[gschaider]

Originally Posted by enr_venkat

Hi everyone,

I'm a new registered user in CFD-Online.

No offense: are you sure you're in the right Forum (OpenFOAM)? I don't see the relevance of your posting to the Thread you posted it in

Originally Posted by enr_venkat

I would like to calculate theoretically the mass flow rate of air that pass through EGR Valve at different Valve seats positioningi.e. 1mm, 2mm, 3mm, 4mm, 5mm.. As i understand, the flow rate would increase gradually as the valve lift increases. I have the experimental data i.e. at 1mm valve lift, the mass flow rate is observed to be 6 - 8 kg/hr and at 7mm, flow rate is observed to be 10 kg/hr. My client wants to compare the theoretical calculation. Moreover, the flow is assumed to be incompressible as the density is constant with time.

Known values - Pressure drop (2 kpa), valve lift position (1mm to 7mm), Exhaust temperature 20 C, EGR Dia - 30 mm

Mass flow rate to be calculated : ?

I'm looking for an incompressible flow rate equation using which we could calculate flow rate. Please do the neeful

[gschaider]

Originally Posted by anger

Hello Bernhard,

yes, it is a plain ascii file.
The reason for using SolutionFile is that my first trial with PPF was on a binary file which failed so I thought this class could not be used for my task.

Plus that the example on the Wiki was done using ancient technology (SolutionFile). I'll have to rewrite that one of these days. Or somebody else will feel like it

Bernhard

[enr_venkat]

Hi every one,

Please direct me to right thread where my theoritical problem solving question fits. I thought i replied to CFD WiKi. But I'm not sure after checking replies from others. Please do guide me at the earliest.

Many thanks

[bastil]

Hi Bernhard,

how can I try using matplotlib instead of gnuplot with pyFoamPlotWatcher.py from 0.5.3, please? Thanks.

BastiL

[anger]

Originally Posted by gschaider

Yep. That is handled transparently.



I'll have a look. The problem is that SolutionFile is a legacy class that existed before ParsedParameterFile. These days I do most of this stuff with PPF. SolutionFile only has a performance advantage if you're handling files with large non-uniform fields, in all other case PPF is preferred because it is much more flexible and robust

BTW: The problem occurs with a "plain" file or is there some binary data in it?

Bernhard

Hello Bernhard,

I think the error was that I used ancient syntax:
value 101300 instead of
value uniform 101300.

Regards,
-Thomas

[gschaider]

Originally Posted by bastil

Hi Bernhard,

how can I try using matplotlib instead of gnuplot with pyFoamPlotWatcher.py from 0.5.3, please? Thanks.

Use the flag --implementation=matplotlib

If it works for you, could you extend the Wiki-page so that future generations will benefit from it. Thanks

[bastil]

Originally Posted by gschaider

Use the flag --implementation=matplotlib

If it works for you, could you extend the Wiki-page so that future generations will benefit from it. Thanks

Does not work for me. What versions of matplotlib are know to work?

[gschaider]

Originally Posted by bastil

Does not work for me.

Could you be a little bit more specific

Originally Posted by bastil

What versions of matplotlib are know to work?

With 0.99.1.1 on my MacBook I get windows (and hardcopies). With 0.98.5.3 on my CentOS/RedHat-machines only hardcopies (try that switch) work

Bernhard

[bastil]

Originally Posted by gschaider

Could you be a little bit more specific

We currelty have matplotlib 0.98.5.2 running. I get:

  PyFoam FATAL ERROR on line 44 of file /opt/PyFoam/PyFoam-0.5.3//lib64/python2.4/site-packages/PyFoam/Basics/MatplotlibTimelines.py : Matplotlib not installed

on your master node even though I can import matplotlib from within python without any problems..
On my local machine this changes to:

PyFoam WARNING on line 42 of file /opt/PyFoam/PyFoam-0.5.3//lib64/python2.4/sit
e-packages/PyFoam/Basics/MatplotlibTimelines.py : Matplotlib-Version does not support SubplotHost

Regards

[gschaider]

Originally Posted by bastil

We currelty have matplotlib 0.98.5.2 running. I get:

  PyFoam FATAL ERROR on line 44 of file /opt/PyFoam/PyFoam-0.5.3//lib64/python2.4/site-packages/PyFoam/Basics/MatplotlibTimelines.py : Matplotlib not installed

on your master node even though I can import matplotlib from within python without any problems..

Have a look whether
import matplotlib.pyplot as plt
works there. That is the second package that is imported in that module

Originally Posted by bastil

On my local machine this changes to:

PyFoam WARNING on line 42 of file /opt/PyFoam/PyFoam-0.5.3//lib64/python2.4/sit
e-packages/PyFoam/Basics/MatplotlibTimelines.py : Matplotlib-Version does not support SubplotHost

Regards

This is OK. It says that on my Linux-machine, too. That (SubPlotHost) is a feature that obviously only exists in 0.99.

