Preventing infinite fields?

mosquera · June 17, 2013, 10:43

Greetings all,

I'm working on a foam project in which I need to define a new field based on several other parameters (k, e, nut).

I've done this so far using something of the form

volScalarField B ("B", 2*k/(nut*e))

My problem is that there are points in my field inw hcih either nut or e are equal to zero. Therefore, the code compiles but upon running it in my case I receive a core dump. I assume this is due to the computer running out of memory.

What's a good workaround such that I can bound B between, say, 0 and 1 regardless of nut and e?

I've tried to use if-then statements but unfortunately c++ is new to me and I haven't eben able to get good results.

Thanks,

Matt

mturcios777 · June 17, 2013, 12:58

Foam has a built in quantity called SMALL that can be added to the denominator that is very near machine zero, but still strictly non-zero. This won't prevent huge values but will keep you from getting NAN errors, and help you track down errors.

mosquera · June 18, 2013, 04:56

That was helpful, thanks!

It's running now but I'm still looking for a way to bound the values.

June 17, 2013, 10:43	Preventing infinite fields?	#1
mosquera New Member Matt Mosquera Join Date: Jun 2013 Location: Lewisburg, PA Posts: 18 Rep Power: 12	Greetings all, I'm working on a foam project in which I need to define a new field based on several other parameters (k, e, nut). I've done this so far using something of the form volScalarField B ("B", 2k/(nute)) My problem is that there are points in my field inw hcih either nut or e are equal to zero. Therefore, the code compiles but upon running it in my case I receive a core dump. I assume this is due to the computer running out of memory. What's a good workaround such that I can bound B between, say, 0 and 1 regardless of nut and e? I've tried to use if-then statements but unfortunately c++ is new to me and I haven't eben able to get good results. Thanks, Matt

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June 17, 2013, 12:58		#2
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	Foam has a built in quantity called SMALL that can be added to the denominator that is very near machine zero, but still strictly non-zero. This won't prevent huge values but will keep you from getting NAN errors, and help you track down errors.

June 18, 2013, 04:56		#3
mosquera New Member Matt Mosquera Join Date: Jun 2013 Location: Lewisburg, PA Posts: 18 Rep Power: 12	That was helpful, thanks! It's running now but I'm still looking for a way to bound the values.