Particle Technology

Dilute systems - sedimentation

Problems 5.7

Question 1.i
The settling velocity of small particles may be reliably obtained from Stokes's law. Larger particles, however, do not obey Stokes's law. Alternative correlations between drag coefficient and Particle Reynolds number do exist - but the settling velocity is a constituent of the Particle Reynolds number hence the answer needs to be known before the appropriate equation to use can be identified! To overcome this problem Heywood published a set of tables that can be used over a wide range of settling velocities and particle sizes. The first step in using the tables is to calculate two functions P and Q

A solid and liquid has a specific gravities of 2.8 and 1.0, respectively and the liquid viscosity is 0.001 Pa s, the value of the function P is 2.87x10⁴ m^-1, the equations for function P and function Q are:
Heywood Tables parameter P

	a) 2.87x10^-2 b) 2.87x10⁴ c) 2.87 d) 0.490
Note, specific gravity is the same as relative density (relative to water).