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Freesurface piercing foil numerical wiggles in gamma isosurface

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Old   April 7, 2007, 10:15
Default Hi, I am running rasInterFo
  #1
egp
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Eric Paterson
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Hi,

I am running rasInterFoam for a free-surface piercing NACA 0024 hydrofoil at Fr = 0.55. Overall, the solution looks quite good with nice resolution of the bow wave, the wave profile, and the spilling breaking wave.

So, what's the issue? I've run both coarse (~0.3M cells) and fine (~2M cells) hex meshes, and have some non-physical small amplitude waves in the gamma field which are seen on the gamma=0.5 iso-surface (i.e., the free surface).

Anyone have suggestions on fvSchemes settings to eliminate this problem? I am using standard rasInterFoam settings,

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

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
div(rho*phi,U) Gauss upwind;
div(phi,gamma) Gauss limitedLinear01 1;
div(phirb,gamma) Gauss limitedLinear01 1;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phi,nuTilda) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(HbyA) linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
pd;
pcorr;
gamma;
}


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

To get an idea of what I am seeing, I've put a couple of animations (naca0024...) for download at:

http://homepage.mac.com/egpaterson/FileSharing2.html

Thanks,

Eric
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Old   April 8, 2007, 18:18
Default Try: div(phi,gamma) Gaus
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Hrvoje Jasak
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Try:


div(phi,gamma) Gauss Gamma01 1;
div(phirb,gamma) Gauss Gamma01 1;


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Old   April 9, 2007, 19:02
Default Hrv, I tried the Gamma01 sc
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Eric Paterson
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Hrv,

I tried the Gamma01 scheme, although I did restart from the exisiting solution. However, it had no noticable impact.

We'll have to do some more digging to understand this better.

Eric
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Old   April 11, 2007, 03:13
Default Hi Eric I have had the same
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Hi Eric

I have had the same problems using interFoam. The only way I have found to eliminate the overshoots is to use

div(rho*phi,U) Gauss upwind;
div(phi,gamma) Gauss upwind;


Regards

/Joakim
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Old   April 12, 2007, 11:02
Default Hi Joakim, Thanks, as you c
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Eric Paterson
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Hi Joakim,

Thanks, as you can see from the image which compares upwind vs. limitedLinear01 on gamma , the upwind scheme took care of the problem as would be expected with a first order scheme. However, it also smoothed the diverging wave in the wake. I'm going to test out the other TVD schemes.

Eric
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Old   April 12, 2007, 11:17
Default Here's the 3D view http://www.
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Here's the 3D view .

Eric
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Old   May 1, 2007, 16:26
Default Hello, I am continuing to w
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Hello,

I am continuing to work on this case. I would like to get a 2nd-order scheme working without the non-physical waves that were smoothed out by upwind.

Currently I am working with rasInterFoam, FR=0.55, coarse (~246,000 cell) grid. This is the same case Eric posted about above, all is the same except my fvSchemes dict which is below:


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

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
div(rho*phi,U) Gauss MUSCL;
div(phi,gamma) Gauss MUSCL;
div(phirb,gamma) Gauss MUSCL;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phi,nuTilda) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(HbyA) MUSCL;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
pd;
pcorr;
gamma;
}


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

Has anyone had any experience/problems implementing MUSCL?

I've run the following to attempt to get the solution started:
(1) water/air density ratio: 1000:100
CFL=0.1
ran OK for 75 time steps

(2) 1000:10
CFL=0.1
Did not work in that pcorr iterations were >5000 and/or deltaT was less than 1e-33 or CFL greater than 1.0

(3) changed to CFL=0.05, 0.04, 0.03
crashed in a similar manner

(4) changed the water/air density ratio to 1000:100 again and CFL=0.1: Runs OK!

(5) changed density ratio to 1000:50
CFL=0.1
runs OK

(6) changed density ratio to 1000:1
CFL=0.1, 0.05, 0.025, 0.0125, 0.00625
crashed as above

My next thought is to try ratio of 1000:10.

Any thoughts/comments/suggestions would be greatly appreciated.

Thank you,
Ryan Carley
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Old   May 2, 2007, 08:49
Default Have you tried OF1.4 with the
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Have you tried OF1.4 with the MULES scheme for gamma yet?

You categorically cannot run Gamma with a scheme that is not strictly bounded between 0 and 1, e.g. MULES or gamma01
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Old   May 2, 2007, 08:59
Default Belay that, just check the OF1
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Belay that, just check the OF1.4 tutorials for what schemes to use on gamma.
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