Solution:
In Unit Operation, some devices are mentioned, for instance, Venturi meter.
\begin{parts}
\part [4] Please describe briefly what’s the purpose of a Venturi meter
\part [4] and what is the correlation used for this device. (no need to write down the correlation equation!!)
\part [6] It can be correlated to the concept of Thermodynamics of flow processes. In the following, there are four equations, please choose those equation(s) that could be related to the concept of Venturi meter.
\end{parts}
\begin{align*}
\frac{dP}{dx} & = – \frac{T}{V} \cdot \left( \frac{1 + \beta u^2 / C_p}{1 – M^2} \right) \cdot \frac{dS}{dx} \quad & (1) & \quad\quad\quad\; & u \frac{du}{dx} & = T \cdot \left( \frac{\beta u^2 / C_p + M^2}{1 – M^2} \right) \cdot \frac{dS}{dx} \quad & (2)\\
\frac{dP}{dx} & = \frac{u^2}{V A} \cdot \left( \frac{1}{1 – M^2} \right) \cdot \frac{dA}{dx} \quad & (3) & \quad\quad\quad\; & \frac{du}{dx} & = – \frac{u^2}{A} \cdot \left( \frac{1}{1 – M^2} \right) \cdot \frac{dA}{dx} \quad & (4)\\
\end{align*}
