CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

IcoFoam

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 2, 2005, 03:04
Default I want to solve the Navier-Sto
  #1
aap
New Member
 
Amalia Apalategui
Join Date: Mar 2009
Posts: 13
Rep Power: 8
aap is on a distinguished road
I want to solve the Navier-Stokes eq. for incompressible laminar regime and I have chosen the icoFoam solver. I am surprise that in the transportProperties file, only the viscosity is required, and the density??
Thanks
Amalia
aap is offline   Reply With Quote

Old   May 2, 2005, 03:10
Default That's correct. The viscosi
  #2
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,758
Rep Power: 21
hjasak will become famous soon enough
That's correct.

The viscosity is the kinematic viscosity (equals dynamic viscosity divided by the density); same for the pressure. This way, you only need the viscosity.

Enjoy,

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   May 2, 2005, 05:20
Default I have run icoFoam and one get
  #3
aap
New Member
 
Amalia Apalategui
Join Date: Mar 2009
Posts: 13
Rep Power: 8
aap is on a distinguished road
I have run icoFoam and one gets information about the Max. Courant number in the output. For the first time step is around 1, but for the next time steps becomes larger and larger. What does it mean? Does it mean that the cell size of the mesh and velocities do not match?
Thanks
Amalia
aap is offline   Reply With Quote

Old   May 2, 2005, 05:25
Default Have you tried with a smaller
  #4
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 13
henry is on a distinguished road
Have you tried with a smaller time step? Have you tried running with upwind? It sounds like either your case is not setup correctly or it is unstable with a Courant number as large as 1, you will have to play around to fix it.
henry is offline   Reply With Quote

Old   May 13, 2005, 10:36
Default hello, I want to couple the
  #5
chafi_fatima_zohra
Guest
 
Posts: n/a
hello,
I want to couple the equation of energy and the equations of Navie-Stokes in icoFoam and I want to add the appriximations of Boussinesq only in the direction of Z (push of archiméde).
my problem it is that icoFoam gives the solution of the following equation: UEqu=-grad p and me I want that only in the direction of Z, the component speed (w) must depend on grad p and gB(T-Tref). T: is has temperature
do you have an idea to add this term in the velocity equation on Z direction?

thank's
  Reply With Quote

Old   May 13, 2005, 11:34
Default Hi chafi fatima zohra, I wo
  #6
gellert
Guest
 
Posts: n/a
Hi chafi fatima zohra,

I would recommend to take a look into rhoSimpleFoam, there is in principal
what you want, but restricted to steady state solutions. With help of or some terms
from buoyantFoam one should be able to construct the needed solver.
  Reply With Quote

Old   May 13, 2005, 12:07
Default Hi chafi fatima zohra, me a
  #7
gellert
Guest
 
Posts: n/a
Hi chafi fatima zohra,

me again. Forget my former post. It was wrong, I'm sorry. rhoSimpleFoam is also
for compressible flows.

Marcus
  Reply With Quote

Old   June 14, 2005, 08:22
Default hi chafi fatima zohra, i wa
  #8
chris10
Guest
 
Posts: n/a
hi chafi fatima zohra,

i want to create a new solver for incompressible, laminar flow with boussinesq approximation. so i have combined "icoFoam" and "buoyantFoam". i have compiled my code successfully, but when i want to calculate an example i get the following error:

--> FOAM FATAL ERROR :
request for volScalarField rho from objectRegistry region0 failed
available objects of type volScalarField are

.
Did you have the same mistake? Which models do you use?
  Reply With Quote

Old   August 10, 2005, 10:28
Default Hi, I was trying to modify
  #9
New Member
 
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 8
valentine is on a distinguished road
Hi,

I was trying to modify icoFoam solver to be able to also solve wall shear stresses for flow in pipes (laminar flow ofcourse) but am failing. would you please give me some ideas on building the code and compilation files and run it from FoamX. Please give me an example along side to look at.