The only thing that in my experience works with 0.98 is hardcopies with the hardcopy-option (you won't see any "live" windows)

Bernhard

[braennstroem]

Hi,

I try to adjust the inlet turbulent kinetic energy in the changeDictionaryDict with pyFoamWriteDictionary:

pyFoamWriteDictionary.py system/changeDictionaryDict "dictionaryReplacement['k']['boundaryField']['inlet']['value']" "uniform 100"

This command works fine, except, that I get thos quotes in my dictionary file, which I do not want... maybe there is a way to access the 'uniform' value directly or an option to prevent pyFoam from printing those quotes into the dictionary? Would be nice!

Fabian

[gschaider]

Originally Posted by braennstroem

Hi,

I try to adjust the inlet turbulent kinetic energy in the changeDictionaryDict with pyFoamWriteDictionary:

pyFoamWriteDictionary.py system/changeDictionaryDict "dictionaryReplacement['k']['boundaryField']['inlet']['value']" "uniform 100"

This command works fine, except, that I get thos quotes in my dictionary file, which I do not want... maybe there is a way to access the 'uniform' value directly or an option to prevent pyFoam from printing those quotes into the dictionary? Would be nice!

Fabian

Hi Fabian!

See https://sourceforge.net/apps/mantisb.../view.php?id=5 for news on this bug.

Bernhard

PS: In the future bugs that are reported via Mantis will get priority treatment (it is hard to keep track whether there is another problem hidden in this thread as it is getting rather long)

[braennstroem]

Hi Bernhard,

thanks, I did not know this.

Fabian

[braennstroem]

Hi Bernhard,

me again :-)
For preprocessing I am using your pyFoamCreateBoundaryPatches tool. It seems, that it does not work in parallel for snappyHexMesh-paralllel-created meshes!? Would be nice, if this works!

Fabian

[gschaider]

Originally Posted by braennstroem

Hi Bernhard,

thanks, I did not know this.

You can't (have known). The bug-tracker is only in operation for a week and was not properly announced

Bernhard

[gschaider]

Originally Posted by braennstroem

For preprocessing I am using your pyFoamCreateBoundaryPatches tool. It seems, that it does not work in parallel for snappyHexMesh-paralllel-created meshes!? Would be nice, if this works!

As I said above: Report an issue at http://sourceforge.net/apps/mantisbt...e_status_id=90 (Severity=feature) and it might be considered

Bernhard

[braennstroem]

Yes, was not sure, if this feature is available.

Fabian

[braennstroem]

Hi Bernhard,

I am trying to read the boundary files using pyFoam. This works quite nice with this simple script:

import fnmatch
from PyFoam.RunDictionary.BoundaryDict import BoundaryDict
from PyFoam.RunDictionary.SolutionDirectory import SolutionDirectory

case="."
case2="processor0"
#proc="processor0"
# pfile=SolutionDirectory(case, archive=None, paraviewLink=False).boundaryDict(time="constant",p rocessor=proc)
# print pfile

pfile=BoundaryDict(case2)
for p in pfile.patches():
if (fnmatch.fnmatch(p, 'IN*') or fnmatch.fnmatch(p, 'in*')):
print "Inlet: ", p
if fnmatch.fnmatch(p, 'OUT*'):
print "Outlet: ", p
if fnmatch.fnmatch(p, 'cyc-*'):
print "Cyclic Boundary: ", p
if fnmatch.fnmatch(p, 'sym-*'):
print "SymmetryPlane: ", p
if fnmatch.fnmatch(p, 'w-*'):
print "Wall: " ,p

bfile=BoundaryDict(case)
for b in bfile.patches():
print b

Unfortunately, I have no idea, how I could read the boundary file in a time directory without the 'needed' constant directory!?
Would be nice, if you have a hint!
Fabian

[gschaider]

Originally Posted by braennstroem

Hi Bernhard,

I am trying to read the boundary files using pyFoam. This works quite nice with this simple script:



Unfortunately, I have no idea, how I could read the boundary file in a time directory without the 'needed' constant directory!?
Would be nice, if you have a hint!
Fabian

I don't understand the question. You're working with a moving mesh and want to access the boundary file for a specific time, right? The parameter time="constant" is not needed in the usual case as a default is defined for that. To get the boundary-File case/666/polyMesh/boundary the option time="666" should be sufficient

Bernhard

[braennstroem]

Hi Bernhard,
yes, you are right. Though, where do I set the option? Using:

pfile=BoundaryDict(case2,time="10")

I get: TypeError: __init__() got an unexpected keyword argument 'time'

Thanks for your help!
Fabian