Gradient-consistent enrichment of finite element spaces for the DNS of fluid-particle interaction
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ArticleKAUST Department
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) DivisionApplied Mathematics and Computational Science Program
Extreme Computing Research Center
Date
2019-10-07Online Publication Date
2019-10-07Print Publication Date
2020-01Permanent link to this record
http://hdl.handle.net/10754/659542
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We present gradient-consistent enriched finite element spaces for the simulation of free particles in a fluid. This involves forces being exchanged between the particles and the fluid at the interface. In an earlier work [23] we derived a monolithic scheme which includes the interaction forces into the Navier-Stokes equations by means of a fictitious domain like strategy. Due to an inexact approximation of the interface oscillations of the pressure along the interface were observed. In multiphase flows oscillations and spurious velocities are a common issue. The surface force term yields a jump in the pressure and therefore the oscillations are usually resolved by extending the spaces on cut elements in order to resolve the discontinuity. For the construction of the enriched spaces proposed in this paper we exploit the Petrov-Galerkin formulation of the vertex-centered finite volume method (PG-FVM), as already investigated in [23]. From the perspective of the finite volume scheme we argue that wrong discrete normal directions at the interface are the origin of the oscillations. The new perspective of normal vectors suggests to look at gradients rather than values of the enriching shape functions. The crucial parameter of the enrichment functions therefore is the gradient of the shape functions and especially the one of the test space. The distinguishing feature of our construction therefore is an enrichment that is based on the choice of shape functions with consistent gradients. These derivations finally yield a fitted scheme for the immersed interface. We further propose a strategy ensuring a well-conditioned system independent of the location of the interface. The enriched spaces can be used within any existing finite element discretization for the Navier-Stokes equation. Our numerical tests were conducted using the PG-FVM. We demonstrate that the enriched spaces are able to eliminate the oscillations.Citation
Höllbacher, S., & Wittum, G. (2020). Gradient-consistent enrichment of finite element spaces for the DNS of fluid-particle interaction. Journal of Computational Physics, 401, 109003. doi:10.1016/j.jcp.2019.109003Sponsors
The authors are grateful to D. Logaschenko for the useful discussions and thank A. Vogel and S. Reiter for their support with the implementation in UG4.Publisher
Elsevier BVJournal
Journal of Computational PhysicsAdditional Links
https://linkinghub.elsevier.com/retrieve/pii/S0021999119307089ae974a485f413a2113503eed53cd6c53
10.1016/j.jcp.2019.109003
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Except where otherwise noted, this item's license is described as © 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).