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Inlet velocity profile

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  • #6253

    I am simulating turbulent single-phase flow in a horizontal pipe using the D3Q27 descriptor, SmagorinskyBGKdynamics, no-slip condition at the wall and I use CirclePoiseuille3D velocity profile at the inlet.
    Are there other options for inlet velocity such as constant velocity etc?

    Following is my code for boundary values:

    PolynomialStartScale<T,int> StartScale( iTmaxStart, converter.getCharLatticeVelocity() );

    // Creates and sets the Poiseuille inflow profile using functors
    // int iTvec[1] = {iT};
    //T frac[1] = {};
    // StartScale( frac,iTvec );
    //std::vector<T> maxVelocity( 3,0 );
    //maxVelocity[0] = 2.25*frac[0]*converter.getCharLatticeVelocity();
    int iTvec[1]= {iT};
    T maxVelocity[1]= {T()};
    StartScale( maxVelocity,iTvec );
    CirclePoiseuille3D<T> poiseuilleU( superGeometry,3,maxVelocity [0] );
    sLattice.defineU( superGeometry,3,poiseuilleU );

    Thank you


    I check the velocity profile at the end of the pipe.
    I see the profile is exactly the same at inlet (Poiseuille flow profile) even though I Reynolds number is 10005 and I use SmagorinskyBGKdynamics.

    Please can someone explain to me what is wrong with my code, am I missing something?

    Thank you in advance.


    How did you determine that your simulation models Re = 10005? At which resolution and for what timespan are you simulating? Did you check the entire Paraview output? Did you base your setup on some existing example of ours?


    1) I calculated using: Re = (inletvelocity*pipediameter)/(kinematicviscosity); (inletvelocity=0.9423m/s, Pipediameter=0.04m; kinematicviscosity=0.0044 (kg/m-s)/1168 (kg/m3))
    I also see the same Reynolds number in the UnitConversion Information Parameters output.

    2) I use N=50 and M=50

    3) Timespan = 10 second

    4) I use .pvd file in paraview and put a vertical line at the outlet and plot velocity vs diameter of pipe

    5) I just modify your the existing examples.


    Hi Adrian,
    One more thing I need to mention.
    If I keep everything the same and just change the descriptor to either D3Q19 or D3Q27, the results are different.
    At the outlet
    D3Q27 gives me the same velocity profile as inlet (Poiseuille)
    D3Q19 give me fluctuation at the outlet no particular pattern

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