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Center for Nonlinear Studies |
Volume of fluid (VOF) simulations track the fractional volumes of each material in a cell. When the interface position is required, it is reconstructed from the volume fraction data. The methods are robust and reliable for two material simulations. However, in cells containing more than two materials, traditional interface reconstruction methods rely on sequential processing of materials to create each material interface in turn. The final interface reconstruction depends on the order in which the materials are processed, a problem known as material order dependency. In some cases, improper material orderings can lead to materials being incorrectly located in a cell breaking up the interface. To fix this, we have developed a new second order accurate, material order independent, multi-material interface reconstruction scheme. The method correctly locates each material within the computational cell using only the volume fraction data, then reconstructs the material interfaces using a weighted Voronoi diagram whose cells match the required volumes. The interface is then smoothed in a material-order independent fashion. The method is completely general working for an arbitrary number of materials on arbitrary convex polygonal grids. It preserves straight lines and all the resulting pure material subcells are convex.