Simulation of bluff-body flows using iterative penalization in a multiresolution particle-mesh vortex method

Henrik Juul Spietz, Mads Mølholm Hejlesen, Jens Honore Walther

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    Abstract

    The ability to predict aerodynamic forces, due to the interaction of a fluid flow with a solid body, is central in many fields of engineering and is necessary to identify error-prone structural designs. In bluff-body flows the aerodynamic forces oscillate due to vortex shedding and variations in the oncoming flow. This may lead to structural instability e.g. when the shedding frequency aligns with the natural frequency of the structure. Fluid structure interaction must especially be considered when designing long span bridges. A three dimensional vortex-in-cell method is applied for the direct numerical simulation of the flow past a bodies of arbitrary shape. Vortex methods use a simple formulation where only the trajectories of discrete vortex particles are simulated. The
    Lagrangian formulation eliminates the CFL type condition that Eulerian methods
    have to satisfy. This allows vortex methods to take significantly larger time steps in
    convection dominated flows with explicit time integration.
    As vorticity is a bounded quantity and the velocity field can be calculated for freespace-
    or periodic boundary conditions, these method allows for a minimized domain
    and hence minimize computational efforts.
    Pure particle-vortex methods have the disadvantage of being highly costly. The
    calculation of particle velocities in particle vortex methods has traditionally been done
    by directly applying the Biot-Savart law yielding an N2
    -body problem. However the
    Poisson equation, that relates the vorticity- to the velocity field, can be solved effi-
    ciently using a mesh-based solver with local refinement in the boundary layer regions.
    We present a higher-order particle-mesh vortex method, where particle velocities
    are calculated by solving the Poisson equation on several uniform meshes using Fast
    Fourier Transforms. This we combine with an iterative penalization method, that
    allows the simulation of external flows past arbitrary geometries in arbitrary motions
    such as bridge decks in forced heave and pitch motion
    Original languageEnglish
    Publication date2016
    Number of pages1
    Publication statusPublished - 2016
    EventECCOMAS Congress 2016: VII European Congress on Computational Methods in Applied Sciences and Engineering - Creta Maris Conference Center, Hersonissos, Greece
    Duration: 5 Jun 201610 Jun 2016
    https://www.eccomas2016.org/

    Conference

    ConferenceECCOMAS Congress 2016
    LocationCreta Maris Conference Center
    Country/TerritoryGreece
    CityHersonissos
    Period05/06/201610/06/2016
    Internet address

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