[noodleluvmay]

Hello,

As I am viewing the relaxationZoneLayout to check on the relaxation setup, I have realised the zone seems to be shifted slightly in my refined region.

I meshed the domain in 3 parts, aiming to have finer mesh close to the water surface level, however, the middle region seems to have been shifted 1 cell length in the +X direction as shown in the attached photo. I am not sure why this is the case.

There have also been some numerical instabilities, where floating point exception error, or extremely small time steps would occur after a few sections into the simulation, with diverging velocity towards the outlet relaxation zone. I am unsure if this might be the cause.




Please find my definition of the relaxation zone below:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  1.5                                   |
|   \\  /    A nd           | Web:      http://www.OpenFOAM.org               |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      environmentalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

seaLevel	0.00;

// A list of the relaxation zones in the simulation. The parameters are given
// in <name>Coeffs below.
relaxationNames (inlet outlet);

initializationName outlet;

inletCoeffs
{
    // Wave type to be used at boundary "inlet" and in relaxation zone "inlet"
    waveType	stokesSecond;
    
    // Ramp time of 2 s
    Tsoft       0.513;

    // Water depth at the boundary and in the relaxation zone
    depth       0.4;

    // Wave period
    period      0.513;

    // Phase shift in the wave
    phi         0.000000;

    // Wave number vector, k. 
    direction  (1.0 0.0 0.0);
	// waveNumber (0.3314 0 0);

    // Wave height
    height      0.00395;
	
	// stokesSecond specific
	debug		off;
    
    // Specifications on the relaxation zone shape and relaxation scheme
    relaxationZone
    {
        relaxationScheme Spatial;
        relaxationShape  Rectangular;
        beachType        Empty;
    
        relaxType   INLET;
        startX      (-2.46 -0.001 0.0);
        endX        (-0.41 0.001 0.0);
        orientation      (1.0 0.0 0.0);
    }
};

outletCoeffs
{
    waveType    potentialCurrent;
    U           (0 0 0);
    Tsoft       0.513;

    relaxationZone
    {
        relaxationScheme Spatial;
        relaxationShape  Rectangular;
        beachType        Empty;    

        relaxType   OUTLET;
        startX      (0.82 -0.001  0.0);
        endX        (2.46 0.001  0.0);
        orientation      (1.0 0.0 0.0);
    }
};



// ************************************************************************* //

I would really appreciate it if anyone would have any idea on why this is happening, and if it would impact my results or not.

Thank you!