- **Main CFD Forum**
(*https://www.cfd-online.com/Forums/main/*)

- - **singularity in axis-symmetric probelm
**
(*https://www.cfd-online.com/Forums/main/4854-singularity-axis-symmetric-probelm.html*)

singularity in axis-symmetric probelm
Does anyone know how to treat the singularity due to (1/r) in an axis-symmetric problem?
In stream-function vorticity method for 2D axis-symmetric problem: Ur=(1/r)ds/dz Uz=-(1/r)ds/dr when r->0 both->infinite. If the mesh size becomes small, it is very hard to get a solution unless you use very very small timestep. Thanks a lot. |

Re: singularity in axis-symmetric probelm
Unless I'm overlooking something (always a possibility), the radial velocity (Ur) has to be zero at r = 0 unless a mass source or sink exists at r = 0.
Also, at r = 0 d(Uz)/dr = 0; the Uz velocity must be symmetric about r = 0. This also says that the stream function is a constant (a streamline!) at r = 0. These two can be combined to give a boundary condition for the vorticity at r = 0. |

All times are GMT -4. The time now is 14:40. |