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What are the variables "conservative_"?

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Old   November 5, 2013, 02:41
Question What are the variables "conservative_"?
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Sreekanth
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Hi,
I am using SU2 V2.0.7
1.When the result of turbulent flow over flat plate is opened in ParaView, I see that there are variables "conservative_1","conservative_2"...."conservative _5". What are these variables?
2.Where is velocity? This used to be there with SU2 V2.0.0
3.Which one is density?

Sreekanth
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Old   November 5, 2013, 19:57
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Thomas D. Economon
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Hi Sreekanth,

The conservative variables for the governing flow equations (Euler, N-S, RANS) are the mass, momentum, and energy, i.e. U = ( density, density*velocity, density*energy)^T. Therefore, the density is the first conservative variable, and in order to get the velocity, you should divide the momentum components by the density. In 2-D, for example, the x-velocity would then be vel_x = Conservative_2/Conservative_1.

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Tom
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Old   December 19, 2013, 14:10
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Hi,
Based on the above explanation , I would have 4 conservatives for a 2D problem and 5 for 3D problem.
I did a 2D problem in SU2 with Physical_problem = Navier stokes and KIND_TURB_MODEL= SA
I get 5 conservative variables .
If its a 3D problem, I get 6 conservatives. Which is the extra conservative variable calculated?
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Old   December 19, 2013, 17:15
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Quote:
Originally Posted by shsreekanth View Post
Hi,
Based on the above explanation , I would have 4 conservatives for a 2D problem and 5 for 3D problem.
I did a 2D problem in SU2 with Physical_problem = Navier stokes and KIND_TURB_MODEL= SA
I get 5 conservative variables .
If its a 3D problem, I get 6 conservatives. Which is the extra conservative variable calculated?
Dear, I suggest u should read some books on Fluid dynamics or CFD.
The extra conservative variable is eddy-viscosity variable in SA turbulent model.

Merry Xmas and happy new year.

Good Luck
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Old   December 20, 2013, 04:08
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Thanks
Merry X'mas and Happy new year
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Old   February 23, 2014, 15:03
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Hi all,

I would like to continue this thread, if I may, with a question with regard to the conservation variables.

Sreekanth mentioned that the velocity parameter has disappeared in version 3.0, while it was there in the second version. I noticed the same, which I found quite a shame. The transition also changed the output parameters of flow.vtk files. With v2.0 flow.vtk files, I was able to visualize the direction of flow or velocity with the usage of glyphs in Paraview. I haven't found a way to achieve the same with v3.0 flow.vtk files. Does anybody know how I can achieve this?

Moreover, the v3.0 flow.vtk files also seem to miss the streamline functionability in Paraview.

Do I have to convert the flow.vtk files to be able to use this functions? If yes, how can I do this?

Thanks in advance!

Niels
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Old   February 24, 2014, 02:30
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Hi,

To get the velocity vector , you have to use the filter 'calculator' in paraview. For 3D, the new variable should be "conservative2"/"conservative1"*iHat+"conservative3"/"conservative1"*jHat + "conservative4"/"conservative1"*kHat. This will give velocity vector (u,v,w) . After that, you can apply streamlines

I hope this is what you asked about.

Sreekanth
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Old   February 24, 2014, 13:01
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Quote:
Originally Posted by liujmljm View Post
dear, i suggest u should read some books on fluid dynamics or cfd.
The extra conservative variable is eddy-viscosity variable in sa turbulent model.

Merry xmas and happy new year.

Good luck
大哥您可是真犀利```
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Old   February 24, 2014, 15:16
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Quote:
Originally Posted by shsreekanth View Post
Hi,

To get the velocity vector , you have to use the filter 'calculator' in paraview. For 3D, the new variable should be "conservative2"/"conservative1"*iHat+"conservative3"/"conservative1"*jHat + "conservative4"/"conservative1"*kHat. This will give velocity vector (u,v,w) . After that, you can apply streamlines

I hope this is what you asked about.

Sreekanth
Thanks! That was indeed what I was looking for!
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Old   February 24, 2014, 16:05
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Hi,

Also, all these variables are scaled. So to get the actual value of velocity, you must multiply it with the value of reference velocity.
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