How to model a copper bar pulling out from hot water
 

I am trying to model this process


pull a copper bar from hot water(the same situation as dipping a figur into coffee).unsteady state....want to see the whole process...
the old way that I model it is to divide the boundary condition of the copper bar in to many parts, and for each part when it comes out from the hot water, I modify the boundary condition manually. it costs a lot of time because

1. the surface of the copper must consists of many area, for giving them different boudary condition.
2. have to modify the boundary conditon when each small area come out from the water.

I know it's stupid but now I have no idea how to model this process in a whole continous process. Can you please help me, please give me some hints.