My Hopper Design Cliff Notes provide a nice summary of flow property test methods and bin design. When I give workshops, I provide these notes along with a spreadsheet that performs the calculations.
Caking and its Prevention is the non-copyright version of an article that I wrote for Chemical Engineering magazine.
Optimization of Pharmaceutical Formulations for Flow shows how Jenike's flowability coefficient FFC can be misinterpreted. It's better to measure the flow properties of a powder over a range of consolidation pressures so that critical hopper outlet dimensions and hopper angles can be calculated.
I periodically add other documents on powder handling and processing. Be sure to visit and check for updates.