YOU KNOW YOUR DISCRETIZATION IS APPROPRIATE WHEN:

THE ANSWER REMAINS THE SAME FOR:

SMALLER TIME STEPS,

AND

SMALLER CELL SIZES

It is very easy to specify more and smaller time steps, so time step size can be readily evaluated.

Unless you have an automated grid generator / input file creator, then the time requirements and logistics of rebuilding the model with smaller cell sizes renders the task unreasonable. One of the GUI's we will explore, GMs builds a conceptual model using GIs concepts. This is the only tool I know of allows you to rapidly and painlessly experiment with grid size.

Without such a tool, it is important that you push yourself to use smaller grid sizes from the beginning of numerical model development because you will never be able to test this issue.