# 2D Simulations

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 January 25, 2007, 06:44 2D Simulations #1 Uros Guest   Posts: n/a Sponsored Links 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, Uros.

 January 25, 2007, 07:47 Re: 2D Simulations #2 Joe Guest   Posts: n/a Use the forum search function.

 January 25, 2007, 17:27 Re: 2D Simulations #3 Santiago Orrego. Guest   Posts: n/a You have to extrude, 1 cell deep, in your mesh software.

 January 26, 2007, 08:07 Re: 2D Simulations #4 tarek Guest   Posts: n/a 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

 January 27, 2007, 05:30 Re: 2D Simulations #5 Deepak Narayan Ramanath Guest   Posts: n/a 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.

 January 29, 2007, 14:36 Re: 2D Simulations #6 Robin Guest   Posts: n/a Don't use a free slip wall, use Symmetry or, if there is swirl, create a Periodic interface. -Robin

 January 29, 2007, 21:22 Re: 2D Simulations #7 Bak_Flow Guest   Posts: n/a Why not Robin....? Regards, Bak_Flow

 February 24, 2007, 09:04 Re: 2D Simulations #8 Robin Guest   Posts: n/a 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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