LARGE AXISYMMETRICAL DEFORMATION OF A CYLINDRICAL-SHELL CONVEYING A VISCOUS-FLOW

Large axisymmetric deformations of collapsible tubes conveying a viscous flow are examined. Geometrically nonlinear Lagrangian shell theory is used to describe the deformation of the tube. The fluid flow is modelled using lubrication theory. The coupled fluid-solid problem is solved numerically using an FEM technique. In order to explain the mechanisms involved in the tube deformation, the effects of bending stiffness, wall shear stress and axial pre-stretch are examined in detail. The dependence of the tube resistance on the volume flux is investigated for two different experimental set-ups (constant pressure at either upstream or downstream end of the collapsible tube). Finally, the exact nonlinear shell theory used in this paper is compared to Sanders' moderate rotation theory and an improvement to his theory is suggested.