# Boundary conditions - OpenFoam

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 February 25, 2010, 14:01 Boundary conditions - OpenFoam #1 New Member   sankarv Join Date: Feb 2010 Posts: 26 Rep Power: 9 Sponsored Links I am a new user of OpenFoam and I am trying to set-up an under-expanded supersonic jet issuing into an open atmosphere. I am using the rhoCentralFoam and it has an example for the a similar jet. Even though I can just copy the b.c. files (p,T and U) from the tutorial, I would like to better understand the various keywords in these files. For example, Jet_inlet { type totalPressure; value uniform 300000.0; p0 uniform 300000.0; U U; phi phi; rho none; psi psi; gamma 1.4; } I do not understand all the keywords here. what does p0, phi, and psi stand for ? I saw another example where all of the above keywords are not used ? Is there any documentation for what kind of keywords must be specified for what kind of boundary conditions ? Somebody please help. Thanks Vaidya

 March 19, 2010, 05:05 #3 New Member   Join Date: Nov 2009 Posts: 2 Rep Power: 0 did you find a solution for the definition of psi, phi and U in totalPressure bc?

April 4, 2010, 18:02
Creating New solver: for particle laden compressible jets
#4
New Member

sankarv
Join Date: Feb 2010
Posts: 26
Rep Power: 9
Hello OpenFoamers

I am a new user of OpenFoam and I am trying to set-up a particle-laden
under-expanded supersonic jet issuing into an open atmosphere.
Note, before I started OpenFoam, I ran fluent and got a converged
solution for this problem

Here are details of OpenFoam simulation:
---------------------------------------
Solver: rhoCentralFoam
Grid: axi-symmetric grid imported from Fluent using fluentMeshtoFoam
I.C: I used the converged Fluent solution as initial condition for openFoam
I managed to get a converged steady state solution for this
problem without particles

!----------------------------------
Now I am trying to run a particle-laden jets. Since the solver
rhoCentralFoam does not have Lagrangian Particle Tracking in it, I realized
that I have to create a new solver.
I came across the icoLagrangianFoam solver which is basically a particle
tracking solver for an incompressible flow.

I found a nice tutorial "Tutorial icoLagrangianFoam/SolidParticle" by
Auerlia Vallier
I used that and managed to implement particle tracking
in the rhoCentralFoam solver.
I called this new solver rhoCentralParticleFoam

This works well. But the problem is that the drag model in the original
icoLagrangianFoam is a very simple constant drag model.
I want to implement the standard drag model which is a function of
particle Reynolds number based on the stokesian drag for spherical particles.

Chapter 5 in the tutorial describes how to implement this drag model.
When I did these changes I get compilation errors that I cannot comprehend. I admit that I don't know c++ and I am not able to figure out the exact problem.

Can someone help me to fix these compilation errors ?
I have attached a tar file which contains the codes I am using for
this solver
Attached Files
 rhoCentralParticleFoam.tar.gz (15.5 KB, 37 views)

 October 22, 2010, 02:58 underexpanded jets #5 New Member   karthick Join Date: Oct 2010 Posts: 3 Rep Power: 8 halo mr. sankarv i am a new user of fluent! from ur post i learnt that u ve successfully simulated underexpanded jets in fluent. presently i am tryng to simulate the same!!! but i don get the results at alll can u just help me with the same!!!! could u say me wat sort of profile ahs to be put and the necessary boundary conditions to be specified in gambit and the NPR values to be put in the fluent!!!! i am desperately in nedd of ur help !!!

October 22, 2010, 09:29
#6
New Member

sankarv
Join Date: Feb 2010
Posts: 26
Rep Power: 9
Karthick

There is a paper by K. Senesh & V.Babu titled Numerical Simulation of Subsonic and supersonic jets, AIAA 2005-3095. In this paper they talk about the models, grids, initial conditions and boundary conditions for fluent. I followed this paper to setup my case in fluent. Please try to look up this paper.

Quote:
 Originally Posted by karthick halo mr. sankarv i am a new user of fluent! from ur post i learnt that u ve successfully simulated underexpanded jets in fluent. presently i am tryng to simulate the same!!! but i don get the results at alll can u just help me with the same!!!! could u say me wat sort of profile ahs to be put and the necessary boundary conditions to be specified in gambit and the NPR values to be put in the fluent!!!! i am desperately in nedd of ur help !!!

 February 14, 2012, 07:18 #7 New Member   edin michael Join Date: Feb 2012 Posts: 1 Rep Power: 0 Hi i am just starting in cfd... and am trying to simulate under-expanded jet using fluent. but my solution is not converging. can you please help me with it.

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