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Worse accuracy in LES models than in RANS models

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Old   August 30, 2017, 04:56
Default Worse accuracy in LES models than in RANS models
  #1
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Diego Ferrando
Join Date: Mar 2017
Location: Zaragoza
Posts: 19
Rep Power: 9
dferrando is on a distinguished road
Hi Foamers.

I have computed the first case from: http://www.aij.or.jp/jpn/publish/cfdguide/index_e.htm
I have used LES and RANS models to compare the accuracy and computation time from different models but the accuracy on LES models is worse than RANS models.

According to Blocken's paper: http://www.sciencedirect.com/science...45793013000959
The Hit rate(q) in LES models is around 0.9.

My results in OF are the followings:
Spalart Allmaras RANS model q = 0.72
Smagorinsky LES model q = 0.59

I don't understand which is going wrong with LES model.

OF case files:
0/U:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    in
    {
	type            fixedProfile;
     	profile 	csvFile;
     	
	profileCoeffs
	{
		nHeaderLine         0;          // number of header lines
		refColumn           0;          // reference column index
		componentColumns    (1 2 3);    // component column indices
		separator           ",";        // optional (defaults to ",")
		mergeSeparators     no;         // merge multiple separators
		fileName            "0/Uprofile.csv";  // name of csv data file
		outOfBounds         clamp;      // optional out-of-bounds handling
		interpolationScheme linear;     // optional interpolation scheme
	}
	direction        (0 0 1);
	origin 		 0;
    }

    out
    {
        type            pressureInletOutletVelocity;
        value           uniform (0 0 0);
    }

    laterales
    {
        type            noSlip;
    }

    techo
    {
        type            noSlip;
    }

    suelo
    {
        type            noSlip;
    }
   
    bloque
    {
    	type 		noSlip;
    } 
}

// ************************************************************************* //
0/Uprofile.csv:
Code:
0,0,0,0
0.006,2.745,0,0
0.012,2.935,0,0
0.024,3.175,0,0
0.048,3.435,0,0
0.072,3.627,0,0
0.096,3.824,0,0
0.12,4.021,0,0
0.144,4.21,0,0
0.168,4.362,0,0
0.192,4.491,0,0
0.198,4.502,0,0
0.204,4.586,0,0
0.216,4.606,0,0
0.228,4.712,0,0
0.252,4.854,0,0
0.276,4.993,0,0
0.3,5.132,0,0
0.36,5.449,0,0
0.42,5.782,0,0
0.48,6.077,0,0
0.54,6.338,0,0
0.6,6.588,0,0
0.66,6.693,0,0
0.72,6.751,0,0
0.88,6.751,0,0
0/p:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    in
    {
        type            zeroGradient;
    }

    out
    {
        type            totalPressure;
        p0              uniform 0;
        gamma           1.4;
        value           uniform 0;
    }

    laterales
    {
        type            zeroGradient;
    }

    techo
    {
        type            zeroGradient;
    }
		
    suelo
    {
        type            zeroGradient;
    }

    bloque
    {
        type            zeroGradient;
    }
		    
}

// ************************************************************************* //
0/nut:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -1 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    in
    {
        type            calculated;
        value           uniform 0;
    }

    out
    {
        type            calculated;
        value           uniform 0;
    }

    laterales
    {
    	type            nutkWallFunction;
    	value           uniform 0;
    }

    techo
    {
        type            nutkWallFunction;
	value 		uniform 0;
    }

    suelo
    {
        type            nutkWallFunction;
        value           uniform 0;
    }

    bloque
    {
    	type 		nutkWallFunction;
	value 		uniform 0;
    }
}

// ************************************************************************* //
constant/transportProperties:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      transportProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

transportModel  Newtonian;

nu              [0 2 -1 0 0 0 0] 1.5e-05;

// ************************************************************************* //
constant/turbulenceProperties
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      turbulenceProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

simulationType  LES;

LES
{
    LESModel        Smagorinsky;

    turbulence      on;

    printCoeffs     on;

    delta           cubeRootVol;

    cubeRootVolCoeffs
    {
        deltaCoeff      1;
    }

    PrandtlCoeffs
    {
        delta           cubeRootVol;
        cubeRootVolCoeffs
        {
            deltaCoeff      1;
        }

        smoothCoeffs
        {
            delta           cubeRootVol;
            cubeRootVolCoeffs
            {
                deltaCoeff      1;
            }

            maxDeltaRatio   1.1;
        }

        Cdelta          0.158;
    }

    vanDriestCoeffs
    {
        delta           cubeRootVol;
        cubeRootVolCoeffs
        {
            deltaCoeff      1;
        }

        smoothCoeffs
        {
            delta           cubeRootVol;
            cubeRootVolCoeffs
            {
                deltaCoeff      1;
            }

            maxDeltaRatio   1.1;
        }

        Aplus           26;
        Cdelta          0.158;
    }

    smoothCoeffs
    {
        delta           cubeRootVol;
        cubeRootVolCoeffs
        {
            deltaCoeff      1;
        }

        maxDeltaRatio   1.1;
    }
}

// ************************************************************************* //
system/controlDict:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     pisoFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         7;

deltaT          0.0001;

writeControl    timeStep;

writeInterval   5000;

purgeWrite      0;

writeFormat     ascii;

writePrecision  6;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

//adjustTimeStep  yes;

