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CivilComp Proceedings
ISSN 17593433 CCP: 94
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON ENGINEERING COMPUTATIONAL TECHNOLOGY Edited by: B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru and M.L. Romero
Paper 154
Numerical Analysis of the FluidStructure Interaction in a Membrane Pump J. Bols, L. Taelman, J. Degroote, S. Annerel and J. Vierendeels
Department of Flow, Heat and Combustion Mechanics, Ghent University, Belgium J. Bols, L. Taelman, J. Degroote, S. Annerel, J. Vierendeels, "Numerical Analysis of the FluidStructure Interaction in a Membrane Pump", in B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru, M.L. Romero, (Editors), "Proceedings of the Seventh International Conference on Engineering Computational Technology", CivilComp Press, Stirlingshire, UK, Paper 154, 2010. doi:10.4203/ccp.94.154
Keywords: membrane pump, pumping of biological fluids, fluidstructure interaction, partitioned solution, interface quasiNewton, mesh motion technique.
Summary
In this research, the fluidstructure interaction in a recently developed membrane pump is analysed.
The rigid casing of this pump consists of a hollow circular cylinder with a height that is
smaller than its radius. This casing encloses a flexible, circular membrane with a hole at its center. An electromagnet applies an oscillating motion parallel to the axis of the cylinder at the outer edge of the membrane. As a result, waves travel from the outer edge of the membrane towards its center. Hence, the fluid on both sides of the membrane is pumped from the side of the cylinder to the outlet at the center.
These membrane pumps are ideally suited for biomedical applications and particleladen flows.
The numerical simulation of such a multiphysics problem is challenging. In this research, the governing equations for the laminar flow of the incompressible fluid and the equations for the deformation of the membrane are solved with two separate codes, which are coupled with the interface quasiNewton technique with an approximation for the inverse of the Jacobian from a leastsquares model (IQNILS) [1]. This coupling algorithm requires fewer coupling iterations per time step than dynamic relaxation techniques. Apart from the interaction, another difficulty in the numerical simulation of these pumps is the strongly deforming fluid domain, due to the large deformation of the structure. To obtain an accurate calculation of the stress on the fluidstructure interface, the flow equations are solved in the arbitrary LagrangianEulerian formulation on a deforming mesh. An innovative combination of mesh motion corresponding to the solution of Laplace equations, mesh smoothing and remeshing is used to maintain a highquality mesh throughout the simulation. A detailed analysis of the flow field, the deformation of the structure and the stress in the membrane is presented. An energetic analysis of the pump is performed. The mean mass flow rate supplied by the pump is 95.6g/s. The deflection of a point at the membrane's center is approximately a factor of three higher than the excitation amplitude. This large displacement restricts the excitation amplitude. The relatively large distance between the membrane and the casing of the pump entails a large backflow which consequently leads to a relatively low efficiency of 30.3%. References
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