Question

When is Leibniz rule applicable to control volume?

(a) When control volume is moving

(b) When control volume is deforming

(c) When control volume is fixed

(d) In all conditions

I have been asked this question during an online interview.

I need to ask this question from Governing Equations topic in section Governing Equations of Fluid Dynamics of Computational Fluid Dynamics

Answer 1

The correct answer is (c) When control volume is fixed

To explain: Leibniz rule is applicable to a system only if a system variable is independent. When control volume is fixed, position of the control volume becomes independent. So, Leibniz rule is applicable only to fixed control volumes.