I've researched the "rules" regarding use of tenses in scientific writing. However, I'm still not sure how to describe the simulations I've done during my thesis.
Just a simple example:
1: An example model was developed to simulate the behavior during compression.
Here I'm describing something I did in the past, similar to an experiment, hence I'm using the past tense.
Then I'll describe what happens during the simulation, or how specific properties of the simulation model were set.
2: The piston geometry is imported as a .stl-mesh. By moving the mesh in direction of the negative z-axis, the particles in the cylinder are compressed until...
I'm not sure about the tenses used in example 2. I could have also written:
3: The piston geometry was imported as a .stl-mesh. By moving the mesh in direction of the negative z-axis, the particles in the cylinder were compressed until...
I can't decide whether example 2 or 3 is the better choice.