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Uros January 25, 2007 06:44

2D Simulations
Hallo everybody!

Does anyone know how to create a 2D (quasi) simulation in CFX10? The help file says it's possible, but following those steps I always get a message: "CFX can only operate on Solid Volumes!". I want to create a simple planar rectangular surface with one moving boundary, no inlets and outlets and simulate gas behaviour bounded by the geometry.

Thanks a lot for any replies! Greetings,


Joe January 25, 2007 07:47

Re: 2D Simulations
Use the forum search function.

Santiago Orrego. January 25, 2007 17:27

Re: 2D Simulations
You have to extrude, 1 cell deep, in your mesh software.

tarek January 26, 2007 08:07

Re: 2D Simulations
You need to create a volume, to simulate 2D simulation, so u have to choose one unite in the Z direction, and ur reall values in the (x,y) direction. Tarek

Deepak Narayan Ramanath January 27, 2007 05:30

Re: 2D Simulations
Basically, you have to know that CFX is a 3-D solver and not a 2-D, therefore, you need to have a 3-D mesh for CFX. For simulating 2-D, extrude the mesh (one cell thick) in the Z direction. Or if you are trying to do a 2-D axisymmetry, then extrude by rotation by say 1 degree or max 5-degree, depending on the complexity of the model. Since you would be having a slip-wall boundary condition on those extruded symmetry faces, the fluxes calculated are equated to 0. This acts as symmetry BC.

Robin January 29, 2007 14:36

Re: 2D Simulations
Don't use a free slip wall, use Symmetry or, if there is swirl, create a Periodic interface.


Bak_Flow January 29, 2007 21:22

Re: 2D Simulations
Why not Robin....?



Robin February 24, 2007 09:04

Re: 2D Simulations
Hi Bak_Flow,

There is a subtle difference in the discretization at the wall. A free slip wall will not enforce a zero gradient, whereas a symmetry plane will. How the solver does this also affects the calculation of gradients which are used for second order terms. To make a long story short, if you have a grid one element thick and use a free slip wall the advection term will only be first order upwind. So use symmetry.

Regards, Robin

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