Rheologica Acta

, Volume 8, Issue 4, pp 448–456 | Cite as

Flow of granular solids through horizontal orifices

  • M. Ahmad
  • N. Pilpel


A study has been made of the flow of materials which differ considerably in their physical properties in the size range 0.005 to about 0.150 cm. They include glass beads, lactose, carboxymethylcellulose, magnesia and sand.

Employing a term for particle shape, an equation has been developed which enables the flow rates to be predicted with an accuracy of about ± 7%. This is
$$\begin{gathered} D_0 = (3.24 + 1.50D_p - 0.57f) \hfill \\ \times \left( {\frac{{4w}}{{60\pi \varrho \sqrt g }}} \right)^{\frac{1}{{4.23 + 0.58\log D_p - 0.22f}}} cm, \hfill \\ \end{gathered} $$
whereD0 is the orifice diameter in cm,Dp the particle diameter in cm.ϱ the particle density in g/ml,w the flow rate in g/min,g is 981 cm sec−2 andf is a shape factor.


Polymer Magnesia Lactose Size Range Particle Diameter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Diameter of orifice cm


Diameter of particle cm


Diameter of tube cm


“Shape” coefficient


“Shape” coefficient


Head of material in tube cm


A function of particle properties


A function of particle properties


Flow rate g/min


“Shape” factor


Particle density g/ml


Acceleration due to gravity cm/sec2


Length of particles cm


Breadth of particle cm


Thickness of particle cm


Elongation ratio


Flatness ratio.


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Copyright information

© Dr. Dietrich Steinkopff Verlag 1969

Authors and Affiliations

  • M. Ahmad
    • 1
  • N. Pilpel
    • 1
  1. 1.Department of Pharmacy, Chelsea College of ScienceUniversity of LondonEngland

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