//maxCo           1;

functions
{
  
   fieldAverage1
   {
   	type fieldAverage;
   	libs ( "libfieldFunctionObjects.so" );
   	writeControl writeTime;
        timeStart 2;
	timeEnd   7;


	fields
   	(
   	   U
   	   {
   		mean yes;
   		prime2Mean yes;
   		base time;
   	   }
        );
  }

  probes
  {
   	type            probes;
	libs            ("libsampling.so");
	writeControl    writeTime;
	timeStart 2;
        timeEnd   7;
	
	fields
        (
	  UMean
	  UPrime2Mean
	  U
	);

	probeLocations
	(
	  (-0.06 0 0.01)
	  (-0.06 0 0.04)
	  (-0.06 0 0.08)
	  (-0.06 0 0.12)
	  (-0.06 0 0.14)
	  (-0.06 0 0.16)
	  (-0.06 0 0.17)
	  (-0.06 0 0.19)
	  (-0.06 0 0.22)
	  (-0.06 0 0.28)
	  (-0.04 0 0.17)
	  (-0.04 0 0.19)
	  (-0.04 0 0.22)
	  (-0.04 0 0.28)
	  (-0.02 0 0.17)
	  (-0.02 0 0.19)
	  (-0.02 0 0.22)
	  (-0.02 0 0.28)
	  (0 0 0.17)
	  (0 0 0.19)
	  (0 0 0.22)
	  (0 0 0.28)
	  (0.04 0 0.17)
	  (0.04 0 0.19)
	  (0.04 0 0.22)
	  (0.04 0 0.28)
	  (0.06 0 0.01)
	  (0.06 0 0.04)
	  (0.06 0 0.08)
	  (0.06 0 0.12)
	  (0.06 0 0.14)
	  (0.06 0 0.16)
	  (0.06 0 0.17)
	  (0.06 0 0.19)
	  (0.06 0 0.22)
	  (0.06 0 0.28)
	  (0.1 0 0.01)
	  (0.1 0 0.04)
	  (0.1 0 0.08)
	  (0.1 0 0.12)
	  (0.1 0 0.14)
	  (0.1 0 0.16)
	  (0.1 0 0.17)
	  (0.1 0 0.19)
	  (0.1 0 0.22)
	  (0.1 0 0.28)
	  (0.16 0 0.01)
	  (0.16 0 0.04)
	  (0.16 0 0.08)
	  (0.16 0 0.12)
	  (0.16 0 0.14)
	  (0.16 0 0.16)
	  (0.16 0 0.17)
	  (0.16 0 0.19)
	  (0.16 0 0.22)
	  (0.16 0 0.28)
	  (0.26 0 0.01)
	  (0.26 0 0.04)
	  (0.26 0 0.08)
	  (0.26 0 0.12)
	  (0.26 0 0.14)
	  (0.26 0 0.16)
	  (0.26 0 0.17)
	  (0.26 0 0.19)
	  (0.26 0 0.22)
	  (0.26 0 0.28)
	  (-0.06 0 0.01)
	  (-0.06 -0.02 0.01)
	  (-0.06 -0.04 0.01)
	  (-0.06 -0.05 0.01)
	  (-0.06 -0.07 0.01)
	  (-0.06 -0.09 0.01)
	  (-0.06 -0.12 0.01)
	  (-0.06 -0.16 0.01)
	  (-0.04 -0.05 0.01)
	  (-0.04 -0.07 0.01)
	  (-0.04 -0.09 0.01)
	  (-0.04 -0.12 0.01)
	  (-0.04 -0.16 0.01)
	  (-0.02 -0.05 0.01)
	  (-0.02 -0.07 0.01)
	  (-0.02 -0.09 0.01)
	  (-0.02 -0.12 0.01)
	  (-0.02 -0.16 0.01)
	  (0 -0.05 0.01)
	  (0 -0.07 0.01)
	  (0 -0.09 0.01)
	  (0 -0.12 0.01)
	  (0 -0.16 0.01)
	  (0.04 -0.05 0.01)
	  (0.04 -0.07 0.01)
	  (0.04 -0.09 0.01)
	  (0.04 -0.12 0.01)
	  (0.04 -0.16 0.01)
	  (0.06 0 0.01)
	  (0.06 -0.02 0.01)
	  (0.06 -0.04 0.01)
	  (0.06 -0.05 0.01)
	  (0.06 -0.07 0.01)
	  (0.06 -0.09 0.01)
	  (0.06 -0.12 0.01)
	  (0.06 -0.16 0.01)
	  (0.1 0 0.01)
	  (0.1 -0.02 0.01)
	  (0.1 -0.04 0.01)
	  (0.1 -0.05 0.01)
	  (0.1 -0.07 0.01)
	  (0.1 -0.09 0.01)
	  (0.1 -0.12 0.01)
	  (0.1 -0.16 0.01)
	  (0.16 0 0.01)
	  (0.16 -0.02 0.01)
	  (0.16 -0.04 0.01)
	  (0.16 -0.05 0.01)
	  (0.16 -0.07 0.01)
	  (0.16 -0.09 0.01)
	  (0.16 -0.12 0.01)
	  (0.16 -0.16 0.01)
	  (0.26 0 0.01)
	  (0.26 -0.02 0.01)
	  (0.26 -0.04 0.01)
	  (0.26 -0.05 0.01)
	  (0.26 -0.07 0.01)
	  (0.26 -0.09 0.01)
	  (0.26 -0.12 0.01)
	  (0.26 -0.16 0.01)
	  (-0.06 0 0.1)
	  (-0.06 -0.02 0.1)
	  (-0.06 -0.04 0.1)
	  (-0.06 -0.05 0.1)
	  (-0.06 -0.07 0.1)
	  (-0.06 -0.09 0.1)
	  (-0.06 -0.12 0.1)
	  (-0.06 -0.16 0.1)
	  (-0.04 -0.05 0.1)
	  (-0.04 -0.07 0.1)
	  (-0.04 -0.09 0.1)
	  (-0.04 -0.12 0.1)
	  (-0.04 -0.16 0.1)
	  (-0.02 -0.05 0.1)
	  (-0.02 -0.07 0.1)
	  (-0.02 -0.09 0.1)
	  (-0.02 -0.12 0.1)
	  (-0.02 -0.16 0.1)
	  (0 -0.05 0.1)
	  (0 -0.07 0.1)
	  (0 -0.09 0.1)
	  (0 -0.12 0.1)
	  (0 -0.16 0.1)
	  (0.04 -0.05 0.1)
	  (0.04 -0.07 0.1)
	  (0.04 -0.09 0.1)
	  (0.04 -0.12 0.1)
	  (0.04 -0.16 0.1)
	  (0.06 0 0.1)
	  (0.06 -0.02 0.1)
	  (0.06 -0.04 0.1)
	  (0.06 -0.05 0.1)
	  (0.06 -0.07 0.1)
	  (0.06 -0.09 0.1)
	  (0.06 -0.12 0.1)
	  (0.06 -0.16 0.1)
	  (0.1 0 0.1)
	  (0.1 -0.02 0.1)
	  (0.1 -0.04 0.1)
	  (0.1 -0.05 0.1)
	  (0.1 -0.07 0.1)
	  (0.1 -0.09 0.1)
	  (0.1 -0.12 0.1)
	  (0.1 -0.16 0.1)
	  (0.16 0 0.1)
	  (0.16 -0.02 0.1)
	  (0.16 -0.04 0.1)
	  (0.16 -0.05 0.1)
	  (0.16 -0.07 0.1)
	  (0.16 -0.09 0.1)
	  (0.16 -0.12 0.1)
	  (0.16 -0.16 0.1)
	  (0.26 0 0.1)
	  (0.26 -0.02 0.1)
	  (0.26 -0.04 0.1)
	  (0.26 -0.05 0.1)
	  (0.26 -0.07 0.1)
	  (0.26 -0.09 0.1)
	  (0.26 -0.12 0.1)
	  (0.26 -0.16 0.1)
       );
  }  
}

