notes, may 2024

- rerun the 0.5 mm spacing case when the new thermocouple data arrives
- dt cannot be too big or the numbers go crazy. there is a factor involving
  dx^2 -- ask Wei, or look it up. for now keep dt at 0.05 and it is fine
- plot_profile.py is the old driver, I think simulate.py superseded it but
  the readme still says the old one
