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Old   March 18, 2005, 07:01
Default Iterations
  #1
Ant
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I'm using STAR CD version 3.24. If I set the number of iterations at 1000000 or more,

? FORTRAN Runtime Error: ? Illegal character in numeric imput ? READ(UNIT=10,...

I don't need 1000000 iterations, it was just a large number to ensure that it wouldn't stop before meeting the residual conditions, but I wasted a lot of time figuring out that this was the problem rather than the rest of my setup. AFAIK there is no error message other than the above.

Has anyone else had this problem? Is there a way to ensure it doesn't happen?
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Old   March 18, 2005, 16:59
Default Re: Iterations
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CPF
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The easy solution is don't set the number of iterations to 1000000. If you look at the problem file you'll see that where the iteration number is, there is just *********.

As a rule of thumb, think about what you are doing, and don't enter stupid numbers into CFD codes.

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Old   March 19, 2005, 06:33
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Ant
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Of course I realise not to use 1000000, but this is not the point. THe only stupidity on my part was not checking the problem file. But there is nothing wrong with entering an arbitrarily large number to ensure that it will not stop unless it has converged. My point was only to note that the message STAR gives you is not easy to relate to the cause.

And perhaps since I've only been using STAR since January, there is a possibility I might enter stupid numbers from time to time..... we all start somewhere
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Old   March 21, 2005, 14:10
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steve
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You didn't make a stupid mistake and in fact the error message didn't even come from STAR - it came from the OS or more probably the run-time component of the compiler as it tried to read an invalid field. In a perfect world, when you entered the number, pro-STAR should have prevented you from entering something that big if it couldn't write it out. On the other hand, any given analysis requires thousands of numbers to be entered and checked for sanity and occasionally one slips by the checks because the programmer never considered the possibility or for some other disconnect. You got caught in an unlucky combination. If you report it to the support people it should get fixed so it doesn't happen to you or the next guy again.
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Old   March 21, 2005, 17:46
Default Re: Iterations
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Ant
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That's a good idea, thanks, I'l do that
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Old   March 24, 2005, 17:30
Default Re: Iterations
  #6
CPF
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Not sure I agree. There is everything wrong with entering arbirtraily large numbers, especially in a Fortran program. Even Excel will throw a wobbler if you overflow it.

Part of being a good CFD engineer is not leaving these things to chance. Every value you enter should be considered.

Bad workmen don't blame their tools
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Old   March 25, 2005, 14:50
Default Re: Iterations
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Ant
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"Bad workmen don't blame their tools"

Whom do they blame then?

Well, I admit it was a bad idea and it was my mistake, but I don't think it would be unreasonable for it to be documented for the beginners, or at least throw up an error message that can be connected.. but this is perhaps an obvious point for somebody with experience and there are probably other things they need to work on.

Thanks for making me think about the problem a bit more though

Ant
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