// ************************************************************************* //
system/fvSchemes:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default    				CrankNicolson 0.9;
}

gradSchemes
{
    default 				Gauss linear;
}

divSchemes
{
    default        			none;
    div(phi,U)      			bounded Gauss linearUpwind grad(U);
    div(phi,p) 	    			Gauss linear;
    div((nuEff*dev2(T(grad(U)))))	Gauss linear;
}

laplacianSchemes
{
    default     			Gauss linear corrected;
}

interpolationSchemes
{
    default     			linear;
}

snGradSchemes
{
    default      			corrected;
}

wallDist
{
    method 				 meshWave;
}

// ************************************************************************* //
system/fvSolution:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    p
    {
        solver          GAMG;
        tolerance       1e-07;
        relTol          0.1;
        smoother        GaussSeidel;
    }

    pFinal
    {
        $p;
        smoother        DICGaussSeidel;
        tolerance       1e-6;
        relTol          0;
    };

    "(U|B)"
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        tolerance       1e-05;
        relTol          0;
    }
}

PISO
{
    nCorrectors     2;
    nNonOrthogonalCorrectors 0;
}

relaxationFactors
{
   fields 
   {
         p               0.3;
   }
   equations
   {
	 U               0.7;
	 ".*"            0.7; 
   }
}


// ************************************************************************* //
Thank you very much and sorry for my poor english, I'm a spanish speaker and I know i must improve a lot.
dferrando is offline   Reply With Quote

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accuracy, hit rate, jia, les, rans

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