3.2. Difference between thermodynamic and mechanical pressure

Try these first

1. 1.

   Define mechanical pressure.

   Hint

   Think about how internal stresses contribute to this definition.

2. 2.

   What does the Stokes Hypothesis state?

   Hint

   Focus on the specific conditions outlined in the hypothesis.

3. 3.

   What is mechanical pressure derived from?

   • A sum of temperatures
   • A sum of normal stresses
   • Ambient pressure changes

   Hint

   Think about the formula for mechanical pressure.

4. 4.

   Incompressible flow means divergence of velocity is:

   • True
   • False

   Hint

   Relate this condition to fluid flows in engineering.

5. 5.

   A fluid flows through a pipe, and you measure τxx = 4 MPa, τyy = 3 MPa, τzz = 2 MPa. Calculate the mechanical pressure and discuss its significance.

   Hint

   Remember to sum the individual stresses before applying the pressure formula.

6. 6.

   Explain how the Stokes Hypothesis could simplify calculations in hydraulic engineering under certain fluid conditions.

   Hint

   Reflect on scenarios in typical hydraulic applications where fluid state remains relatively stable.