Numerical Essential #1:Boundary

Last time when I mentioned whether my solution is stable or not, it all pointed to one thing->boundary condition. Yes, I did look into my supervisor code and in my mind, I was looking at the same thing i.e his BC and mine is the same. Perhaps, one thing that I couldn't get rid of since my undergrad (or perhaps childhood) is that I tend to think differently when I looked at something and this seems badly influence my coding ability. Anyhow, put this aside first and and I want to say about boundary condition.

My supervisor asked if I did my BC correctly and I confidently replied yes, and we checked together. Of course, I made some precipitate mistakes and when that was fixed, everything goes as expected. In this case, I have 3 types of BC: a)outlet b)fixed c)hard. These are just an extension of Dirichlet BC. An outlet BC is where the ghost cell is the same as the neighboring cell; either left or right depending on the location, a fixed BC is when we fixed the ghost cell value and hard BC is like having a wave hitting a hard wall and reflected.  

All I'm saying is that, boundary and a correct one is crucial and those who said there is no boundary  or no limit (in life too) are actually just a bunch of dunderheads who will screw up later.