# 5.3.1: Non Deformable Control Volume

- Page ID
- 700

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When the control volume is fixed with time, the derivative in equation (??) can enter the integral since the boundaries are fixed in time and hence,

Continuity with Fixed b.c.

\[

\label{mass:eq:intSrho}

\int_{V_{c.v.}} \dfrac{d\,\rho}{dt} dV = -\int_{S_{c.v.}} \rho\,U_{rn} \, dA \tag{12}

\]

Equation (??) is simpler than equation (??).

### Contributors

Dr. Genick Bar-Meir. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or later or Potto license.