what is the difference between 2D and axisymmetric

April 3, 2006, 11:00

Can sombody explain what is the difference between 2d and axisymmetric.

Let us say I am modelling a channel I and I am 2D simulation that is a plne in xy axis and now let us say the problem is smmtric over x axis then I must simulate chennel with 2d and symmetric boundary condition.

Now consider I am simulating a flow in cyleinder and and let us say flow is axissymmetrical and since I am simulating in 2d axis I can assume it as 2d and do the simulation.

I just want to know what is wrong in my interpretation.

Q

April 4, 2006, 03:37

when you are using a axis, fluent calculates the "volume" of the domain rotating the 2D plane AROUND the axis. The means, if you have a axis-symmetric pipe flow (a cylinder) you take the centre line as middle axis and 1/2 cross-section as simulation domain.

The symmetry option is used, when you have a symmetry plane (or line in 2D). e.g.: a square, that can be divided into two symmetrical domains. In 2D does that mean, that Fluent will calculate the "volume" with the reference lenght.

By the way: Fluent does not accept the BC axis, when the domain is set to symmetry or it does not accept the BC symmetry when it is set to axis-symmetric.

April 3, 2006, 11:00	what is the difference between 2D and axisymmetric	#1
Q Guest Posts: n/a	Can sombody explain what is the difference between 2d and axisymmetric. Let us say I am modelling a channel I and I am 2D simulation that is a plne in xy axis and now let us say the problem is smmtric over x axis then I must simulate chennel with 2d and symmetric boundary condition. Now consider I am simulating a flow in cyleinder and and let us say flow is axissymmetrical and since I am simulating in 2d axis I can assume it as 2d and do the simulation. I just want to know what is wrong in my interpretation. Q

April 4, 2006, 03:37	Re: what is the difference between 2D and axisymme	#2
Ralf Schmidt Guest Posts: n/a	when you are using a axis, fluent calculates the "volume" of the domain rotating the 2D plane AROUND the axis. The means, if you have a axis-symmetric pipe flow (a cylinder) you take the centre line as middle axis and 1/2 cross-section as simulation domain. The symmetry option is used, when you have a symmetry plane (or line in 2D). e.g.: a square, that can be divided into two symmetrical domains. In 2D does that mean, that Fluent will calculate the "volume" with the reference lenght. By the way: Fluent does not accept the BC axis, when the domain is set to symmetry or it does not accept the BC symmetry when it is set to axis-symmetric.