Flowability, also known as powder flow is a property that defines an ability of a powdered material to flow, related to cohesion.
[1] Powder flowability depends on many traits:[1][2] ISO 4490:2018 norm (and its precedent, ISO 4490:2014) standardizes a method for determining the flow rate of metallic powders.
It uses a normalized/calibrated funnel, named Hall flowmeter.
[3]