Once Upon a Time...
..when working in Zambia I observed a cubic mass of consolidated material, about 30 tonnes, resting in the roof trusses in the TORCO plant. It had been left there because it was in a disused building and the folk thereabouts needed the bin steel for another job. The block had been there for over 10 years, undisturbed. Moisture content played its part of course, but the location, high in the building in the tropics, did not help either. I guess there was a baking effect which took place over a relatively short time. This probably caked over the walls and the outlet and then the whole block became free to solidify. I doubt anybody went aloft to examine if the internals were solid.
As Lyle and Lyn imply there are several factors involved. If a bin is ever used the underlying implication is that material is going to become stationary regardless of the desired flow conditions. Stationary material ignores the flow conditions: it is not flowing. As Lyn says ".. it's a question of looking at the possible mechanisms appropriate to the material, its condition and ambient influences." Those questions can be very difficult to answer.
I have a second generation question. Has discrete element analysis reached the stage were it can WARN about the onset of INDISCRETION: ie. is there a limiting case available already or is there still a long way to go. Would it be worth finding out?
John Gateley
johngateley@hotmail.com
www.the-credible-bulk.com