New Code Saturne tutorial online
- Claus
-
Topic Author
- Offline
- Moderator
-
Less
More
- Posts: 670
- Thank you received: 34
16 years 1 week ago #2826
by Claus
Code_Aster release : STA11.4 on OpenSUSE 12.3 64 bits - EDF/Intel version
Replied by Claus on topic Re:New Code Saturne tutorial online
When I change the pressure from 1kPa to 0.7kPa in my MachCAD doc. I get a theoretical exit speed of 32.142[m/s] so the ballparking of 33[m/s] seems ok.
About the flow rate from the flowmeter: well I'm not sure what relative density to use, because I don't know the exact composition of the natural gas we use here - it actually differs quite a lot from place to place so pure methane was used. Second, it is taken from a table at 20c or 25c (I forget right now) so that has an impact as well.
Another thing that has a small impact, is the shape of the modeled nozzle, it doesn't entirely correspond to the real world one.
All in all - lots of variables
I also tried using compressibility earlier,but failed - maybe *SOMEONE* (hint) could give us an example.
I've gotten an older copy of the Crane doc. I'll have a look at it - maybe I'll be inclined to buy it later.
Oh yeah, feel free to post the .hdf, I'd like to see what kind of mesh you created.
About the flow rate from the flowmeter: well I'm not sure what relative density to use, because I don't know the exact composition of the natural gas we use here - it actually differs quite a lot from place to place so pure methane was used. Second, it is taken from a table at 20c or 25c (I forget right now) so that has an impact as well.
Another thing that has a small impact, is the shape of the modeled nozzle, it doesn't entirely correspond to the real world one.
All in all - lots of variables

I also tried using compressibility earlier,but failed - maybe *SOMEONE* (hint) could give us an example.
I've gotten an older copy of the Crane doc. I'll have a look at it - maybe I'll be inclined to buy it later.
Oh yeah, feel free to post the .hdf, I'd like to see what kind of mesh you created.
Code_Aster release : STA11.4 on OpenSUSE 12.3 64 bits - EDF/Intel version
- Robin Borland
- Offline
- Senior Member
-
Less
More
- Posts: 48
- Thank you received: 0
16 years 1 week ago #2829
by Robin Borland
Replied by Robin Borland on topic Re:New Code Saturne tutorial online
Claus,
My files uploaded are located here:
www.caelinux.org/wiki/index.php/Special:Imagelist
A few notes on these:
1. It seems that the previous simulations ( yours and mine) are off on the density - we both inadvertantly used SG instead of density in Kg/M^3 - per the Crane book, a typical value for a typical natural gas composition is 0.8034 Kg/M^3
2. I used 1.25 *10^-5 for the absolute viscosity
3. My mesh is coarse - 0.5mm tet mesh - it could be finer, but I don't have a lot of computer horsepower at present, or I would refine it.
4. The simulations done are close to your real world results - any differences are probably due to mesh density ( accuracy), and geometry differences between what was tested and what was modelled.
5. The updated Mathcad file with the density correction is attached to this post, I also added the Re number check.
Again - thanks for your efforts on this, I have found it useful to be able to compare text book predictions, with what CFD results are vs. your real world tests.
Regards
Robin
PS: I did get a sample file from Code Saturne Support of a compressibility example, I did not look at it yet in any great amount of detail - it uses a mesh file format that I am not familiar with, but you can look at the extra Fortran files that they used -
I will post it to the Wiki also in case anyone else wants to look at it.<br /><br />Post edited by: Robin Borland, at: 2009/04/22 17:16
My files uploaded are located here:
www.caelinux.org/wiki/index.php/Special:Imagelist
A few notes on these:
1. It seems that the previous simulations ( yours and mine) are off on the density - we both inadvertantly used SG instead of density in Kg/M^3 - per the Crane book, a typical value for a typical natural gas composition is 0.8034 Kg/M^3
2. I used 1.25 *10^-5 for the absolute viscosity
3. My mesh is coarse - 0.5mm tet mesh - it could be finer, but I don't have a lot of computer horsepower at present, or I would refine it.
4. The simulations done are close to your real world results - any differences are probably due to mesh density ( accuracy), and geometry differences between what was tested and what was modelled.
5. The updated Mathcad file with the density correction is attached to this post, I also added the Re number check.
Again - thanks for your efforts on this, I have found it useful to be able to compare text book predictions, with what CFD results are vs. your real world tests.
Regards
Robin
PS: I did get a sample file from Code Saturne Support of a compressibility example, I did not look at it yet in any great amount of detail - it uses a mesh file format that I am not familiar with, but you can look at the extra Fortran files that they used -
I will post it to the Wiki also in case anyone else wants to look at it.<br /><br />Post edited by: Robin Borland, at: 2009/04/22 17:16
- Robin Borland
- Offline
- Senior Member
-
Less
More
- Posts: 48
- Thank you received: 0
16 years 1 week ago #2830
by Robin Borland
Replied by Robin Borland on topic Re:New Code Saturne tutorial online
Matchcad file attached
Attachment Orifice_Flow_gas-a0082d9355d9347bead7ee7e6b1a7dee.rar not found
- Claus
-
Topic Author
- Offline
- Moderator
-
Less
More
- Posts: 670
- Thank you received: 34
16 years 1 week ago #2844
by Claus
Code_Aster release : STA11.4 on OpenSUSE 12.3 64 bits - EDF/Intel version
Replied by Claus on topic Re:New Code Saturne tutorial online
Thanks for your reply - Unfortunately I don't have the time atm. to update the wiki nor rerun the simulation, maybe later on I'll get it done - In the meantime I'll link to this thread on the wiki so people can view the discussion.
Code_Aster release : STA11.4 on OpenSUSE 12.3 64 bits - EDF/Intel version
- florante
- Offline
- Senior Member
-
Less
More
- Posts: 50
- Thank you received: 0
14 years 9 months ago #4483
by florante
Replied by florante on topic Re:New Code Saturne tutorial online
Claus,
I like your tutorial but I found it a bit pain reading it in wiki. So I did a presentation out of it and I think this is more readable/printable
See attached.
thanks
Post edited by: florante, at: 2010/07/27 18:44<br /><br />Post edited by: florante, at: 2010/07/27 19:05
I like your tutorial but I found it a bit pain reading it in wiki. So I did a presentation out of it and I think this is more readable/printable
See attached.
thanks
Post edited by: florante, at: 2010/07/27 18:44<br /><br />Post edited by: florante, at: 2010/07/27 19:05
- florante
- Offline
- Senior Member
-
Less
More
- Posts: 50
- Thank you received: 0
14 years 9 months ago #4484
by florante
Replied by florante on topic Re:New Code Saturne tutorial online
[file] florante wrote:
<br /><br />Post edited by: florante, at: 2010/07/27 19:13Claus,
I like your tutorial but I found it a bit pain reading it in wiki. So I did a presentation out of it and I think this is more readable/printable
See attached.
thanks
Post edited by: florante, at: 2010/07/27 18:44<br /><br />Post edited by: florante, at: 2010/07/27 19:05
Moderators: catux
Time to create page: 0.153 seconds