# 2D axisymmetric simulation

Member

I am trying to do a 2D axisymmetric simulation in ANSYS Fluent. In the geometry cell I deselected solid bodies and line bodies so that only the surface is imported and changed the analysis type to 2D. In the mesh cell I changed the geometry 2D behavior to axisymmetric. I also created a named section for the centerline which will be the axis. Finally, in the setup cell, under boundary condition tab, I made the centerline type axis. I also went to the general tab to change the setting from planar to axisymmetric.

Despite all the changes I made, the simulation doesn't work when I run a calculation. I keep getting floating point errors. Note that the simulation works for a full 2D model when I don't make the axisymmetric changes.

• Member
edited February 2019
• Start over with a fresh Fluent analysis block.
• Pick the Geometry tab and set the Analysis Type to 2D before you start.
• Create a surface on the XY plane and the axis must be the X-axis and the surface must be on the +Y side of the X-axis.
• In Meshing, add the named selections and set the 2D behavior to Axisymmetric under the Geometry Details window.
• In Workbench, Update the Mesh cell to get a green check, then Refresh the Setup cell then double click to start Fluent
• In Fluent, you will be able to set the model to Axisymmetric.

• Member
edited February 2019

I think this worked! Before I had a fluid going from the inlet to the outlet (origin centered at 0,0 and then fluid goes positive y-direction with gravity going down y-direction), now the fluid velocity would be dependent on the x-direction correct?

• Member
edited February 2019

If it's a vertical pipe in the real world, you still have to draw it on the X-axis for it to be Axisymmetric, that's just the way the software was written. You can turn on Gravity, it just has the acceleration component in the X direction so X is up and down, while Y is the radial dimension and the software is computing a full 360 degrees of volume of fluid by analyzing that radial slice.