Imagine I have a cylindrical pipe closed on both ends with lids. I fill it with sand and compress the sand tightly. Now I hold the cylinder vertically and remove the bottom lid. The sand will counter intuitively not fall off apart from a few loose grains. I understand the reason for this. Essentially the downward gravity force acting on each sand grain is counter balanced by net upward friction force. And the friction force arises due to the contact of each sand particle with it's neighbors.
Now, is there a name for this phenomenon? Or, are there related experiments or applications of this phenomenon?
