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

Boundary Conditions for Spraysimulation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 21, 2009, 05:20
Default Boundary Conditions for Spraysimulation
  #1
Member
 
Michael
Join Date: Mar 2009
Posts: 48
Rep Power: 8
farbfilm is on a distinguished road
Hi everybody,

I want to simulate a spray that impinge in a free atmosphere (under standard conditions) using dieselFoam! What are the right boundary conditions for that???

I made a simulation with the zeroGradient-condition for all boundaries! But here the calculation stagnates after a certain time! My assumption is, that there is something wrong with the pressure!

The following lines show an extract of the log-file shortly before the caclulation stagnate:
DICPCG: Solving for p, Initial residual = 0.377132, Final residual = 8.36049e-10, No Iterations 43
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.15917e-14, global = -5.01047e-16, cumulative = -2.09692e-12
DICPCG: Solving for p, Initial residual = 0.000416067, Final residual = 6.60735e-10, No Iterations 25
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.008e-14, global = -7.18694e-16, cumulative = -2.09764e-12

Can somebody help me????

Thanks, Michael
farbfilm is offline   Reply With Quote

Old   April 22, 2009, 08:25
Default
  #2
Member
 
Michael
Join Date: Mar 2009
Posts: 48
Rep Power: 8
farbfilm is on a distinguished road
Hi,

I'm still dealing with my problem...

In the meantime I saw in the 'dambreak'-tutorial that there is a boundary for an atmosphere! There the boundary conditions are:

U (velocity)

type pressureInletOutletVelocity;
value uniform (0 0 0);

p (pressure)

type totalPressure;
U U; \\ name of the velocity field
phi phi; \\ name of the volumetric flux field (or for the use of the muss flux field it will be devided by rho)
rho none; \\ name of the density field
psi none; \\ name of the derivative of density with respect to pressure
gamma 1.4; \\ ratio of specific heats
p0 uniform 1e+5; \\ value for totalPressure

(I wrote the explanations behind the quantities just for those people who have the same problem like me: to find out what are the quantities stand for...)

Now, my first questions: Is that kind of boundary condition even suitable for my spraysimulations?? Is it the right choice??

If yes, I guess in the totalPressure-boundary, U and phi have to be "turned on"!
But what about rho and phi (since dieselFoam is a compressible solver one of them should also be "turned on", right?). How do I have to handle these two quantities??

Can somebody please help me???

Thanks, Michael
farbfilm 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
Impinging Jet Boundary Conditions Anindya Main CFD Forum 24 January 11, 2012 14:40
Problems with boundary conditions for a lowRekOmegaSST turbulence model cfdmarkus OpenFOAM Running, Solving & CFD 16 November 14, 2011 05:44
Pressure boundary conditions Lionel S. Main CFD Forum 1 August 24, 2007 18:03
Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 2 July 15, 2005 04:15
periodic boundary conditions Ahmed Abdelwahab FLUENT 4 March 9, 2000 17:36


All times are GMT -4. The time now is 22:50.