[OpenFOAM] 0-velocity countour paraFoam

ArathoN · October 15, 2014, 13:18

I've simulated the backward facing step and i wanted to show the 0-velocity contour in the circulating region but i have no idea how to do it. Any help?

ArathoN · October 17, 2014, 03:30

no one has an idea? I searched a method to isolate/trace the cells with zero velocity but found nothing.

tomf · October 21, 2014, 15:06

Hi,

First you should use the calculator filter to generate a scalar variable magU, which you can than use to generate a contour (with value 0) with the contour filter.

Regards,
Tom

ArathoN · October 21, 2014, 20:48

Quote:

Originally Posted by tomf

Hi,

First you should use the calculator filter to generate a scalar variable magU, which you can than use to generate a contour (with value 0) with the contour filter.

Regards,
Tom

I can't create a countour for magU = 0 it gave me this error:

Code:

Warning: In /home/opencfd/OpenFOAM/ParaView-4.1.0/ParaViewCore/ServerManager/Rendering/vtkSMPVRepresentationProxy.cxx, line 279
vtkSMPVRepresentationProxy (0x75b45f0): Could not determine array range.

do you have an idea how to solve this? If you want i can pass you a case.

tomf · October 22, 2014, 03:14

Hi,

I thought about this and came to the conclusion that maybe there is no cell centre where the velocity magnitude is exactly 0? This would not be strange since we are interpolating between values that are strictly nonnegative and discrete. So unless there is a cell with a magnitude of 0 there is probably no contour to be created. Maybe instead of the magnitude you could calculate the velocity in the freestream direction and make a contour of that. This could be negative at some locations (reversed flow) meaning that you could have a value of 0 in your interpolation.

Regards,
Tom

ArathoN · October 22, 2014, 13:27

I've done that with the stream tracer and you'll see the recirculating region, however you can't isolate the "line" with 0-velocity that separates the recirculating region from the outer flow. Still no idea on how to define that streamline.

I've also been thinking of a way to define the center of the circulation region other than seeing the flow pattern and guess its position.

October 15, 2014, 13:18	0-velocity countour paraFoam	#1
ArathoN Senior Member ArathoN Join Date: Jul 2011 Posts: 137 Rep Power: 15	I've simulated the backward facing step and i wanted to show the 0-velocity contour in the circulating region but i have no idea how to do it. Any help?

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October 17, 2014, 03:30		#2
ArathoN Senior Member ArathoN Join Date: Jul 2011 Posts: 137 Rep Power: 15	no one has an idea? I searched a method to isolate/trace the cells with zero velocity but found nothing.

October 21, 2014, 15:06		#3
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 634 Rep Power: 32	Hi, First you should use the calculator filter to generate a scalar variable magU, which you can than use to generate a contour (with value 0) with the contour filter. Regards, Tom

October 22, 2014, 03:14		#5
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 634 Rep Power: 32	Hi, I thought about this and came to the conclusion that maybe there is no cell centre where the velocity magnitude is exactly 0? This would not be strange since we are interpolating between values that are strictly nonnegative and discrete. So unless there is a cell with a magnitude of 0 there is probably no contour to be created. Maybe instead of the magnitude you could calculate the velocity in the freestream direction and make a contour of that. This could be negative at some locations (reversed flow) meaning that you could have a value of 0 in your interpolation. Regards, Tom

October 22, 2014, 13:27		#6
ArathoN Senior Member ArathoN Join Date: Jul 2011 Posts: 137 Rep Power: 15	I've done that with the stream tracer and you'll see the recirculating region, however you can't isolate the "line" with 0-velocity that separates the recirculating region from the outer flow. Still no idea on how to define that streamline. I've also been thinking of a way to define the center of the circulation region other than seeing the flow pattern and guess its position.