Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Error-Failed to find consistent initial values
Posted 24 déc. 2010, 09:37 UTC−5 Computational Fluid Dynamics (CFD) Version 3.5a 1 Reply
Please login with a confirmed email address before reporting spam
Hi everyone,
I have a cylindrical 3D geometry with inflow boundary condition of 20*sin(w*t) [where w=3.2892 ] and 1e5 Pa pressure as exit boundary condition.I set the subdomain initial pressure to be 1e5 Pa.When I try to run this problem it is displaying the error message-'Failed to find consistent initial values'.To tackle this I tried the following:
1) Prescribed 20m/s as inlet velocity condition with exit pressure=1e5 Pa for a steady case and set this steady
solution as the initial condition for my unsteady problem.
2)As a second step I tried to find out the consistent initial values for the unsteady case by going to 'SOLVER
PARAMETERS-TIME STEPPING-TIME STEPS TAKEN BY SOLVER -INITIALISATION ONLY'(directly going into this
step without doing the first doesn't work out)
After the second step settings when I ran the problem hoping that I will get the consisitent initial values I got he
same error message as earlier.
Also the point to be noted is that by following the above procedure I could solve the same problem with inlet
velocity condition alone changed to 20+20*sin(w*t), other condition remaining the same.
I tried the above problem in 2D axisymmetric.There also it didn't work out.
Can anyone help me regarding how to correct this error..
with thanks and regards,
S.M.Ananth
Happy X-mas
I have a cylindrical 3D geometry with inflow boundary condition of 20*sin(w*t) [where w=3.2892 ] and 1e5 Pa pressure as exit boundary condition.I set the subdomain initial pressure to be 1e5 Pa.When I try to run this problem it is displaying the error message-'Failed to find consistent initial values'.To tackle this I tried the following:
1) Prescribed 20m/s as inlet velocity condition with exit pressure=1e5 Pa for a steady case and set this steady
solution as the initial condition for my unsteady problem.
2)As a second step I tried to find out the consistent initial values for the unsteady case by going to 'SOLVER
PARAMETERS-TIME STEPPING-TIME STEPS TAKEN BY SOLVER -INITIALISATION ONLY'(directly going into this
step without doing the first doesn't work out)
After the second step settings when I ran the problem hoping that I will get the consisitent initial values I got he
same error message as earlier.
Also the point to be noted is that by following the above procedure I could solve the same problem with inlet
velocity condition alone changed to 20+20*sin(w*t), other condition remaining the same.
I tried the above problem in 2D axisymmetric.There also it didn't work out.
Can anyone help me regarding how to correct this error..
with thanks and regards,
S.M.Ananth
Happy X-mas
1 Reply Last Post 25 déc. 2010, 05:12 UTC−5
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
I'm not sure its te reason, but a sinus functions start at t=0 with a rather high derivative (which is - or might be wrongly - estimated and used by the iterative solver). Have you tried to start your function by multiplying it with a small step function to get a smoother start ?
--
Good luck
Ivar
I'm not sure its te reason, but a sinus functions start at t=0 with a rather high derivative (which is - or might be wrongly - estimated and used by the iterative solver). Have you tried to start your function by multiplying it with a small step function to get a smoother start ?
--
Good luck
Ivar