## General Mechanical

#### Can I use symmetry in my model of thermal analysis

• ansicorp
Subscriber

Hello,

My model is a cylinder, where the load being applied is a laser. I give the load as heat flux and I move the load 360 degrees all around the surface. Is there anyway I can use symmetry in this model? Maybe I can model the outer surface and give the symmetry to the inside cylinder?

Thank you.

• peteroznewman
Subscriber

I imagine you have a tube attached axially to a spindle that spins the tube on its axis. A laser points to the tube axis and shines the spot onto the side of the cylinder, heating the circumference as the tube rotates.

If the period for the laser spot to do one revolution is very short relative to the thermal conductivity of the cylinder material, then the laser spot effectively becomes a "line" heat source on the outer wall.

You can easily use an axisymmetric model of this setup. The requirement is that the axis of rotation of the geometry must be the y axis and the sketch must be in the xy plane. It doesn't matter that the tube may be horizontal in reality, just draw the cross section with the tube vertical on the y axis.

This post has a video on how to do an axisymmetric model for pressure, but the same rules apply for thermal analysis.

You could also put in another plane of symmetry and cut the tube at the plane where the laser hits the wall and just do one end of the tube. If you don't do that, you will want to split the outer edge of the rectangle so you have a vertex to apply the heat from the laser in the middle of the tube length. Note that heat flux can only be applied to a surface area in a 3D model or an edge in a 2D model because it is heat per unit area. If you have a vertex on the edge, you can apply heat to that, not heat flux.