sonicFoam: simulation "stuck" without error

Lena_K · April 13, 2015, 05:10

Hello!

Sorry for disturbing, i am not familiar with OpenFOAM, but currently i need to simulate the density distribution inside the gas target (i'm using sonicFoam because of high speed and kOmegaSST model because of high pressure gradient). I've wrote geometry in blockMeshDict, and it seems to be ok, and there's no error when i'm running the simulation. But the problem is that final density distribution (after there's almost no changes in distributions at different timesteps) does not looks reasonable.
I've tried different pressure for the inlets (i've changed time step respectively), and simulation "stuck" at different stage. I would be very grateful for any help.

Regards,
Lena

Lena_K · April 17, 2015, 05:56

Looks like problem is lying under proper mesh. I'm getting very high courant number for big timesteps, therefore i reduce the timestep up to 10^-11 s and i got reasonable max courant number, but very small mean courant number. Could that cause a problem?

Lena_K · May 12, 2015, 10:04

I was running a 3D simulation with timestep of 10^-9 s at fine mesh, and it does not reach steady state, therefore i build 2D model and test it with the same timestep. Simulation has been running for two weeks with more progress, than 3D simulation, but the fluctuations in the resulting fields are very big, i guess due to high pressure (for low pressures and therefore bigger timesteps it works good). Therefore i have a problem: to avoid the fluctuation i need do increase time step, this lead to higher Courant number -> simulation crash. What can i do to solve this problem?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Problem running perturbUCyl	sen.1986	OpenFOAM	17	June 4, 2019 05:56
Errors in UDF	shashank312	Fluent UDF and Scheme Programming	6	May 30, 2013 20:30
Compile problem	ivanyao	OpenFOAM Running, Solving & CFD	1	October 12, 2012 09:31
OpenFOAM on MinGW crosscompiler hosted on Linux	allenzhao	OpenFOAM Installation	127	January 30, 2009 19:08
error while compiling the USER Sub routine	CFD user	CFX	3	November 25, 2002 15:16

April 17, 2015, 05:56		#2
Lena_K New Member Join Date: Apr 2015 Posts: 4 Rep Power: 11	Looks like problem is lying under proper mesh. I'm getting very high courant number for big timesteps, therefore i reduce the timestep up to 10^-11 s and i got reasonable max courant number, but very small mean courant number. Could that cause a problem?

May 12, 2015, 10:04		#3
Lena_K New Member Join Date: Apr 2015 Posts: 4 Rep Power: 11	I was running a 3D simulation with timestep of 10^-9 s at fine mesh, and it does not reach steady state, therefore i build 2D model and test it with the same timestep. Simulation has been running for two weeks with more progress, than 3D simulation, but the fluctuations in the resulting fields are very big, i guess due to high pressure (for low pressures and therefore bigger timesteps it works good). Therefore i have a problem: to avoid the fluctuation i need do increase time step, this lead to higher Courant number -> simulation crash. What can i do to solve this problem?