[mb.pejvak]

Hi everyone;
I plan to apply FAS multigrid method in my code but I have some problem in understanding:

first of all, I can not understand what "relaxation" means? infact, I suspect this step used only for solving L*U=F that F and U find from restriction or prolongation steps or it is used in calculating NS equation with initial value that is obtained from these two steps?

and second, is it necessary to calculate L (coefficient matrix) in each step of relaxation? as it is known L is depends on U and V (Velocity) and with changing u and v it will change.

and finally, what should be done for pressure? is it necessary to all three step of multigrid are applied for pressure? I ask it because in convergence, only for u and v is considered.

thanks in advance