[Hywoo]

Hello,

I am currently analyzing 2D axisymmetric cases, such as pipe flow and the flow around a 2D axisymmetric sphere.

I would like to gain a deeper understanding of how OpenFOAM handles axisymmetric cases, particularly with respect to the governing equations. For instance, in Hoffman Vol. 1, when converting Cartesian coordinates to axisymmetric coordinates, the governing equations introduce an additional source term. like this, I want to know OpenFoam how to handle axisymmetric analysis in terms of governing equation (how to construct new source term)

+ If you could point me toward any relevant references or codes, I would greatly appreciate it.

Thank you very much

Hywoo

[Tobermory]

There is no change to the solver equations. Axisymmetric conditions are imposed in OpenFOAM as a boundary condition on the flow - refer to https://doc.cfd.direct/notes/cfd-gen...edge-condition for more details.

[Hywoo]

Thanks for your reply.

I would like to confirm if I have understood correctly:

1. Since OpenFOAM solves problems in Cartesian coordinates rather than cylindrical coordinates, the governing equations do not change even when solving an axisymmetric case.

2. The difference between 2D planar flow(on xy plane) and 2D axisymmetric flow(Axis is x-dir) is that for axisymmetric cases, the calculation includes the z-axis direction, and, as mentioned in the URL you provided, boundary value and boundary gradient conditions are added for the wedge.

If there is anything incorrect in my understanding, I would appreciate your clarification.

Thanks
Hywoo

[Tobermory]

yes, that looks right to me.

[Hywoo]

Thank you very much