Air flow through smooth and rough cracks.

A series of laboratory experiments are described which investigated the effect of surface roughness on the air flow characteristics of simple, straight-through, no-bend cracks with smooth and rough internal surfaces. Thecrack lengths, in the direction of flow, were 50.8mm and 76.2mm. For the rough cracks the roughness was simulated with two different grades of commercially available emery-cloth (grade 60 and 100). The effect of roughness on the reduction of air flowing through a crack is also discussed.