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PolySpline question

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Old   October 1, 2008, 07:37
Default Hello! I have a problem usi
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Steinar Aasebų
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Hello!

I have a problem using the polySpline in blockMesh, does anyone know the syntax that must be used? It have not found it anywhere!

Thanks,

Steinar
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Old   October 2, 2008, 06:39
Default If I remember correctly the sy
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Martin Aunskjaer
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If I remember correctly the syntax is

polySpline pntA pntB ( (ctrl1) (ctrl2) ... (ctrlN) ) grad_pntA grad_pntB;

where (pntA,grad_pntA) and (pntB,grad_pntB) are the coordinates and the gradients at the end points of the curve, and the (ctrl) are controlpoints.

Use the search facility to search for polySpline. I recall reading about it in the forum.
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Old   October 2, 2008, 07:15
Default Yes, this syntax is accepted b
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Steinar Aasebų
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Yes, this syntax is accepted by blockMesh, but the gradients are giving me unexpected results.

I really think I need some kind of B-splines to avoid the disturbances near the end points, and they are not implemented in OF?
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Old   October 2, 2008, 09:52
Default go to the bugs list there is t
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Franz
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go to the bugs list there is the solution or
search for "Bugs in polySplineEdge.C"
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Old   October 2, 2008, 11:08
Default What kind of unexpected result
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Martin Aunskjaer
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What kind of unexpected results? If you mean erratic shapes, like loops, this may happen for unevenly spaced data points if the algorithm that calculates the control points assigns uniformly spaced parameter values to the data points.

Looking at the implementation in

applications/utilities/mesh/generation/blockMesh/curvedEdges

this does indeed appear to be the case. You could try to specify the gradients to zero in which case polySpline calculates them as a finite-difference (Catmull-Rom).

polySpline in OpenFOAM is a clamped cubic B-Spline.
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Old   December 4, 2008, 09:10
Default Dear Martin, I got trouble
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Wolfgang Heydlauff
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Dear Martin,

I got trouble with the polySpline as well. Poorly I did not understand any word of what you said.

HOW can I get the polySpline work?

The polySpline works fine at the beginning. but towards the end point it starts to become a straight line. the given gradient is ignored as well.

..?

Thanks
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