The flow patterns in three symmetric and two asymmetric louver-walled
granular moving bed systems are studied experimentally. The flow patte
rn histories of granular solids in moving beds were recorded by video
camera throughout the whole test period. The image processing system i
ncluding a frame grabber was used. Selected discrete images showing th
e flow pattern development were digitized and stored in files. Individ
ual granular flow frames show a development of quasi-stagnant tones cl
ose to the louvered walls, the shear zones and a central flow region w
ith width depending on the louver angle. The vertical shift of one or
the other louvered wall in asymmetric configuration considerably influ
ences the history of quasi-stagnant zones.