# Floating Point Error for Mixing Plane Model

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 October 2, 2003, 22:43 Floating Point Error for Mixing Plane Model #1 Lee Guest   Posts: n/a Sponsored Links Hi, I am doing some turbomachinery simulation with Mixing Plane Model. Anyone know the reason why I have the floating point error after few iteration? I already lower the under-relaxation value and changed geometry couple of time. Thanks!

 October 3, 2003, 08:57 Re: Floating Point Error for Mixing Plane Model #2 thomas Guest   Posts: n/a Hello. If you are using a UDF check if you do not have a division by 0. Thomas

 October 3, 2003, 10:16 Re: Floating Point Error for Mixing Plane Model #3 Lee Guest   Posts: n/a Hi, Thomas, Thanks for reply. I could not really understand. Would you mind to explain to me in detail how to check where the problem is? Thanks again.

 October 3, 2003, 10:27 Re: Floating Point Error for Mixing Plane Model #4 thomas Guest   Posts: n/a Well I am assuming you are using a UDF. What I mean is really often when people creates UDF they generally forget that for the first iteration some variable can be zero. Therefore if you are divided a number by zero your solver will blow up telling you 'non floating error'. 'non' means 'not a number'. Depending on your UDF this kind of error does not effectively happens at the first iteration. An example, if you are simulated a domaoin with a stagnant water as initial condition and you are calculated for the first iteration something like 1/Re therefore lets call it BOOM !!! because Re=0 . To find this kind of think there a simple way : reread your UDF. All that is just a suggestion, it might that or something else I do not figure out yet. cheers thomas

 October 6, 2003, 09:27 Re: Floating Point Error for Mixing Plane Model #5 Andy Guest   Posts: n/a I've had similar problems recently with floating point errors on a multi processor simulation of something fairly complex, but with no UDF's, just a mixing plane alone. The solution for my problem seems to be to run on a single processor, where it runs fine....? Any and all suggestions gratefully received!

 October 6, 2003, 18:38 Re: Floating Point Error for Mixing Plane Model #6 Lee Guest   Posts: n/a Thanks, I am not using UDF.

 October 7, 2003, 04:29 Re: Floating Point Error for Mixing Plane Model #7 thomas Guest   Posts: n/a Hey, I remember one day I got that case because I have made a mistake in boundary conditions. I mean in my case I had set a wall boundary condition instead of an axis boundary condition and then FLuent refuses to calculate telling me 'floating point error'. Maybe it could help you. thomas

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