# How to use axisymmetric model?

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 August 29, 2004, 15:57 How to use axisymmetric model? #1 Jeffery Guest   Posts: n/a I am modelling a simple case(a jet in a cylinder.) In order to save some time, I choose axisymmetric model in solver. But it doesn't work until I change it to 2d model. Is there anybody can tell me what happen here?( In boundary condition, I set one side as axis. ) Another question: In my opinion, if I set boundary as axis, it should be axisymmetric model.Why should I choose it again in solver? Is there any contradict?

 August 30, 2004, 03:21 Re: How to use axisymmetric model? #2 Bikash Guest   Posts: n/a hi you got to choose axisymmetry,to differentiate between symmetric and axisymmetric model. Axisymmetric model will have to sweep 360 degrees.

 August 30, 2004, 03:49 Re: How to use axisymmetric model? #3 HVN Guest   Posts: n/a Your axis must be 0x.

 August 30, 2004, 08:29 Re: How to use axisymmetric model? #4 Mahesh Masurkar Guest   Posts: n/a hi axisymetry will work for 2d only. you can't set axisymmetry for 3d. that to in 2d ,plane should be xy-plane and axis of symmetry should be x-axis. Shoonya likes this.

 August 30, 2004, 11:25 Re: How to use axisymmetric model? #5 Jeffery Guest   Posts: n/a Thanks, I changed my model according to your suggestion, and it works

 August 30, 2004, 11:34 Re: How to use axisymmetric model? #6 Chief Guest   Posts: n/a I too am using an axisymmetric mesh and it seems to work fine BUT when activated as axisymmetric, if I then do a "grid check" it says FAILED as "invalid axisymmetric grid-there are 290 nodes below the x-axis" If I switch back to 2D only grid check is fine. I have orientated x-axis as rotational axis and set BC accordingly. What, if anything, have I done wrong? Chief

 August 30, 2004, 15:55 Re: How to obtain mean flow #7 Lee Guest   Posts: n/a hi, I am modeling packed bed column. I would like to know that I can I obtain/extract mean flowrate for the selected region in the packed bed reactor? Thanks Lee

 August 31, 2004, 01:59 Re: How to use axisymmetric model? #8 Mahesh Masurkar Guest   Posts: n/a hi There shd not be any element below X-axis for axisymmetric problem. Try to change the geometry in gambit and orient in XY plane, do meshing & then import the mesh in Fluent with Axisymmetric. Mahesh

 August 31, 2004, 10:04 Re: How to use axisymmetric model? #9 Chief Guest   Posts: n/a Mahesh, thanks. I have a correct grid and mesh when 2D option is selected. A grid check passes fine. When the axis of rotation (also the x axis) is defined as an axis BC and the axisymmetric model is selected the grid check then fails. It is as if when the grid is rotated around the central axis it counts the nodes which have been swept around as being below the x axis. Well of course they would be because they have been swept around 360 degrees! Perhaps it is just a software glitch. The simulation seems to run fine anyway but I do not have the confidence to ignore the error message. I know that the bouyancy model I am using is very unstable and I am just trying to cover any possible areas of ambiguity. cheers Chief

 September 1, 2004, 18:45 Re: How to use axisymmetric model? #10 amir Guest   Posts: n/a when you have axisymmetric shape you must modeling only one half of the problem then define-->models --> solve --> axisymmetric then other condition and iterate

 September 2, 2004, 08:42 Re: How to use axisymmetric model? #11 Mahesh Masurkar Guest   Posts: n/a 1)For axisymmetrical cases, the mesh must lie in the +y half of the plane. Fluent will use the x-axis as the axis of rotation. Any portions of cells falling below the x-axis will result in negative volumes.

 September 2, 2004, 11:19 Re: How to use axisymmetric model? #12 Chief Guest   Posts: n/a ok cheers Chief

 July 30, 2011, 07:46 #13 New Member   soroush.armd@yahoo.com Join Date: Jul 2011 Posts: 5 Rep Power: 14 hi,i want to model a rotational disk,which one should i choose?axisymmetric or axisymmetric swirl?(i don't have a swirling flow!) in addition,we could assign rotational speed to walls in both models,what is the difference between them? tnx.

 August 1, 2011, 09:20 #14 Member   JP Join Date: Mar 2009 Posts: 57 Rep Power: 18 Axisymmetric model is used when the geometry is axisymmetric (for example, flow through a pipe, where you can model just a 2D half-section of the pipe). Here, there is no flow in the z-axis. In axisymmetric swirl, there is swirling flow in the z-axis (normal to the geometry plane). In your case, you can model it like a stirred tank, by giving a rotational velocity to the walls.

 August 2, 2011, 05:23 #15 New Member   soroush.armd@yahoo.com Join Date: Jul 2011 Posts: 5 Rep Power: 14 Thank you for your reply I am trying to model a flow on a rotating disk,so I have a velocity component normal to the plane,you mean that I should use axisymmetric swirl model? tnx! Last edited by soroush; August 5, 2011 at 18:53.

 June 4, 2016, 01:07 Reference values for axisymmetric model #16 New Member   Sabarish Narayan Join Date: May 2016 Posts: 5 Rep Power: 10 Hi I am modelling flow past a bullet which is an axisymmetric model. But the Cd value i am getting does not match with the experimental values. how do i set the reference area for getting the correct value of Cd?

 July 7, 2016, 10:35 #17 New Member   Join Date: May 2016 Posts: 2 Rep Power: 0 Hello, Jeffery I also have the same problem with you (mesh cheking problem for axisymmetric model). I think you should translate the mesh so that all the nodes are above the rotational axis, here the x-axis. Otherwise, there can be some calculation mistakes. For details please read ANSYS user's guide Chapt. Translating the mesh. Best regards.

 July 8, 2016, 08:12 2D axisymmetric #18 New Member   Join Date: Jul 2016 Posts: 4 Rep Power: 10 Hi, I would like to ask if it is possible to view the results of a simulation using a 2D axisymmetric model in 3D?

July 9, 2016, 18:49
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Quote:
 Originally Posted by ShimiSan Hi, I would like to ask if it is possible to view the results of a simulation using a 2D axisymmetric model in 3D?
I don not think so. The axisymmetric model is only available in 2d simulations.

 July 11, 2016, 04:22 Thank you huanxiongkuai #20 New Member   Join Date: Jul 2016 Posts: 4 Rep Power: 10 Thank you huanxiongkuai I don not think so. The axisymmetric model is only available in 2d simulations.[/QUOTE]