## Friday, May 16, 2008

### Fluent Axisymmetric Simulations

To run an axisymmetric simulation in Fluent you have to do the following

1. In Gambit, make sure your axis of symmetry is aligned with the x-axis (i.e. y = 0)
2. Set the axis edge as an "axis" boundary condition
3. Once you import your mesh into Fluent, set the solver to Axisymmetric

Voila!

Cite as:

1. I am trying to write a guide of definitions of the boundary condition types in Gambit due to the utter lack of such documentation available. Could you possibly provide more insight into how "axis" and "symmetry" boundary conditions differ? In my particular model, I have used a symmetry condition for my axisymmetric model, but am not running an axisymmetric solver in Fluent. Any information you have would be great! Thanks!

2. Hi Aimie. Thank you for your comment.

There's a fundamental difference between the symmetry and axis boundary conditions.

A symmetry BC is used when you have mirror symmetry (could be 2D, or 3D). At a symmetry plane (or line) the normal velocity component is zero, as well as the normal gradients of all variables.

An axis BC is used with axisymmetric simulations only so your model should be 2D (in that case, there are no variations in the tangential direction).

You can refer to sections 6.14 and 6.16 of the fluent documentation.

In your model, assuming it is axisymmteric, you have to change the symmetry BC to axis and use the axisymmetric solver.

3. hi..i am doing Axi symmetric as well as translation periodic B.C problem..

i assigned Axis BC and also periodic B.C in the two edges.. and i exported the x-y msh file to fluent..when i did the import at Fluent its telling me to convert to axisymetric problem even though i assigned Axis BC and i am using windows platform.. when i open a Fluent, i am choosing 2d analysis..

4. Hi Rajavel,

For Fluent versions prior to 6.4:
try "Define->Models->Solver" and choose "Axisymmetric".

I hope that works out for you.

5. Heyz

im a ME student and doing Senior Project. i have a pipe (cylinder) flow and i have to simulate it as 2D axisymmetric Laminar flow. I tried several methods but i am always getting errors.
The last error was "floating point error"

do u know how to solve this error?

if u you dont know, tab could you write the steps that i need to do in gambit and fluent. i will compare it to the steps im using.