[MNoCeZ]

Hello together,


i made a simulation of two boxes with same size . Both boxes are connect through the cyclicPeriodicAMI boundary condition. Both boxes have cyclicPeriodic walls in y and z direction. In a next step i adapted the linearMotion function:

Foam::septernion
Foam::solidBodyMotionFunctions::linearPeriodicMotion::transformation() const
{
    scalar t = time_.value();
    
    scalar linear_displacement =0.0;
    
    if (pitchSpeed_ > 0.0)
    {
        linear_displacement = fmod(pitchSpeed_*t,pitch_);
    }

    if (pitchSpeed_ < 0.0)
    {
        linear_displacement = fmod(pitchSpeed_*t,-pitch_);
    }     
    
    //const vector velocity = (0 pitchSpeed_ 0);
    // Translation of centre of gravity with constant velocity
    vector displacement;
    
    displacement.x()=0.0;
    displacement.y()=linear_displacement;
    displacement.z()=0.0;
    
    quaternion R(1);
    septernion TR(septernion(-displacement)*R);

    DebugInFunction << "Time = " << t << " transformation: " << TR << endl;

    return TR;
}


bool Foam::solidBodyMotionFunctions::linearPeriodicMotion::read
(
    const dictionary& SBMFCoeffs
)
{
    solidBodyMotionFunction::read(SBMFCoeffs);

    //SBMFCoeffs_.lookup("velocity") >> velocity_;
    
    
    SBMFCoeffs_.lookup("pitchSpeed") >> pitchSpeed_;
    SBMFCoeffs_.lookup("pitch") >> pitch_;
    

    return true;
}

the idea is to move the second box with a constant speed pitchSpeed in y direction until the covered distance corresponds to the box size in y direction. The position of the moving box should then be reset and the process repeated. The problem is that after resetting the box the time step becomes very small and unphysical values occur. One way to solve this problem would be to restart the simulation after the box has been resetted. However, this is not very effective. Does anyone have an idea how I could solve the problem more elegantly? I am using v1612+.

Best regards


Mark