Update fvm_classes.py

[Fratorhe]

• Bug fix on line 238
• removed unnecessary computation of d since it is computed inside the loop
• added timestep in the d computation line 410

Thanks for this code, very educational!

[danieljfarrell]

Thanks for the fixes. This reminds me that I need to rebuild the documentation site, it does not render mathjax any more. I had one questions, added to the review.

[Fratorhe]

Thanks to you, I found it very useful! I converted it to python 3 and I will eventually push it in my fork. I'll keep you posted.

[danieljfarrell]

Ok that's great,I will merge that in when you are done.

[Fratorhe]

Have a look at my update. I did not update your examples, but I added new ones. I compared my examples with analytical solutions as well, so it should be fine. Give it a try to see if it works well for you.