A Three-dimensional Numerical Model of a Critical Flow in a Collapsed Tube
Abstract
The laminar steady flow is computed in a rigid pipe with wall configuration corresponding to a highly collapsed flexible tube conveying a critical flow (Reynolds number of 1210) to investigate the three-dimensional flow characteristics, especially in the distal segment. The tube shape, in both axial and transverse planes, is designed from ultra-sound measurements performed on the actual Starling resistor. The opposite walls in the distal tube segment come into contact; the tube then diverges to reach a circular uniform exit segment. The Navier-Stokes equations, associated to the classical boundary conditions, were solved by a finite element method (P1 - P1 bubble element). Where the opposite walls are into contact, the fluid flows through two small drop-shaped outer passages. In the downstream divergent, in- and up(bottom)ward jets are associated to flow separations and to flow characteristics behind an immersed stationary body.