
[Sponsors] 
May 2, 2005, 03:04 
I want to solve the NavierSto

#1 
New Member
Amalia Apalategui
Join Date: Mar 2009
Posts: 13
Rep Power: 10 
I want to solve the NavierStokes 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 

May 2, 2005, 03:10 
That's correct.
The viscosi

#2 
Senior Member
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,793
Rep Power: 23 
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 

May 2, 2005, 05:20 
I have run icoFoam and one get

#3 
New Member
Amalia Apalategui
Join Date: Mar 2009
Posts: 13
Rep Power: 10 
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 

May 2, 2005, 05:25 
Have you tried with a smaller

#4 
Senior Member
Join Date: Mar 2009
Posts: 854
Rep Power: 15 
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.


May 13, 2005, 10:36 
hello,
I want to couple the

#5 
Guest
Posts: n/a

hello,
I want to couple the equation of energy and the equations of NavieStokes 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(TTref). T: is has temperature do you have an idea to add this term in the velocity equation on Z direction? thank's 

May 13, 2005, 11:34 
Hi chafi fatima zohra,
I wo

#6 
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. 

May 13, 2005, 12:07 
Hi chafi fatima zohra,
me a

#7 
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 

June 14, 2005, 08:22 
hi chafi fatima zohra,
i wa

#8 
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? 

August 10, 2005, 10:28 
Hi,
I was trying to modify

#9 
New Member
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 10 
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. 

August 10, 2005, 18:09 
You might want to have a look

#10 
Super Moderator
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,416
Rep Power: 18 
You might want to have a look at the postProcessing/stressComponents utility to find out about the coding.


August 11, 2005, 06:29 
Thanks for the information. I

#11 
New Member
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 10 
Thanks for the information. I will try to do that.


August 15, 2005, 07:23 
Hi,
Still stack with solver

#12 
New Member
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 10 
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. 

August 15, 2005, 13:52 
Hi,
forget about my earlier

#13 
New Member
Kanyanta Valentine
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 11
Rep Power: 10 
Hi,
forget about my earlier message. I have managed around that problem. best regards. 

May 27, 2012, 16:13 
phi term in icoFoam

#14 
New Member
Aurelien
Join Date: Jan 2012
Posts: 7
Rep Power: 7 
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)); 

May 28, 2012, 02:30 

#15 
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,910
Rep Power: 28 
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() ); Best,
__________________
Alberto Passalacqua GeekoCFD  A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM  An opensource implementation of quadraturebased moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. 

May 28, 2012, 08:30 

#16 
New Member
Aurelien
Join Date: Jan 2012
Posts: 7
Rep Power: 7 
Alright, thank you!
I checked the compressible cases, and that all makes sense now. 

Thread Tools  
Display Modes  


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 