icoFOAM don't calculate right
Hello FOAM users,
Recently I use icoFOAM to claculate a channel flow,like the picture show, I use ICEM to make a struct-mesh,see below. http://h.hiphotos.baidu.com/album/s%...44ac34828a.jpg Later,I use icoFOAM,one of the two pipes is inlet another is outlet. But I failed.After 2000 steps,It shows that the velocity still stay at inlet,like the picture shows.The red only can be see at one pipe. http://b.hiphotos.baidu.com/album/s%...f9d62aa08a.jpg Please,Who can tell me why? Thanks. |
My first quick guess would be:
You set the channel walls to "wall" - which usually means the velocity at the boundary is "uniform (0 0 0)". Have you had a look at a cross-section through the channel? There might be high flow velocities in the middle of the channel. This is what you see at the inlet cross-section, too. ;) |
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http://b.hiphotos.baidu.com/album/s%...b1ca137074.jpg |
Well, at least there IS a flow profile. Please post your BC files, especially p and U! ;)
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---------------------------------------------------------------------------------------------------------------------------- FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { inletWall { type zeroGradient; } outletWall { type fixedValue; value uniform 101.630; } upWalls { type zeroGradient; } inPipe { type zeroGradient; } outPipe { type zeroGradient; } downWalls { type zeroGradient; } outerWalls { type zeroGradient; } } --------------------------------------------------------------------------------------------------------------------------- FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { inletWall { type fixedValue; value uniform (0 0 -1.9099); } outletWall { type zeroGradient; } upWalls { type fixedValue; value uniform (0 0 0); } inPipe { type fixedValue; value uniform (0 0 0); } outPipe { type fixedValue; value uniform (0 0 0); } downWalls { type fixedValue; value uniform (0 0 0); } outerWalls { type fixedValue; value uniform (0 0 0); } } // ************************************************** *********************** // |
Okay, first thing I see is your inlet velocity.
(0 0 -1.9099) points in negative Z-direction which is, according to the coordinate system, orthogonal to your inlet patch - because Y is the vertical axis! Try (0 -1.9099 0). And why is your pressure at the outlet so much higher than in the internal field? Uniform 0 for internal field means you've got ambient pressure level in the internal. Uniform 101.630 at the outlet means you've got 101.63 N/mē overpressure at the outlet. This probably won't work if you want the fluid to leave your channel at this patch. I suggest you try uniform 0 there, too. Hope this will fix your problem. |
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I get the reason now. |
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