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Item type:Publication, Access status: without files , Hybrid MPI/OpenMP parallelization of an Euler-Lagrange approach to cavitation modellingAn Euler-Lagrange approach is developed for numerical simulations of cavitating flows. Within this approach the Navier-Stokes equations are solved for the Eulerian liquid/vapor-mixture. Supplementary equations for the bubble size and motion are solved for each of the bubbles/nuclei, composing a discrete vapor phase. Such an approach is computationally demanding when computational grids with several Mio cells and many ten thousand bubbles are considered. The paper reports the development and verification of an efficient hybrid MPI/OpenMP algorithm for coupled Euler-Lagrange simulations. The proposed algorithm facilitates cavitation predictions for challenging industrial applications, such as cavitating marine propellers, in a reasonable amount of wall-clock time.Publicationtype: Journal Article221 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Advanced Lagrangian approaches to cavitation modelling in marine applications(Springer, 2011); ; ; ; © 2013 Springer Science+Business Media Dordrecht. The paper scrutinizes different approaches to cavitation modelling in the framework of volume of fluid based marine engineering Navier-Stokes simulations. Traditional Eulerian cavitation models compute the vapor content based on computationally efficient, semi-empirical mass-transfer models for cavitation. In conjunction with Lagrangian cavitation models, separate equations for the bubble size and momentum are solved for each individual bubble/nuclei of a dispersed vapor phase, and a subsequent mapping procedure provides the vapor-volume fraction of the Eulerian mixture. The paper aims to advocate the benefits of a combined approach, which reduces the computational effort of the Lagrangian approach whilst maintaining its enhanced predictive realm in critical flow regimes. Validation examples refer to 2D hydrofoils and outline the strong parameter dependency for the Eulerian cavitation models as well as its insensitivity to water-quality aspects. On the contrary, Lagrangian cavitation models return an improved accuracy and capture the influence of water quality. Results of an open-water propeller flow investigation confirm these findings and display a fair predictive agreement in conjunction with a combined modelling approach which allows to perform accurate cavitation predictions at reasonable cost.Publicationtype: Conference Paper138 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Euler-Euler and Euler-Lagrange approaches to cavitation modelling in marine applications(International Center for Numerical Methods in Engineering (CIMNE), 2011); ; ; ; Two different approaches to cavitation modelling are investigated in the paper. With the Euler-Euler approach vapour-volume fraction is computed based on a volume of fluid method in combination with a simple mass-transfer model for cavitation. Using an Euler-Lagrange approach, separate equations for bubble size and motion are solved for each of the bubbles/nuclei. Computed bubbles are subsequently mapped to an Eulerian field to obtain vapour-volume fraction of the Eulerian mixture field. Numerical results of a 2D hydrofoil and a propeller flow demonstrate strong parameter dependency for the Euler-Euler approach. Providing the correct (measured) initial bubble distribution, Euler-Lagrange techniques display a fair amount of predictive accuracy as demonstrated for a 2D hydrofoil.Publicationtype: Conference Paper49