Geldart particle classification

The behavior of solids fluidized by gases can be classified into four groups using the density difference and mean particle diameter. This particle classification was introduced by D. Geldart in 1973.

Source code

chemics.geldart.geldart_chart(dp, rhog, rhos, dpmin=None, dpmax=None)[source]

Creata a Matplotlib figure of the Geldart chart 1. Data points for drawing the demarcation lines and regions were digitized from Figure 2 in 2.

  • dp (float) – Sauter mean particle diameter [µm]

  • rhog (float) – Gas density [g/cm³]

  • rhos (float) – Particle density [g/cm³]

  • dpmin (float, optional) – Minimum particle size from particle size distribution [µm]

  • dpmax (float, optional) – Max particle size from particle size distribution [µm]


Matplotlib figure.


Particle diameter must be in microns (µm) and density in g/cm³.


For a single particle size

>>> geldart_figure(300, 0.1, 2.5)

For a particle size with min and max sizes

>>> geldart_figure(300, 0.1, 2.5, 100, 500)



D. Geldart. Types of gas fluidization. Powder Technology, 7, pp. 285-292, 1973.


H.A. Khawaja. Review of the phenomenon of fluidization and its numerical modelling techniques. The International Journal of Multiphysics, vol. 9, no. 4, pp. 397-407, 2015.