Question on Pressure and Velocity Fields with SIMPLE algorithm
 

Sorry if this seems like a very dumb or simple question but I'm trying to understand CFD on my own.

Currently I've been skimming through Versteeg and Malalasekera's Introduction to Computational Fluid Dynamics: The Finite Volume Method and in the 6th chapter, concerning calculation of the velocity and pressure fields, I see nothing referring to how a the fields change as time continues. Shouldn't the velocity field move along itself as time passes by? Or am I just not understanding what's happening since I've just skimmed through a bit of this chapter.

Any help would be wonderful.

Philip