KR342: I'm using the Monte Carlo radiation model in ANSYS-CFX. The run crashes at the first radiation call with the following message. How do we fix this?
ERROR #666000005 has occurred in subroutine WALK.
Too many iterations while using Monte Carlo.
This may possible be due to:
1 - Highly reflective walls
2 - Small absorption coefficient
3 - Symmetry planes are too close, i.e. 2D geometry
4 - Geometry specification error
For Highly Specular Boundaries (Diffuse Fraction = 0) and for 2D geometries with a nearly transparent media (absorption coefficient close to 0) , the radiation solver stops when there are infinite reflections and reports that there are `too many iterations while using Monte Carlo". Possible ways to fix this include:
(A) INCREASE THE MAXIMUM NUMBER OF HISTORIES:
This will allow rays to be tracked for longer. To increase the maximum number of histories, you should right click on your domain in the CFX-Pre Outline tree, select 'Edit in Command Editor' and add the line shown below:
THERMAL RADIATION MODEL:
Maximum Number of Histories = 200e6 -------------> Add this line (The default value is 2e6)
Number of Histories = 1000000
Option = Monte Carlo
Then press 'Process'. (Alternatively add it to the CCL using 'cfx5cmds' from the command line if you are more familiar with this)
(B) Widen the 2D geometry so that the symmetry planes are further apart.