I am working with a transient analysis that I would like to stop automatically when I reach a certain gas concentration in a tank. The tank is a box with a circular inlet on the top at one end, and a rectangular outlet on the top at the other end. The circular inlet is a simple Inlet Volume Flow, and the rectangular outlet is set to Environmental Pressure. I have a volume goal for the tank airspace defined, and I have tried messing with equation goals to tell the solver when to finish the calculation. Does anyone know of a slick way to make this happen? Is it even possible? I'm working with an initial gas concentration of 100 ppm, and I would like the solver to stop when that concentration drops below 10 ppm. I tried the following:

1. Set up equation goal = 11 - {VG Max Volume Fraction of Gas}

2. Set calculation control options to use equation goal for convergence, then set criteria to 1 ppm

I am not sure this will do what I really want though, since the delta between iterations could be < 1 ppm even when the maximum concentration is > 10 ppm. I'm basically trying to prevent the solver from running any longer than necessary. Any ideas?

- Dan

negative. was looking for something similar for an aero problem. best case for your automation would be to set a reasonable length for solving and then output something if it doesn't meet criteria and allow for a restart with longer time.