For the continuity equation given by∆ . V̄

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For the continuity equation given by∆ . V̄ = 0 to be valid, where V̄ is the velocity vector, which one of the following is a necessary condition?

1. Steady flow
2. Irrotational flow
3. Inviscid flow
4. Incompressible flow

Correct Option: D

The basic equation of continuity for fluid flow is given by

	ρu		ρv		ρw		ρ
	u		y		z		t

Now if ρ remains constant, then only we can write
∇.v̄ = 0

i.e.	δu	+	δv	+	δw	= 0
	δx		δy		δz

hence incompressible flow