A beaker contains water up to a certain height as shown. If water is allowed to get discharged through a small diffuser, what type of flow will it be in pipe?

The velocity in which the water is discharged with a velocity

With time as the water gets discharged,v decreases as H decreases. Hence, it will be an unsteady flow.
According to the continuity equation, ?AV =constant, where ?= density, A= cross-sectional area of flow, V = velocity of flow. In this case, water is treated as an incompressible liquid (? =constant) but the nozzle has a gradually increasing diameter (A increases). At a given instant, V at the exit of the nozzle will be less than that at it?s entrance. Hence, it will be a non-uniform flow.