Week 12 - Validation studies of Symmetry BC vs Wedge BC in OpenFOAM vs Analytical H.P equation

In this challange a comparison was made by using the 2 boundary conditions

1.Symmetry

2.Wedge

Symmetry

In the Symmetry boundary condition the front and back side of the sector , is given the symmetry BC , and by varying the angle of the sector we compare wth the analytical and with each other

The blockMeshDict file for the symmetry boundary condition is created accordingly

for 10 deg angle

 FoamFile
 {
 version           2.0;
 format           ascii;
 class           dictionary;
 object           blockMeshDict;
 }
 convertToMeters   1;
 
 
vertices 
(
(0      0             0)
(2.05      0             0)
(0  0.005   4.3744e-04)
(2.05  0.005  4.3744e-04)
(2.05  0.005  -4.3744e-04)
(0  0.005  -4.3744e-04)
);
 
blocks
(
	hex (0 1 1 0 2 3 4 5) (100  1 15) simpleGrading (1 1 1 )
);
 
edges ( 
        );
 
 boundary 
(
 
inlet
{
        type patch;
        faces (
        (0 0 2 5)
        );
}
 
outlet
{
        type patch;
        faces (
        (1 1 4 3)
         );
}
 
top
{
        type wall;
        faces (
        (2 3 4 5)
         );
}
 
front
{
        type symmetry;
        faces (
        (0 1 3 2)
        );
}
 
Back
{
        type symmetry;
        faces (
        (0 1 4 5)
         );
}
 
Axis
{
        type empty;
        faces (
         (0 1 1 0)
         );
}
);
 
mergePatchPairs (
);

the file remains same for 25 deg and 45 deg angle except for the z axis points on the vertices 2,3,4 and 5

The 0/U file

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  7
     \\/     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
{
    inlet
    {
        type            fixedValue;
        value           uniform (0.21084 0 0);
    }

    top
    {
        type                 noSlip;
       
    }

    Back
    {
        type            symmetry;
    }

    front
    {
        type            symmetry;
    }
   
   outlet 
   {
       type         zeroGradient;
   } 

   Axis
   
   {
     type             empty;
   }


}



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

0/P file

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  7
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 1;

boundaryField
{

    inlet
     {

      type       zeroGradient;

     }
    
    outlet
      {

      type          fixedValue;
      value         uniform 0.86114;
     
      } 

    top
    {
        type            zeroGradient;
    }

    front
    {
        type            symmetry;
    }

   Back 

   {
   
    type               symmetry;
    

  }

    Axis
  
 { 
     type               empty;

   }
    
}

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

The changes in the vertices for 25 deg in blockMeshDIct are

vertices 
(
(0      0             0)
(2.05      0             0)
(0  0.005   0.0011085)
(2.05  0.005  0.0011085)
(2.05  0.005  -0.0011085)
(0  0.005  -0.0011085)
);

The changes in the vertices for 45 deg in blockMeshDIct are

vertices 
(
(0      0             0)
(2.05      0             0)
(0  0.005   0.0020711)
(2.05  0.005  0.0020711)
(2.05  0.005  -0.0020711)
(0  0.005  -0.0020711)
);

by using the icofoam solver and time step as 0.0001 , every case is solved for 5 sec

The following results were obtained

The variation of the pressure from the inlet to outlet , at the fully developed flow region , the pressure drop obtained was 0.083908

The maximum velocity obtained was 0.41787 m/s

The maximum velocity obtained at the hydrostatic entry length was 0.41339 m/s

25 degree

the maximum velocity at the fully developed flow is 0.417878

The variation of the pressure from inlet to outlet 25 symmetry delp = 0.16648

45 Deg Symmetry BC

max velocity at hydrostatic entry length =0.41339 m/s

max velocity at hydrostatic entry length =0.41788m/s

Pressure drop in along the length is 0.16648

wedge

for a wedge BC the blockMeshDict File , is changed at the front and back as type wedge

 Back
    {
        type            wedge;
    }

    front
    {
        type            wedge;
    }

ther remaining file for each angle remains the same as symmetry BC

for 10 degree

the max velocity at the hydrostatic entry length is 0.41338 m/s

Max velocity at the fully developed flow =0.41901 m/s

The pressure drop across the length is 0.16648

25 degree

max velocity=0.41338 m/s

maximum velocity =0.417878 m/s

pressure drop = 0.16648

45 deg Wedge BC

Maximum velocity is 0.41338 m/s

@ 45 wedge Vmax hel =0.41339 m/s

@ 45 wedge Vmax fdf =0.41788 m/s

@ 45 wedge BC delp = 0.19865

@ 45 wedge tau = 0.083912

wedge_max =

0.41901 0.41788 0.41788