Boundary condition and initial condition

In CFD,boundary condition and initialization are an important part.The role of boundary condition is how our fluid domain is going to simulated for the given condition.In terms of partial differential equation,based on our boundary condition what necessary terms are to be calculated.By default the continuity and momentum will b calculated,but if we switch on the energy equation then only the temperature variable in the energy equation is taken into consideration.As far as initialization is concerned,it is like given an reference value in our cell zone or at the center of the cell to be precise so that our system will get an head start for getting a converged solution faster.The two types of initialization are standard initialization and hybrid initialization,where former is used to give initial value from a particular region of interest wrt to the boundary condition inputted and the former is based upon the a specific set of pre iterations calculated by using the laplace equation where important parameters are computed and inputted.