Best regards.
valentine is offline   Reply With Quote

Old   August 10, 2005, 18:09
Default You might want to have a look
  #10
Super Moderator
 
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,416
Rep Power: 16
mattijs is on a distinguished road
You might want to have a look at the postProcessing/stressComponents utility to find out about the coding.
mattijs is offline   Reply With Quote

Old   August 11, 2005, 06:29
Default Thanks for the information. I
  #11
New Member
 
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 8
valentine is on a distinguished road
Thanks for the information. I will try to do that.
valentine is offline   Reply With Quote

Old   August 15, 2005, 07:23
Default Hi, Still stack with solver
  #12
New Member
 
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 8
valentine is on a distinguished road
Hi,

Still stack with solver compilation. I was looking at one example on a built configuration file. what does the code

instance "/export/warhol/chris/.foam/apps/FoamX/User/applications/biscuitFoam ";
mean. I was tried to follow the same so I edited it to
"/export/home/valentine/.foam/apps/FoamX/User/applications/wallShearFoam ";

but its still not working. Please help.
valentine is offline   Reply With Quote

Old   August 15, 2005, 13:52
Default Hi, forget about my earlier
  #13
New Member
 
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 8
valentine is on a distinguished road
Hi,

forget about my earlier message. I have managed around that problem.

best regards.
valentine is offline   Reply With Quote

Old   May 27, 2012, 16:13
Default phi term in icoFoam
  #14
New Member
 
Aurelien
Join Date: Jan 2012
Posts: 7
Rep Power: 5
AGIR is on a distinguished road
Hello,

I have a concern regarding the phi term in icoFoam.
I know its definition is: phi=rho*U, rho being the density.
In the icoFoam solver, a simplification is made, as there is no "rho" in the transient term, which makes sense since we consider an incompressible problem.

The problem is that if we make this simplification in a classic momentum equation from Navier Stokes system, there should not be any "rho" in the convective term, but simply "U" (velocity) instead of phi ( div(U, U) ).

My question is: what does OpenFOAM consider in this phi term ?

Here is the momentum equation solved in icoFoam:
Code:
fvVectorMatrix UEqn
(
fvm::ddt(U)                 // transient term
+ fvm::div(phi, U)          // convective term
- fvm::laplacian(nu, U)   // viscosity 
);
solve(UEqn == -fvc::grad(p));
Thanks
AGIR is offline   Reply With Quote

Old   May 28, 2012, 02:30
Default
  #15
Senior Member
 
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,894
Rep Power: 26
alberto will become famous soon enoughalberto will become famous soon enough
Hi,

in incompressible solvers, where the momentum equation is divided by rho (constant), phi is defined as

Code:
surfaceScalarField phi
(
    IOobject
    (
        "phi",
        runTime.timeName(),
        mesh,
        IOobject::READ_IF_PRESENT,
        IOobject::AUTO_WRITE
    ),
    linearInterpolate(U) & mesh.Sf()
);
You can check this in ~/OpenFOAM/OpenFOAM-2.1.x/src/finiteVolume/cfdTools/incompressible/createPhi.H

Best,
__________________
Alberto Passalacqua

GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as live DVD/USB, hard drive image and virtual image.
OpenQBMM - An open-source implementation of quadrature-based moment methods
alberto is offline   Reply With Quote

Old   May 28, 2012, 08:30
Default
  #16
New Member
 
Aurelien
Join Date: Jan 2012
Posts: 7
Rep Power: 5
AGIR is on a distinguished road
Alright, thank you!
I checked the compressible cases, and that all makes sense now.
AGIR 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
Density in icoFoam Densidad en icoFoam manuel OpenFOAM Running, Solving & CFD 8 September 22, 2010 04:10
About phi in icoFoam kar OpenFOAM Running, Solving & CFD 3 February 20, 2008 06:20
Possible bug in icoFoam msrinath80 OpenFOAM Bugs 6 November 19, 2007 18:35
IcoFoam on AIX 53 ds2taieb OpenFOAM Installation 1 March 24, 2006 04:22


All times are GMT -4. The time now is 09:22.