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Floating Point Error for Mixing Plane Model

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Old   October 2, 2003, 22:43
Default Floating Point Error for Mixing Plane Model
  #1
Lee
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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!
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Old   October 3, 2003, 08:57
Default Re: Floating Point Error for Mixing Plane Model
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thomas
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Hello. If you are using a UDF check if you do not have a division by 0. Thomas
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Old   October 3, 2003, 10:16
Default Re: Floating Point Error for Mixing Plane Model
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Lee
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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.
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Old   October 3, 2003, 10:27
Default Re: Floating Point Error for Mixing Plane Model
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thomas
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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
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Old   October 6, 2003, 09:27
Default Re: Floating Point Error for Mixing Plane Model
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Andy
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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!
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Old   October 6, 2003, 18:38
Default Re: Floating Point Error for Mixing Plane Model
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Lee
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Thanks,

I am not using UDF.
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Old   October 7, 2003, 04:29
Default Re: Floating Point Error for Mixing Plane Model
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thomas
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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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