CFD Online URL
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

BC for rhoSimpleFoam

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   September 29, 2005, 14:59
Default Hi, first of all thanks for
  #1
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi,

first of all thanks for this great toolset!

I have finished to set up a case to simulate the steady compressible turbulent flow through a manifold (1 inlet, 1 outlet) with rhoSimpleFoam. The goal is to estimate the massflow through the geometry by specifying:

Inlet: Total pressure 1bar, Temperature 293.15K
outlet: Static pressure, 0.9bar

Everything seems be fine but I have still the problem of defining the right BC for this setup.
What should be specified at the inlet to reflect the above BC?

Thanks for any help,

regards
Uli
uli_u is offline   Reply With Quote

Old   September 30, 2005, 07:51
Default Sorry.. How do you set the rho
  #2
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 7
maritozzo is on a distinguished road
Sorry.. How do you set the rhoSimpleFoam solver. I compiled it but i can't find it in the FoamX case window please help me
maritozzo is offline   Reply With Quote

Old   September 30, 2005, 14:15
Default rhoSimpleFoam is probably not
  #3
Super Moderator
 
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,416
Rep Power: 15
mattijs is on a distinguished road
rhoSimpleFoam is probably not configured inside FoamX.

You'll have to edit the files by hand. Just copy and modify an existing tutorial case for one of the other solvers.
mattijs is offline   Reply With Quote

Old   September 30, 2005, 14:47
Default Hi Muzio, I have edited the
  #4
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi Muzio,

I have edited the files by hand and started the code. The informative error messages helped me to complete the configuration.

I will send you my example by mail. Just put your own mesh in, edit the BCs and start the run by calling rhoSimpleFoam <your_root> tube.

The mesh I put in is just an example, the code will die after a few steps.

Maybe you can help me to find out the BCs for my problem (Totalpressure inlet 1bar, static pressure outlet 0.9bar).

Uli
uli_u is offline   Reply With Quote

Old   October 3, 2005, 05:52
Default Hi, I have tried to create
  #5
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi,

I have tried to create a FoamX configuration for rhoSimpleFoam. Just untar it under $FOAM_SOLVERS/rhoSimpleFoam which will give you the directory FoamX with all the files needed for your first steps with rhoSimpleFoam.

rhoSimpleFoam_FoamX.tar.gz

As I am very new to Openfoam, there might be some mistakes in there but hopefully there is some expert out there who will fine tune this...

Have fun,
Regards
Uli
uli_u is offline   Reply With Quote

Old   October 3, 2005, 07:44
Default Hi again, for those who are
  #6
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi again,

for those who are interested I will add a test case for rhoSimpleFoam. It is a curved tube (meshed with netgen) with an inlet velocity of 50m/s, T=293.15K. Outlet pressure is 1bar. Create a directory under your tutorial directory, call it rhoSimpleFoam and untar the case there.

I have not finished to run this case, after a short time the calculation crashes. Neither decrease of the p-underrelaxation factor helps nor playing with the solver tolerances. Any ideas?



Regards
Uli
uli_u is offline   Reply With Quote

Old   October 3, 2005, 07:51
Default Sorry, the compressed size
  #7
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Sorry,

the compressed size of the case is 1.5MB but the board posting limit is 50k. If you are interested, drop me a mail, I will send you the case.

Uli
uli_u is offline   Reply With Quote

Old   October 4, 2005, 06:04
Default Hi Uli, did you try underre
  #8
Super Moderator
 
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,416
Rep Power: 15
mattijs is on a distinguished road
Hi Uli,

did you try underrelaxing rho? Just add an entry called 'rho' to the relaxationFactors.
mattijs is offline   Reply With Quote

Old   October 4, 2005, 09:24
Default Hi everybody , first of all ,
  #9
Member
 
Muzio Grilli
Join Date: Mar 2009
Posts: 36
Rep Power: 7
maritozzo is on a distinguished road
Hi everybody , first of all , thank you very much!!..the last file was good.. but now i have other problems.
I have to calculate lift and drag acting on a airfoil, I'm using liftDrag application but it always give me strange results.
For example i always obtain drag coefficient zero for every angle of attack and the lift coefficent is given as a vector while it should be a single value

I just think that it refers to three directions because OpenFoam is a 3d code, but i don't know how to explain myself the drag coefficient

Thank you
maritozzo is offline   Reply With Quote

Old   October 4, 2005, 13:54
Default Hi Mattijs, that was a good
  #10
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi Mattijs,

that was a good hint! I looked into the code and saw the call to rho.relax...I should have looked earlier!

After using the factor for rho the calculation ran a lot more timesteps, but there seems still to be an open issue...it still becomes unstable.

By the way, do you know the default value, when I use no detailed specification for rho-underrelaxatrion, is it 1?

