in the expression of the frictional force. The cylinder is considered to be slender and extensible and flexible. The fluid forces are formulated in terms of several components, for convenience. The dominant, inviscid component is modeled by an extension of Lighthill`s slender body work; frictional hydrostatic and pressure-loss forces are then added to the invicid component. The friction forces are formulated essentially as proposed by Taylor in 1952 and by Triantafyllou and Chryssostomidis in 1989. The nonlinear terms considered here are the quadratic viscous force and the structural nonlinear force induced by the lateral motions of the cylinder.The equation of motion is discretized by the Rite-Galerkin method with the two and three-mode expansions, and the numerical analysis is performed with the discretized equation. Bifurcation diagrams obtained through numerical analysis show that not only the buckling instability may occur as found by linear analysis, a flutter around the trivial equilibrium may exist as well for a high enough flow (as predicted by linear theory).