initial value set-up

Hi,


I have a 2D simulation running from T=0 to T=100. First, I run the simulation from T=0 to T= 50. Then I want to use the solution at T=50 plus some value changes in specific domain as the initial value for my simulation from T=50 to T=100.
Can anyone help me out?

Another simple question is: can I find the solution value of variable PIP at T= 50 by PIP(t=50)? if not, how can I reference the variable at specific time point and/or spatial points as well?

Thanks in advance,

John