Regards
Uli
uli_u is offline   Reply With Quote

Old   October 6, 2005, 16:15
Default Hi Uli, I did not converge
  #11
Super Moderator
 
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,416
Rep Power: 15
mattijs is on a distinguished road
Hi Uli,

I did not converge it fully but it seemed to work with a really low underrelax for k,eps,rho (say 0.05)

Might just be that I haven't run it enough though.
mattijs is offline   Reply With Quote

Old   October 9, 2005, 15:16
Default Hi Mattijs, thanks for this
  #12
New Member
 
Ulrich Uphoff
Join Date: Mar 2009
Posts: 9
Rep Power: 7
uli_u is on a distinguished road
Hi Mattijs,

thanks for this information. I tried it and the job ran for a long time without getting unstable. I also stopped it, there was no real convergence. I think the problem itself is not a good example, I will think about a better one, maybe using a hex grid.

Nevertheless I still have the feeling that there is something wrong with the turbulence BC - especially epsilon. In several calculations I experienced that using "zeroGradient" works much better than putting a fixed value of epsilon on the inlet. I will investigate this in more detail and collect some pictures showing this behaviour.

Regards
Uli
uli_u is offline   Reply With Quote

Old   May 29, 2007, 13:33
Default Hi all, can anyone send me
  #13
New Member
 
Giovanni Boldrini
Join Date: Mar 2009
Location: Bologna, Italy
Posts: 10
Rep Power: 7
giovanni is on a distinguished road
Hi all,

can anyone send me Ulrich's test case for rhoSimpleFoam?
The one mentioned on Monday, October 03, 2005 - 04:51 am?

Thanks a lot in advance!

Giovanni
giovanni is offline   Reply With Quote

Old   July 11, 2007, 06:47
Default Hi all, I would like to tak
  #14
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 9
braennstroem is on a distinguished road
Hi all,

I would like to take a look at the test case, too! Is it possible to get a small piece, without the mesh!?

Regards!
Fabian
braennstroem is offline   Reply With Quote

Old   December 15, 2007, 14:38
Default hi could somebody email me
  #15
New Member
 
Laurence Griffiths
Join Date: Mar 2009
Location: Bristol, UK
Posts: 18
Rep Power: 7
lgriffiths is on a distinguished road
hi

could somebody email me either the above rhoSimpleFoam test case, or just any test case (for rhoSimpleFoam).

mesh is not important.

this would be a huge help, and much appreciated!

cheers,
Laurence
lgriffiths is offline   Reply With Quote

Old   February 10, 2009, 16:24
Default Are there any test cases kicki
  #16
New Member
 
John Paul Handrigan
Join Date: Mar 2009
Location: Ottawa, Ontario, Canada
Posts: 16
Rep Power: 7
jphandrigan is on a distinguished road
Are there any test cases kicking around for rhoSimpleFoam? If there are, I'd greatly appreciate it if someone could it to my email address at jhand085@uottawa.ca . Thank you in advance!
jphandrigan is offline   Reply With Quote

Old   March 13, 2009, 12:30
Default Hello Everyone, Even I am i
  #17
Senior Member
 
Rishi .
Join Date: Mar 2009
Posts: 138
Rep Power: 7
hellorishi is on a distinguished road
Hello Everyone,

Even I am in the same boat...
There is no tutorial for rhoSimpleFoam in 1.5 or 1.5.x and I would like to have an example to understand the working BC,system, constant etc.

If anyone has a please help.

THanks
RIshi
hellorishi is offline   Reply With Quote

Old   March 15, 2009, 01:09
Default Rishi, Drop me an email at kc
  #18
New Member
 
Kirk Jarvis
Join Date: Mar 2009
Posts: 6
Rep Power: 7
kcjarvis56 is on a distinguished road
Rishi,
Drop me an email at kcjarvis56 at hotmail(dot)com and I will send you a case.
Kirk
kcjarvis56 is offline   Reply With Quote

Old   March 17, 2009, 12:50
Default
  #19
Senior Member
 
Rishi .
Join Date: Mar 2009
Posts: 138
Rep Power: 7
hellorishi is on a distinguished road
Thanks Kirk,

The case is now converging !
hellorishi is offline   Reply With Quote

Old   April 2, 2009, 17:43
Default
  #20
Member
 
Mihir
Join Date: Mar 2009
Posts: 40
Rep Power: 7
mihir1310 is on a distinguished road
hello

may i have the test case for rhoSimpleFoam ??




thanx & regards !!!!!!!!!
mihir1310 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
RhoSimpleFoam maritozzo OpenFOAM Running, Solving & CFD 1 April 30, 2010 19:18
RhoSimpleFoam jphandrigan OpenFOAM Running, Solving & CFD 18 March 29, 2009 12:05
RhoPorousSimpleFoam RhoSimpleFoam spv24 OpenFOAM Running, Solving & CFD 4 November 12, 2008 10:19
Problem with rhoSimpleFoam matteo_gautero OpenFOAM Running, Solving & CFD 0 February 28, 2008 07:51
RhoSimpleFoam luca OpenFOAM Running, Solving & CFD 0 August 22, 2005 13:26


All times are GMT -4. The time now is 03:11.