Wall shear stress in a laminar flow through a collapsed tube with wall contact

The present work aims at studying mainly the wall shear stress of a laminar steady flow of an incompressible Newtonian fluid which is conveyed through a collapsed tube with a straight centreline. This tube is composed of a tapered segment, a contact segment where the opposite walls touch and a reopening segment. The tube geometry and steady flow characteristics are obtained from measurements in a collapsed tube. The Navier-Stokes equations associated with the classical boundary conditions are solved using the finite element method. The tridimensional flow results from the tube configuration. In particular, the flow consists of two side-jets due to two tear-drop shaped outer passages in the downstream contact segment associated with reversed flow. In order to compute both the stream-wise and cross-wise components of the shear stress on the wall, a local basis is defined in each wall node. Downstream of the contact segment, flow is separated in two jets which are studied though the help of the velocity field and the wall shear stress.