Module 9: Packed beds
  Lecture 29: Drag, particles settling
 
 

Drag: We have already introduced this term in the previous lecture. There are two types of drag: form drag and wall or shear drag. The former is because of the fluid–pressure on the solid–surface and acts perpendicular to the surface wall. Drag is because of shear–forces and acts parallel to the surface.

 

 
(Fig. 29b)
  • A horizontal plate parallel to fluid flow will experience drag only because of wall shear.

form drag
wall drag
  
  (already defined in previous lectures)
  (Stoke’s Law for Rep < 1)