A numerical solution to the unsteady blood flow in the neighbourhood of an overlapping constriction is obtained under laminar flow conditions. Blood is modelled as a viscous, incompressible and of Newtonian type fluid. A finite-difference staggered grid has been used to solve the unsteady incompressible Navier-Stokes equations in cylindrical polar co-ordinates under the axi-symmetric conditions. A co-ordinate transformation has been employed to map the constricted tube into a straight tube. The effect of flow characteristics in this type of constriction and its consequences in arterial diseases are investigated. Flow features such as velocity, pressure and wall shear stress distributions are presented graphically. The secondary separation has been noted in the downstream of the overlapping constriction when the Reynolds number of the flow is about 205.
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The numerical solution to the problem of viscous incompressible flow of a Newtonian fluid in a locally expanded channel has been obtained for low and moderate high Reynolds numbers under laminar conditions. The well-known finite difference scheme in a staggered grid due to Harlow and Welch (1965) is used to discretize the equations of fluid flow. The present algorithm is of two-stages. In the first stage, Poisson equation for pressure has been solved iteratively and then pressure velocity corrections are made in the second stage. The flow characteristics such as the wall shear stress, velocity distribution and pressure distribution are then calculated. The results are presented graphically and discussed.
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