Suppose $\Omega$ is a bounded domain in Euclidean space and you can take it as convex as you wish. Is there a good place to look for a bunch of barrier type functions.
In particular I am looking for a bunch of examples so I can try and show a boundary estimate on the gradient of a harmonic function.

I am attempting to come up with some (what I think) are typical ones; but I would prefer to just look in a text book if they have a bunch of standard ones.