Dear all I am the new user on Fluent program. I have a question about the effect of node size on the reliable of the simulation results, why the smaller give more reliable than the larger size. Can I find the simulation time from the simulation result file.

Thank in advance Worakij

I guess you mean Cell Size (Not node size) if that is correct, then you can start by searching the Wiki or your Numerical analysis book

You need to figure out the meaning of convergence. According to it, as the del_x and del_t is smaller, the numerical solution become close to the exact solution. Thus, when the cell size or mesh size is relatively smaller, the solution seems close to the exact solution or goes to more accurate solution.