# Does the 3D STL file matter as long as the cross section is the same in 2D?

Hi Guys,

This is kind of a weird question. I have been working on 2D simulations on Project Chrono for a while now.

Currently, I am working with a 2D simulation of a cylinder (in 3D). As you know, any side cross section of a cylinder is a rectangle. So, for the sake of simplicity, I created a STL file of a rectangle with sides equal to the diameter and height of my cylinder.

In 2D simulations, I have been trying to simulate free decay tests and the results are not as expected. So, I was wondering if my 3D STL file had any effect on the 2D simulation?

## Comments

If you want to create a rectangale... you can just use drawbox...

In any case, plot the particles generated in 2D (Case_All.vtk) to understand what are you running.

For decay tests you should use:

1) floating object filled of particles (using autofill for the STL)

2) use laminar+SPS

Regards