[ihu945]

Hello, foamers.
I am trying to do a simulation Flow around a circular cylinder near a plane wall.
However, because of weirdly high courant number by too high velocity, I cannot do simulation.

convertToMeters 1;

vertices
(
    (-10 -1.5 0)            
    ( 10 -1.5 0)            
    (30 -1.5 0)        
    (-1.0607 -1.0607 0)
    (1.0607 -1.0607 0)    
    (-0.3536 -0.3536 0)        
    ( 0.3536 -0.3536 0)        
    (-0.3536  0.3536 0)        
    ( 0.3536  0.3536 0)
    (-1.0607 1.0607 0)
    (1.0607 1.0607 0)
    (-10 15 0)            
    ( 10 15 0)            
    (30 15 0)            
    
    (-10 -1.5 1)            
    ( 10 -1.5 1)            
    (30 -1.5 1)        
    (-1.0607 -1.0607 1)
    (1.0607 -1.0607 1)    
    (-0.3536 -0.3536 1)        
    ( 0.3536 -0.3536 1)        
    (-0.3536  0.3536 1)        
    ( 0.3536  0.3536 1)
    (-1.0607 1.0607 1)
    (1.0607 1.0607 1)
    (-10 15 1)            
    ( 10 15 1)            
    (30 15 1)    
    
);

blocks
(
    hex (0 3 9 11 14 17 23 25) (10 10 1) simpleGrading (1 1 1)
    hex (1 4 3 0 15 18 17 14) (10 10 1) simpleGrading (1 1 1)
    hex (4 1 12 10 18 15 26 24) (10 10 1) simpleGrading (1 1 1)
    hex (10 12 11 9 24 26 25 23) (10 10 1) simpleGrading (1 1 1)
    hex (3 5 7 9 17 19 21 23) (10 10 1) simpleGrading (1 1 1)
    hex (4 6 5 3 18 20 19 17) (10 10 1) simpleGrading (1 1 1)
    hex (6 4 10 8 20 18 24 22) (10 10 1) simpleGrading (1 1 1)
    hex (8 10 9 7 22 24 23 21) (10 10 1) simpleGrading (1 1 1)
    hex (1 2 13 12 15 16 27 26) (10 10 1) simpleGrading (1 1 1)
);

edges
(
   arc 5 7 (-0.5 0 0)
   arc 19 21 (-0.5 0 1)
   arc 6 8 (0.5 0 0)
   arc 20 22 (0.5 0 1)
   arc 7 8 (0 0.5 0)
   arc 21 22 (0 0.5 1)
   arc 5 6 (0 -0.5 0)
   arc 19 20(0 -0.5 1)
   arc 3 9 (-1.5 0 0)
   arc 17 23 (-1.5 0 1)
   arc 4 10 (1.5 0 0)
   arc 18 24 (1.5 0 1)
   arc 9 10 (0 1.5 0)
   arc 23 24 (0 1.5 1)
   arc 3 4 (0 -1.5 0)
   arc 17 18 (0 -1.5 1)
);

boundary
(
    inlet
    {
        type wall;
        faces
        (
            (25 11 0 14)
        );
    }
    
    outlet
    {
        type wall;
        faces
        (
            (13 27 16 2)
        );
    }
    
    top
    {
        type wall;
        faces
        (
            (12 11 25 26)
        (13 12 26 27)
        );
    }
    
    bottom
    {
        type wall;
        faces
        (
            (0 1 14 15)
        (1 2 15 16)
        );
    }
    
    cylinder
    {
        type wall;
        faces
        (
            (7 8 21 22)
            (22 8 6 20)
        (6 5 19 20)
        (5 7 21 19)        
    );
    }
    
    sides
    {
        type empty;
        faces
        (
            (11 12 10 9)
        (0 11 9 3)
        (0 3 4 1)
        (4 10 12 1)
        (9 10 8 7)
        (3 9 7 5)
        (3 5 6 4)
        (6 8 10 4)
        (12 13 2 1)
        
        (25 23 24 26)
        (14 17 23 25)
        (14 15 18 17)
        (18 15 26 24)
        (23 21 22 24)
        (17 19 21 23)
        (17 18 20 19)
        (20 18 24 22)
        (26 15 16 27)
        );
    }
);

mergePatchPairs
(
);

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 (1 0 0);
    }

    outlet
    {
        type            zeroGradient;
    }
    
    top
    {
    type        zeroGradient;
    }

    bottom
    {
    type        fixedValue;
    value        uniform (0 0 0);
    
    }
    
    cylinder
    {
    type        fixedValue;
    value        uniform (0 0 0);
    }
    
    sides
    {
        type            empty;
    }
}

These are my blockMeshDict and initial condition for velocity.
And pictures below are from paraview.
when t = 0,
posting1.jpg
When t = 0.003
posting2.jpg
And bottom part of second picture,
posting3.jpg
Like this, velocity of bottom becomes very high, and I have no idea that it is right or something is wrong.
Please, help me.
Thank you