Particle motions in sheared suspensions XX: Circular cylinders

The behavior of rigid circular cylinders suspended vertically in viscous fluids in laminar shear flow was found to compare favorably with a theory for infinitely long cylinders which we have extended to include interactions between two cylinders of different diameters. A description of the versatile Couette apparatus in which most of the experiments were performed is included. Observations were made on single cylinders at various distances from the wall bounding flow, on collisions between cylinders of both equal and unequal diameters and on interactions between a cylinder and a sphere. Collision doublets were found to be either permanent or separating, depending on the initial orientations and separations of the particles. The behavior of these particles is analogous to that of spheres in Couette flow. On a trouve que le comportement de cylindrea circulaires et rigides en suspension verticale dans des fluides visqueux, dans un ecoulement laminaire a cisaillement, se comparaǐt favorablement avec les donnees ďune theorie relative aux cylindres infiniment longs qui, par extension s'appliquent aussi aux reactions entre deux parametres de diametres differents.On decrit ľappareil versatile Couette, lequel a servi a la plupart des experiences. On a fait des observations sur des cylindres simples a diverses distances de ľecoulement voisin de la paroi, sur des collisions entre cylindres de diametres egaux et inegaux et sur les reactions entre un cylindre et une sphere. On a trouve que les “doublets” de collision etaient soit permanents ou tendaient a se separer, selon ľorientation initiale des particules. Le comportement de ces particules est analogue a celui des spheres dans ľecoulement Couette.