BUBBLE VELOCITY ENRICHMENT FOR EMBEDDED INTERFACES IN MULTI-FLUID FLOWS: A CRIME THAT DOES NOT PAY

BUSCAGLIA GUSTAVO; AUSAS ROBERTO; NIGRO NORBERTO; IDELSOHN, SERGIO

Mendoza

Congreso; ENIEF 2013; 2013

AMCA

We discuss ongoing work on the addition of a statically condensable bubble enrichment tocapture kinks (surfaces where the function is continuous but its gradient exhibits a jump) in the velocityfield at immersed interfaces not conforming with the element boundaries. Such kinks are frequent inmulti-fluid flows because they arise whenever there are viscosity jumps or thermo-capillary effects. Theenrichment is applied only at those elements of the finite element mesh cut by the interface, which is parameterizedin this case with a level set function. The bubble function used in this work was introducedelsewhere (see Codina and Coppola-Owen, Int. J. Num. Meth. in Fluids 2005; 49:1287-1304) to capturediscontinuities in the pressure gradient for two-phase flows, which arise because of density discontinuitiesunder gravity. Its applicability as enrichment of the velocity field is not obvious due to a consistencyerror it creates in the variational formulation (the enrichment velocity fields are not in H1(), since theyare discontinuous at some inter-element boundaries). In this work we assess the accuracy, robustnessand limitations of this new enrichment in some problems involving interfaces. In its current form, thenon-conformity of the bubbles introduces an unphysical numerical error which is of the same order asthe interpolation error the bubbles are there to alleviate. Notice that these same bubble functions, whenused for the pressure, do not lead to consistency error because they do belong to L2().Mecánica Computacional Vol XXXII, págs. 1785-1797 (artículo completo)Carlos G. García Garino, Aníbal E. Mirasso, Mario A. Storti, Miguel E. Tornello (Eds.)Mendoza, Argentina, 19-22 Noviembre 2013Copyright ©