Difference between 2D and 3D !

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 January 25, 2005, 04:59 Difference between 2D and 3D ! #1 Christophe Guest   Posts: n/a Hi everybody ! I would be very pleased if someone could give me information about a "possible mistake" I made in a modelisation. I made a 3D case modeling a combustion in a closed volume. Source is a exit nozzle and boundary condition is "pressure inlet" (I know P, T0 and Pstat). I get the convergence and analyse pressure and temperature fieds on the wall in front of the exit source (3,00 m away). I try to realize an equivalent in 2D with an axisymmetric case. The boundary condition "axis" is along the x-axis. I kept the source data defined for 3d case. I mesh the plane with size-function along x that is to say along the flow. The trouble is that I do not get the same result in pressure and temperature (20% different) and the time the flow impact the wall target is greater in the 2d case (6 ms) than for the 3d (3.5 ms). What could be the matter ? Time-step ? Use of a size function ? I hope this trouble could find a answer... Thanks...

 January 25, 2005, 13:21 Re: Difference between 2D and 3D ! #2 ap Guest   Posts: n/a First of all, try to reproduce the mesh you used in 3D in the Axi case. However, I had similar problems in many cases. Usually a flow is not fully symmetrical, so using the axi solver might not be appropriate. Hi, ap

 January 26, 2005, 04:10 Re: Difference between 2D and 3D ! #3 christophe Guest   Posts: n/a Hi, Thanks for your answer. In fact I am not sure that the size function used in the 2d case is the same than in the 3D. I will check it now. Christophe

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