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interFoam: type flowRateInletVelocity does not return the expected results

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Old   March 29, 2022, 00:33
Default interFoam: type flowRateInletVelocity does not return the expected results
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William
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Hi everyone, to validate the use of flowRateInletVelocity type, I have a cubic container with a side of 100m, which receives water at 500m3/s, considering the volume of the container (100^3=1000000m3), it must be filled in 2000 seconds, my U and blockMeshDict dictionaries are as follows.


U

Code:
FoamFile
{
    version     2.0;
    format      ascii;
    arch        "LSB;label=32;scalar=64";
    class       volVectorField;
    location    "0";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (1 0 0);

boundaryField
{
    inlet
    {
        type            flowRateInletVelocity;
        volumetricFlowRate constant 500;
    }
    atmosphere
    {
        type            pressureInletOutletVelocity;
        value           uniform (0 0 0);
    }
    walls
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
  }

blockMeshDict
Code:
FoamFile
 {
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

scale   1;

vertices
(
(0 0 0)
(0 35 0)
(0 65 0)
(0 100 0)
(100 0 0)
(100 35 0)
(100 65 0)
(100 100 0)
(0 0 100)
(0 35 100)
(0 65 100)
(0 100 100)
(100 0 100)
(100 35 100)
(100 65 100)
(100 100 100)
(0 0 103.5)
(0 35 103.5)
(0 65 103.5)
(0 100 103.5)
(100 0 103.5)
(100 35 103.5)
(100 65 103.5)
(100 100 103.5)
);

blocks
(
hex (0 1 9 8 4 5 13 12) (11 33 33) simpleGrading (1 1 1)
hex (1 2 10 9 5 6 14 13) (11 33 33) simpleGrading (1 1 1)
hex (2 3 11 10 6 7 15 14) (11 33 33) simpleGrading (1 1 1)
hex (8 9 17 16 12 13 21 20) (11 4 33) simpleGrading (1 1 1)
hex (9 10 18 17 13 14 22 21) (11 4 33) simpleGrading (1 1 1)
hex (10 11 19 18 14 15 23 22) (11 4 33) simpleGrading (1 1 1)

);

edges
(
);

boundary
(
 inlet
 {
  type patch;
  faces
  (
   (9 17 18 10)
  );
 }
 walls
 {
  type wall;
  faces
  (
   (0 8 9 1)
   (1 9 10 2)
   (2 10 11 3)
   (3 11 15 7)
   (7 15 14 6)
   (6 14 13 5)
   (5 13 12 4)
   (3 7 6 2)
   (2 6 5 1)
   (1 5 4 0)
   (0 4 12 8)
   (8 16 17 9)
   (10 18 19 11)
   (11 19 23 15)
   (15 23 22 14)
   (14 22 21 13)
   (13 21 20 12)
   (8 12 20 16)
  );
 }
 atmosphere
 {
  type patch;
  faces
  (
   (19 18 22 23)
   (18 17 21 22)
   (17 16 20 21)

  );
 }
 );
However, after 2000 seconds, the container was only one-third full (see figure.), the inlet is 30 x 3.5m, is in red in the top of container (see figure.) Does anyone know what is going on or what am I doing wrong?. Thanks in advance.
Attached Images
File Type: jpg Image.jpg (69.2 KB, 20 views)

Last edited by 4lrdyD; March 31, 2022 at 13:53. Reason: small corrections
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Old   April 4, 2022, 08:12
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What is the flow rate that you're seeing in your model? Have you also tried setting up the BC as it is shown in the documentation?



https://www.openfoam.com/documentati...ctorField.html
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Old   April 4, 2022, 22:07
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Quote:
Originally Posted by 37269 View Post
What is the flow rate that you're seeing in your model? Have you also tried setting up the BC as it is shown in the documentation?


https://www.openfoam.com/documentati...ctorField.html
Hi, the flow rate is not shown explicitly in the simulation, instead, what we can see is an equivalent velocity. The main velocity (x direction), has a value of 4.7619 (Q/A=500/(30x3.5), see first fig), but only in the center of patch but no in the edges, this is probably the reason why the tank does not fill. when I refine the mesh on inlet, it returns better results.


Regarding BC, I changed the inlet BC to:
Code:
    inlet
    {
        type            flowRateInletVelocity;
        volumetricFlowRate constant 500;
        extrapolateProfile yes;
        value           uniform (0 0 0);
    }
also improve the result but still the container does not fill. In this case the velocity is not 4.7619, it varies at different points of the patch (max around 23 in x direction), which has confused me a bit more since the expected speed is 500/(30x3.5)=4.7619 (See second fig). For now, what I think I should do is further refine the inlet and maybe after understanding it better, add
Code:
extrapolateProfile yes;
in the BC. Thanks for response.
Attached Images
File Type: jpg fig1.jpg (73.7 KB, 9 views)
File Type: png fig2.png (170.7 KB, 6 views)
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