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lift and drag calculation in LBM

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› Forums › Lattice Boltzmann Methods › General Topics › lift and drag calculation in LBM

Viewing 4 posts - 1 through 4 (of 4 total)
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  • August 6, 2025 at 5:50 pm #10635
    garcfd
    Participant

    How do people usually calculate lift or drag in LBM code?

    1. integrate pressure over the body surface?

    2. momentum exchange method at the boundary wall?

    3. wake-traverse method to integrate u(Uinf-u) at downstream plane?

    I have tried a few different methods and they are all highly dubious, giving variable numbers.
    I would love to know if there are reliable / accurate methods for calculating the drag in LBM.
    Thankyou.

    August 6, 2025 at 9:38 pm #10636
    mathias
    Keymaster

    Option 2 is what is usually been doen and what OpenLB uses as well!

    August 6, 2025 at 11:11 pm #10637
    garcfd
    Participant

    Thanks – can you point me to the paper (or code) which describes how the momentum exchange method was implemented (please)?

    August 7, 2025 at 2:13 pm #10638
    garcfd
    Participant

    I just spotted a couple of clues in the source code:

    MOMENTUM_EXCHANGE_FORCE_H
    //Momentum Exchange Wen2014
    return (f1*(c-pVel) + f2*(c+pVel));

    //Momentum Exchange Ladd1994
    return ((f1 + f2)*c);

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