17.1.1. Simplifications and Assumptions

Try these first

1. 1.

   What is the Mach number threshold for assuming incompressible flow?

   Hint

   Remember the conditions under which flow becomes incompressible.

2. 2.

   Define control volume.

   Hint

   Think about where you would set boundaries in flow problems.

3. 3.

   Under what Mach number is the flow generally considered incompressible?

   • <0.3
   • >0.3
   • =0.5

   Hint

   Think about the balance of flow properties.

4. 4.

   True or False: Incompressible flow means that the density of the fluid changes regardless of the flow conditions.

   • True
   • False

   Hint

   Reflect on the definition of incompressibility.

5. 5.

   A fluid with a Mach number of 0.15 is flowing in a horizontal pipe. Describe how you would analyze the flow in terms of the simplifications discussed and derive the relevant equations.

   Hint

   Refer to the definitions of incompressible flow.

6. 6.

   If a pipe has a varying diameter, explain how you would approach calculating mass flow rate with respect to the assumptions laid out about incompressibility.

   Hint

   Think about how area affects velocity in comparison with density.