Thursday September 18, 2014 at 12:45pm
When solving a cfd project, Flow Simulation provides very useful convergence information. The user's understanding of convergence can be enhanced if the convergence symbols and interval are switched on and their meaning understood. This blog explains how to do this and what the symbols mean.
When a Flow project is solving, SOLIDWORKS pops up the 'Solver' window that informs users of progress. Flow users will be familiar with this as it allows you to see in numerical, graphical and pictorial form what is happening as the solution progresses and the goals converge.
However, many users will be unaware that whilst this is happening you can modify the viewing options to show the 'Convergence history' and the 'Analysis interval'.
The 'Convergence history' inserts a green circle onto the goal graph line to show visually at what iteration the goal was achieved. If at a later iteration the goal diverges then it will place a red circle at that point. See the illustration below ...
The 'Analysis interval' is the range of iterations that is being used to measure if convergence is being achieved. In the example above the goals are being checked for convergence between the 41st iteration and the 61st iteration. The interval is shown with a rectangle placed on the 'Iterations' axis. During these iterations Flow is checking to see if the goal 'Current value' is within the goal 'Criterion'. If it is consistently within the criterion, then the goal is considered to have converged and the green circle is placed on the goal plot line.
The goal 'Criterion' (i.e. tolerance on the result) is, by default, set automatically but can be manually set by the user if desired.
How is this enabled? The answer is to right mouse button click on the Goal Plot and the window below pops up. The convergence symbols are enabled by selecting the 'Show convergence history' and the interval is enabled by the 'Show analysis interval' button.
Other tools in the window control the scaling of the X axis (very useful if you have a lot of iterations as you can scale them to fit within the window) and the units it uses.
by Andy Fulcher
Solid Solutions Management Ltd