Application of Boundary Element Method to Modelling of Added Mass and Its Effect on Hydrodynamic Forces
Paola Gardano; and Peter Dabnichki

Source CMES: Computer Modeling in Engineering & Sciences, Vol. 15, No. 2, pp. 87-98, 2006
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Keywords Boundary Element Methods; Laplace equations; Added mass; Hydrodynamic forces.
Abstract The work presents a numerical simulation of hydrodynamic forces generated in front crawl swimming. The three dimensional Laplace's equation is used for the analysis of the flow around a moving body in an infinite domain and considers the effect of the added mass and the acceleration on the hydrodynamic forces (Drag and Lift) generated by the interaction between the flow and the body at different geometric configurations of the arm -- variable elbow angle. Boundary Element Method (BEM) was used to obtain the solution of the three dimensional equation numerically. The aim of the work was two-fold: \\ 1) to investigate the effect of the added mass on the scale and trend of the forces and \\ 2) to assess the suitability of BEM for obtaining reliable and accurate solution by validating the results with existing experimental data. \\ BEM showed robust performance as evident from the produced comparison with the experimental data and has clear advantage for this type of problem over computationally expensive computational fluid dynamics approaches.\\ Comparison between directly measured data from experiments on a computer controlled mechanical arm and from numerical simulation using experimentally obtained drag coefficients with the added mass correction showed clearly the significant effect of the added mass and acceleration on the magnitude and profile of hydrodynamic forces. Furthermore the result showed that the added mass effect is the main factor in propulsive force generation that explains some unexpected experimental results by Lauder and Dabnichki (2005) on the profile of the propulsive force throughout the simulated front crawl arm stroke.
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