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.
Fail to find convergence when scaling down radiation problem
Posted 21 oct. 2010, 04:27 UTC−4 1 Reply
Please login with a confirmed email address before reporting spam
Hi !
I'm trying to compute how the temperature changes around a particle "hanging" in air using the HT with "Surface to surface" radiation and Transient solution.
The outer surface of the biggest circle is given a BC og 20 degC and the particles initial temperature is 5000 degC
The model works nicely when using a circle 2 cm of silica glass in diameter (best fit material in database), surrounded by a 20 cm circle of air.
When scaling the model down it crashes imidiately giving the following message for the time dependent solver:
Failed to find consistent initial values.
Last time step is not converged.
Changing the particle temperature to 1000 degC gives a solution, so I'm thinking this has to do with some scaling issue.
Have been reading a lot of posts here on the forum and tried suggestions given there, but still I get a failure.
I'm new to COMSOL so I was hoping some of you experienced users could provide me with some tips and tricks to get a solution.
Sorry for the long post - thanks alot for your help
Nils Eivind
I'm trying to compute how the temperature changes around a particle "hanging" in air using the HT with "Surface to surface" radiation and Transient solution.
The outer surface of the biggest circle is given a BC og 20 degC and the particles initial temperature is 5000 degC
The model works nicely when using a circle 2 cm of silica glass in diameter (best fit material in database), surrounded by a 20 cm circle of air.
When scaling the model down it crashes imidiately giving the following message for the time dependent solver:
Failed to find consistent initial values.
Last time step is not converged.
Changing the particle temperature to 1000 degC gives a solution, so I'm thinking this has to do with some scaling issue.
Have been reading a lot of posts here on the forum and tried suggestions given there, but still I get a failure.
I'm new to COMSOL so I was hoping some of you experienced users could provide me with some tips and tricks to get a solution.
Sorry for the long post - thanks alot for your help
Nils Eivind
1 Reply Last Post 21 oct. 2010, 05:42 UTC−4
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
If you have a non linear problem (and radiation exchange is rather of that kind) it's often usefull to get to your point by a parametric sweep to ramp gently your temperature or whatever variable to the final value
--
Lykke til
Ivar
If you have a non linear problem (and radiation exchange is rather of that kind) it's often usefull to get to your point by a parametric sweep to ramp gently your temperature or whatever variable to the final value
--
Lykke til
Ivar