1. Week # 2 MR Chapter 2 Tutorial #2
To be discussed on Jan. 28, 2015.
By either volunteer or class list.
MARTIN RHODES (2008) Introduction to Particle Technology , 2nd Edition. Publisher John Wiley & Son, Chichester, West Sussex, England.

2. Motion of solid particles in a fluid
For a sphere
Stoke’s law

3. Standard drag curve for motion of a sphere in a fluid

4. Reynolds number ranges for single particle drag coefficient correlations
At higher relative velocity, the inertia of fluid begins to dominate.
Four regions are identified: Stoke’s law, intermediate, newton’s law, boundary layer
separation.
Table 2.1 (Schiller and Naumann (1933) : Accuracy around 7%.

5. Single Particle Terminal Velocity

6. Special Cases
Newton’s law region:
Intermediate region:

7. To calculate UT and x (a) To calculate UT, for a given size x,
(b) To calculate size x, for a given UT,
Independent of UT
Independent of size x

8. Particles falling under gravity through a fluid
Method for estimating terminal velocity for a given size of particle and vice versa

9. Non-spherical particles
Drag coefficient CD versus Reynolds number ReP for particles of sphericity ranging from to 1.0

10. Effect of boundaries on terminal velocity
When a particle is falling through a fluid in the presence of a solid boundary the terminal
Velocity reached by the particle is less than that for an infinite fluid.
Following Francis (1933), wall factor ( )
Sand particles falling from rest in air (particle density, 2600 kg/m3)

12. Limiting particle size for Stoke’s law in water

13. Limiting particle size for Stoke’s law in air

14. 850

25. Where the plotted line intersects the standard drag curve for a sphere (y = 1), Rep = 130.
The diameter can be calculated from:
Hence sphere diameter, xv = 619 mm.
For a cube having the same terminal velocity under the
same conditions, the same CD vesus Rep relationship
applies, only the standard drag curve is that for a cube
(y = 0.806)