Colour by turbulence intensity?

dxg169 · February 24, 2015, 11:17

Hello all,

Does anybody know how I can colour a slice by turbulence intensity? For example in the U0 direction: I have UPrime2Mean:0 and I have UMean:0, although I want to somehow get the paraView to compute the TI = (SQRT(UPrime2Mean)/UMean) and then colour the slice based on these values?

I'm relatively new to paraview so have tried but can't seem to crack this one.

Best wishes,
D

tomf · February 25, 2015, 09:44

Hi D,

This sounds like you would need the calculator filter.

Filters>alphabetical>Calculator

Or click on the calculator filter icon.

Than use the scalar UPrime2Mean_X (or Y or Z) and the corresponding scalar UMean_X (or Y or Z) as the function. The result should read TI.

Or do you want to have the magnitude of the mean and variance? In that case use mag(UPrime2Mean) and mag(UMean).

Hope this helps.

Regards,
Tom

dxg169 · February 25, 2015, 10:39

Quote:

Originally Posted by tomf

Hi D,

This sounds like you would need the calculator filter.

Filters>alphabetical>Calculator

Or click on the calculator filter icon.

Than use the scalar UPrime2Mean_X (or Y or Z) and the corresponding scalar UMean_X (or Y or Z) as the function. The result should read TI.

Or do you want to have the magnitude of the mean and variance? In that case use mag(UPrime2Mean) and mag(UMean).

Hope this helps.

Regards,
Tom

Hi tom, Thank you for the reply. I'm having some issues with the solution. I've attached a screen shot of my error message and the formula you can see I'm trying to us in the calculator.

I'm basically trying to calculate the Turbulence Intensity at points on a slice. I'm trying to compute the TI using the UPrime2Mean:0 and UMean:0.

What i'm after is for the post processor to calculate the TI for all the points on the slice, and then I'm hoping to colour that slice using the TI results.

Any ideas?

tomf · February 25, 2015, 11:15

From your screenshot I cannot read the function. Can you just literally copy it here? Maybe use the Code tags like I did below.

Based on what I can see I think it should be:

Code:

sqrt(UPrime2Mean_XX)/UMean_X

Also in the Result Array Name box you should specify TI instead of Result.

dxg169 · February 25, 2015, 11:19

Quote:

Originally Posted by tomf

From your screenshot I cannot read the function. Can you just literally copy it here? Maybe use the Code tags like I did below.

Based on what I can see I think it should be:

Code:

sqrt(UPrime2Mean_XX)/UMean_X

Also in the Result Array Name box you should specify TI instead of Result.

I've used the same code as above: sqrt(UPrime2Mean_XX)/UMean_X

although my error message reads as follows:

ERROR: In /gpfs/apps/OpenFOAM/ThirdParty-2.1.1/ParaView-3.12.0/VTK/Common/vtkFunctionParser.cxx, line 1480
vtkFunctionParser (0x145790fb0): Syntax error: operator expected; see position 18

ERROR: In /gpfs/apps/OpenFOAM/ThirdParty-2.1.1/ParaView-3.12.0/VTK/Common/vtkFunctionParser.cxx, line 1480
vtkFunctionParser (0x145790fb0): Syntax error: operator expected; see position 18

Warning: In /gpfs/apps/OpenFOAM/ThirdParty-2.1.1/ParaView-3.12.0/VTK/Graphics/vtkArrayCalculator.cxx, line 401
vtkPVArrayCalculator (0x145c199f0): An error occured when parsing the calculator's function. See previous errors.

tomf · February 26, 2015, 04:50

I see you are using version 3.12.0 of ParaView, maybe this was a bug in that version, could you try using the latest ParaView (4.3.1)? The error message seems to indicate it needs an operator at the _XX position, but that does not really make sense to me.

February 24, 2015, 11:17	Colour by turbulence intensity?	#1
dxg169 New Member Join Date: Feb 2015 Posts: 6 Rep Power: 11	Hello all, Does anybody know how I can colour a slice by turbulence intensity? For example in the U0 direction: I have UPrime2Mean:0 and I have UMean:0, although I want to somehow get the paraView to compute the TI = (SQRT(UPrime2Mean)/UMean) and then colour the slice based on these values? I'm relatively new to paraview so have tried but can't seem to crack this one. Best wishes, D

February 25, 2015, 11:15		#4
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 647 Rep Power: 32	From your screenshot I cannot read the function. Can you just literally copy it here? Maybe use the Code tags like I did below. Based on what I can see I think it should be: Code: sqrt(UPrime2Mean_XX)/UMean_X Also in the Result Array Name box you should specify TI instead of Result. hulli likes this. Last edited by tomf; February 25, 2015 at 11:16. Reason: Remark about TI vs Result

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February 25, 2015, 09:44		#2
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 647 Rep Power: 32	Hi D, This sounds like you would need the calculator filter. Filters>alphabetical>Calculator Or click on the calculator filter icon. Than use the scalar UPrime2Mean_X (or Y or Z) and the corresponding scalar UMean_X (or Y or Z) as the function. The result should read TI. Or do you want to have the magnitude of the mean and variance? In that case use mag(UPrime2Mean) and mag(UMean). Hope this helps. Regards, Tom

February 26, 2015, 04:50		#6
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 647 Rep Power: 32	I see you are using version 3.12.0 of ParaView, maybe this was a bug in that version, could you try using the latest ParaView (4.3.1)? The error message seems to indicate it needs an operator at the _XX position, but that does not really make sense to me.