Fluid structure interaction in fully collapsible tubes

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.

The main goal of the developed theory is to formulate the biomechanical conditions (geometrical dimensions, viscoelastic properties of veins and blood fluid flow conditions) at which an unstable behavior or even the vein collapse can occur. The above problems are numerically modeled by the finite element method. The weak formulation of the tube deformation is based on the virtual work principle. The mixed formulation of the finite element method with the separately interpolated pressure is used for the structure. The strong coupling of both structure and fluid solvers allow us to simulate self-induced large deflection oscillations of the tube. Provided that the Neo-Hook’s material model was applied the analytical formula for the collapse conditions was found. It was proved that for the brain vein contraction about 5%, the vein collapse can occurs even under normal physiological condition – the angiosynizesis. The fluid structure interaction is studied experimentally on the special experimental line. The fluid structure phenomenon is investigated both for the continuous and pulsating flow and it is evaluated by a non-invasive optical. The method is based on optical measurements of radial displacement of the pulsating tube wall. The simultaneous clinics observation (histological findings), in vitro experiments and numerical modeling gives sufficient data to predict biomechanical conditions of the angiosynizesis.