16.2. Dynamic Similarities and Flow Ratios

Try these first

1. 1.

   Define shear stress in your own words.

   Hint

   Think of how fluids slide over surfaces.

2. 2.

   What is the purpose of the Reynolds number?

   Hint

   Recall its significance in flow characterization.

3. 3.

   What does the Reynolds number indicate in fluid flow?

   • It determines drag force.
   • It predicts flow type.
   • It measures pressure.

   Hint

   Relate it back to flow characteristics.

4. 4.

   True or False: Viscosity decreases with increasing temperature.

   • True
   • False

   Hint

   Think about how heat affects fluids.

5. 5.

   A model yacht in a wind tunnel has a drag coefficient of 0.4, frontal area of 0.5 m², and experiences a wind speed of 15 m/s. Calculate the drag force. Consider air density as 1.225 kg/m³.

   Hint

   Use the drag force formula and substitute the values carefully.

6. 6.

   For a sphere with a diameter of 0.5 m in a laminar flow at 1 m/s and a density of 900 kg/m³, calculate the Reynolds number given the dynamic viscosity of 0.001 Pa·s.

   Hint

   Ensure you've made a proper unit conversion to maintain consistency!