Flow process:

It is one in which fluid enters the system and leaves it after work interaction, which means that such processes occur in the systems having open boundary permitting mass interaction across the system boundary.

Non flow process:

It is the one in which there is no mass interaction across the system boundaries during the occurrence of process. Different type of non-flow process of perfect gas are given: (1) constant volume process (2) constant pressure process (3) Isothermal process(4) adiabatic process(5) polytropic process

Steady-Flow Process:

It is a process during which a fluid flows through a control volume steadily. That is, the fluid properties can change from point to point within the control volume, but at any fixed point they remain the same during the entire process.