Particle-size Distribution - Nomenclature

Nomenclature

ρ_p: Actual particle density (g/cm3)

ρ_g: Gas or sample matrix density (g/cm3)

r2: Least-squares coefficient of determination. The closer this value is to 1.0, the better the data fit to a straight-line.

λ: Gas mean free path (cm)

D₅₀: Mass-median-diameter (MMD). The log-normal distribution mass median diameter. The MMD is considered to be the average particle diameter by mass.

σ_g: Geometric standard deviation. This value is determined mathematically by the equation:

σ_g = D_84.13/D₅₀ = D₅₀/D_15.87

The value of σ_g determines the slope of the least-squares regression curve.

α: Relative standard deviation or degree of polydispersity. This value is also determined mathematically. For values less than 0.1, the particulate sample can be considered to be monodisperse.

α = σ_g/D₅₀

R_e(P) : Particle Reynolds Number. In contrast to the large numerical values noted for flow Reynolds number, particle Reynolds number for fine particles in gaseous mediums is typically less than 0.1.

R_ef : Flow Reynolds number.

K_n: Particle Knudsen number.