Abstract
In the classical analyses of both Brownian (perikinetic) and velocity gradient (orthokinetic) flocculation by Smoluchowski1, particle encounters in sufficiently dilute systems are treated as binary collisions between rigid spheres. In these analyses it is assumed that the relative motions between particle pairs can be described by superposition of the isolated particle motions, each particle behaving as though the others were not present. With this assumption the only permitted interactions are those of the external force fields resulting from combined attraction and repulsion. According to the far-reaching DLVO theory, the field forces are a consequence of London-van der Waals attraction and electrical double layer repulsion2.
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Abbreviations
- a:
-
particle radius
m
- A:
-
Hamaker constant
J
- A(s), B(s), C(s):
-
hydrodynamic functions
dimensionless
- B(v, v):
-
breakup function
m3 s-1
- C:
-
floc breakup coefficient
- CA :
-
attraction group
dimensionless
- CR :
-
repulsion group
dimensionless
- ds :
-
maximum stable diameter
m
- D:
-
absolute isolated particle diffusivity
m2s-1
- Di :
-
absolute diffusivity of particle i
m2s-1
- D12 :
-
relative diffusivity between unequal particles
m2s-1
- Dr :
-
relative diffusivity between equal particles
m2s-1
- D:
-
relative diffusivity tensor
m2s-1
- Fe :
-
external field force
N
- f(p):
-
electromagnetic retardation function
dimensionless
- G:
-
velocity gradient
s-1
- h:
-
gap between particles
m
- I:
-
rate of encounters with reference particle
s-1
- k:
-
Bolzmann’s constant
J °K-1
- K:
-
coefficient in Eq (33)
m3
- KB :
-
floc breakup rate coefficient
- ℓ:
-
exponent in Eq (31)
- m:
-
exponent in Eq (32)
- ni :
-
number concentration of particle i
m-3
- n(v):
-
number concentration distribution
m-6
- N:
-
total number concentration
m-3
- N12 :
-
binary encounter frequency per unit volume
s-1 m-3
- P:
-
parameter in Eq (14)
- P:
-
Pressure
N m-2
- r:
-
radial separation
m
- R11 :
-
velocity correlation function
dimensionless
- s:
-
dimensionless radial separation
dimensionless
- T:
-
temperature
°K
- → ur :
-
relative velocity vector
ms-1
- ui :
-
Cartesian velocity component
m s-1
- u′i :
-
turbulent velocity fluctuation
m s-1
- ui :
-
mean velocity
m s-1
- v:
-
floc volume
m3
- V:
-
interaction potential energy
J
- xi :
-
Cartesian coordinate
m
- αo :
-
orthokinetic aggregation efficiency
dimensionless
- αp :
-
perikinetic aggregation efficiency
dimensionless
- α f p :
-
Fuchs’ perikinetic aggregation efficiency
dimensionless
- β(v, v):
-
binary aggregation coefficient
m3 s-1
- ε:
-
energy dissipation rate per unit mass
J s -1 kg-1
- εf :
-
fluid dielectric coefficient
NV-2
- η:
-
turbulence length microscale
m
- κ:
-
reciprocal Debye length
m-1
- λ:
-
wavelength for dispersion force
dimensionless
- μ:
-
absolute viscosity
kg m-1 s-1
- ν:
-
kinematic viscosity
m2 s-1
- ρ:
-
fluid density
kg m-3
- ι:
-
Debye length group
dimensionless
- φ:
-
total suspended volume concentration
dimensionless
- ψ0 :
-
potential at onset of diffuse double layer
V
- ω:
-
rotor angular velocity
s-1
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Spielman, L.A. (1978). Hydrodynamic Aspects of Flocculation. In: Ives, K.J. (eds) The Scientific Basis of Flocculation. NATO Advanced Study Institutes Series, vol 27. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-9938-1_4
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DOI: https://doi.org/10.1007/978-94-009-9938-1_4
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