Drag interaction effects in linear sphere-assemblies

Free-fall terminal velocities of single spheres and of single-row assemblies containing up to six spheres, with line of centres of spheres perpendicular to the direction of motion, have been determined in the particle Reynolds numbers range 0.2-4, and interaction effects obtained in the case of assemblies relative to drag on single isolated spheres, are discussed. The observed decrease in the drag on a sphere of an assembly is explained on the basis of theoretical considerations governing flow phenomena in such systems.