- **FLUENT**
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- - **1.#qnb**
(*https://www.cfd-online.com/Forums/fluent/76997-1-qnb.html*)

1.#qnbHello,
when I run my program, it stops at 3 iterations and on Fluent I can read "solution is converged" and I have 1.#QNBe+00 that appears... Does anyone know why? I replace my real by float but it doesn't change the result. |

HiHey, I am getting the same problem with 1.#qnb. I was wondering how did u replace your real by float?
Thanks |

i had the same problemthe problem i solved was a very simple: axissymmetric (horizontal) channel. I set up a axis BC at the upper boundary of my channel and get this error:
iter continuity x-velocity y-velocity time/iter ! 1 solution is converged 1 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 0:00:12 999 when i change: the upper boundary set a Wall BC, and the bottom set the Axis BC all fixed and a solution was gone..:) I've heard before that Axis BC must be only horizontal...it seems that this boundary must be also a lower boundary...in my simple geometry at least)))) hope that it will be helpful...to someone..))) |

For those who were directed to this forum by google searching for "QNBe":
1.#QNBe+00 is what Fluent shows when it really does not know what to do, for example when somewhere in the calculation there was a 0/0. In floating point operations, 0/0 results in NAN (Not Any Number). In Fluent, this is #QNAN. Fluent wants to represent this in exponential notation: 1.#QNANe+00 The next thing that happens is that Fluent wants to represent is with 4 digits. N is bigger than 5, so the A is rounded up to B, and it becomes 1.#QNBe+00 If you see this, it means that something in the calculation went wrong. It can have many, many different causes. |

In this specific case, people really should have read the manual.
It clearly states that the axis of symmetry in an axisymmetric simulation has to coincide with the x-axis. |

Hello,
In my case, #QNB is coming after around 3500 iterations. So how can I know what is going wrong? |

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