A New Volume-Of-Fluid Method in Openfoam

Johan Rønby Pedersen, Bjarke Eltard Larsen, Henrik Bredmose, Hrvoje Jasak

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    Abstract

    To realise the full potential of Computational Fluid Dynamics (CFD) within ma-rine science and engineering, there is a need for continuous maturing as well as verificationand validation of the numerical methods used for free surface and interfacial ows. One of thedistinguishing features here is the existence of a water surface undergoing large deformationsand topological changes during transient simulations e.g. of a breaking wave hitting an off-shore structure. To date, the most successful method for advecting the water surface in marineapplications is the Volume-of-Fluid (VOF) method. While VOF methods have become quiteadvanced and accurate on structured meshes, there is still room for improvement when it comesto unstructured meshes of the type needed to simulate ows in and around complex geometricstructures. We have recently developed a new geometric VOF algorithm called isoAdvector forgeneral meshes and implemented it in the OpenFOAM interfacial ow solver called interFoam.We have previously shown the advantages of isoAdvector for simple pure advection test caseson various mesh types. Here we test the effect of replacing the existing interface advectionmethod in interFoam, based on MULES limited interface compression, with the new isoAd-vector method. Our test case is a steady 2D stream function wave propagating in a periodicdomain. Based on a series of simulations with different numerical settings, we conclude that theintroduction of isoAdvector has a significant effect on wave propagation with interFoam. Thereare several criteria of success: Preservation of water volume, of interface sharpness and shape,of crest kinematics and celerity, not to mention computational effciency. We demonstrate howisoAdvector can improve on many of these parameters, but also that the success depends on thesolver setup. Thus, we cautiously conclude that isoAdvector is a viable alternative to MULESwhen set up correctly, especially when interface sharpness, interface smoothness and calcula-tion times are important. There is, however, still potential for improvement in the coupling ofisoAdvector with interFoam's PISO based pressure-velocity solution algorithm.
    Original languageEnglish
    Title of host publicationMARINE 2017 Computational Methods in Marine Engineering VII
    EditorsMichel Visonneau, Patrick Queutey, David Le Touzé
    Place of PublicationNantes
    PublisherInternational Center for Numerical Methods in Engineering
    Publication date2017
    Pages266-278
    ISBN (Electronic)978-84-946909-8-3
    Publication statusPublished - 2017
    Event7th International Conference on Computational Methods in Marine Engineering - Nantes, France
    Duration: 15 May 201717 May 2017
    Conference number: 7

    Conference

    Conference7th International Conference on Computational Methods in Marine Engineering
    Number7
    Country/TerritoryFrance
    CityNantes
    Period15/05/201717/05/2017

    Keywords

    • CFD
    • Marine Engineering
    • Interfacial Flows
    • IsoAdvector
    • VOF Methods
    • Surface Gravity Waves

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