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Description:
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The average or continuum level behavior of suspensions is investigated by modeling of discrete particles and time -averaging their behavior . Because of the long -range behavior of the Stokes equations , this system has to account for multi -particle interactions that are not pair -wise additive . While there are several methods to account for such interactions , the boundary element method converges to an exact representation of the multi -particle dynamics as the mesh density increases . What has not been determined is how good these simulations have to be in order to capture the relevant physics for the continuum level behavior .
To adequately benchmark the BEM model , a transient 3 -D problem with an analytical solution is necessary . Such a problem for two smooth spheres has been given by DaCunha and Hinch in 1996 . Using numerical approximations to this solution , the effect of time integration schemes on this system was investigated . Because most modem codes use adjustable time -step algorithms that limit the local time integration error in an attempt to control the global integration error , the dependence of the global error on the local error was determined . While this analysis is valid for two spheres and does raise possible concerns about the multi -particle dynamics , it does not give quantitative number for multi -particle BEM simulations . Possible future work will be outlined that extends the analysis presented in this thesis work from two -particle systems to many -particle systems that are more representative of real suspensions . The requirements and a suggested method will be discussed . |