Stability Issues of Concentric Pipes Conveying Steady and Pulsatile Fluids

In this paper, we study both the static and dynamic stabilities of submerged and inclined concentric pipes conveying uid. The governing equation for the inner tubular beam is derived under small deformation assumptions. We obtain the dis-cretized dynamical equations using spatial nite diierence schemes. In the case of steady ow, both buckling and utter instabilities are investigated. In the case of pulsatile ow, we compute the eigenvalues of the monodromy matrix derived from the discretized linear system with periodic coeecients, and deduce the dynamical stability information. In addition, for a special case, in which the concentric pipes have the same length, we compare the dynamic stability results with the corresponding solutions obtained with the Bolotin method.