Question

What is the physical statement of mass conservation equation for a finite control volume fixed in space?

(a) Net mass flow through the control surface = constant

(b) Rate of change of mass inside the control volume = constant

(c) Net mass flow through the control surface = Rate of change of mass inside the control volume

(d) Net mass flow through the control surface≠Rate of change of mass inside the control volume

I got this question during an online interview.

This question is from Continuity Equation in portion Governing Equations of Fluid Dynamics of Computational Fluid Dynamics

Answer 1

Correct option is (c) Net mass flow through the control surface = Rate of change of mass inside the control volume

For explanation I would say: Statement of mass conservation equation for a finite control volume fixed in space:

Net mass flow through the control surface is equal to the rate of change of mass inside the control volume.