| tayo |
January 18, 2014 11:57 |
3 Attachment(s)
Thanks for the response. Below is my boundary condition
Temp.: fixedGradient on wall, fixedValue inlet, zeroGradient outlet
Pressure: zeroGradient inlet and wall, fixedValue outlet
Velocity: no slip wall, fixedValue inlet, zeroGradient outlet
Here is my fvScheme:
Code:
ddtSchemes
{
default Euler;
}
gradSchemes
{
default Gauss linear;
}
gradSchemes
{
default Gauss linear;
}
divSchemes
{
div(rho*phi,U) Gauss limitedLinearV 1;
div(phi,T) Gauss upwind;
div(phi,p_rgh) Gauss upwind;
div(phi,alpha) Gauss vanLeer01;
div(phirb,alpha) Gauss interfaceCompression;
: : :
}
The checkMesh also seems ok:
Code:
Create time
Create polyMesh for time = 0
Time = 0
Mesh stats
points: 93636
faces: 267729
internal faces: 254991
cells: 87120
boundary patches: 3
point zones: 0
face zones: 0
cell zones: 1
Overall number of cells of each type:
hexahedra: 87120
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0
Checking topology...
Boundary definition OK.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Checking patch topology for multiply connected surfaces ...
Patch Faces Points Surface topology
inlet 2640 2754 ok (non-closed singly connected)
outlet 2640 2754 ok (non-closed singly connected)
heatWall 7458 7684 ok (non-closed singly connected)
Checking geometry...
Overall domain bounding box (0 0 0) (0.02 0.01 0.01)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (3.88444e-16 1.23164e-16 -3.56799e-15) OK.
Max cell openness = 8.82326e-17 OK.
Max aspect ratio = 1.33333 OK.
Minumum face area = 7.5e-08. Maximum face area = 1.0101e-07. Face area magnitudes OK.
Min volume = 2.27273e-11. Max volume = 2.52525e-11. Total volume = 2e-06. Cell volumes OK.
Mesh non-orthogonality Max: 0 average: 0
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.000109995 OK.
Coupled point location match (average 0) OK.
Mesh OK.
Time = 0.0005
Mesh stats
points: 95614
faces: 272670
internal faces: 259779
cells: 88618
boundary patches: 3
point zones: 0
face zones: 0
cell zones: 1
Overall number of cells of each type:
hexahedra: 88339
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 279
Checking topology...
Boundary definition OK.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Checking patch topology for multiply connected surfaces ...
Patch Faces Points Surface topology
inlet 2640 2754 ok (non-closed singly connected)
outlet 2640 2754 ok (non-closed singly connected)
heatWall 7611 7859 ok (non-closed singly connected)
Checking geometry...
Overall domain bounding box (0 0 0) (0.02 0.01 0.01)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-4.07224e-16 3.9387e-17 -3.50976e-15) OK.
Max cell openness = 1.76465e-16 OK.
Max aspect ratio = 1.33336 OK.
Minumum face area = 4.6875e-09. Maximum face area = 1.01015e-07. Face area magnitudes OK.
Min volume = 3.55078e-13. Max volume = 2.52538e-11. Total volume = 2e-06. Cell volumes OK.
Mesh non-orthogonality Max: 29.6211 average: 1.53168
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.334633 OK.
Coupled point location match (average 0) OK.
Mesh OK.
The issue seems to be with the gradScheme. It gives fairly the same result when for fvc::grad(T) and fvc::grad(T-TSat) where TSat is a dimensionedScalar at 371K while T is a volScalarField defined in previous post.
Code:
volScalarField gradT = mag(fvc::grad(T));
volScalarField gradTt = mag(fvc::grad(T-TSat));
Info << min(gradT) << max(gradT) << min(gradTt) << max(gradTt) << endl;
Checking the min. & max. values for mag(grad(T)) and mag(grad(T-TSat) shows that they are exactly the same. This is clearly wrong but I don't understand why. However, when I compute these values by postprocessing with funkySetField, I get more reasonable result as shown in the plots. So my question is this: why are these two grad(T-TSat) results significantly different? How do I best define grad(T-TSat) to give the expected result? Thanks |
