Motion of an array of drops through a cylindrical tube

摘要: We study the pressure-driven transient motion of a periodic file deformable liquid drops through cylindrical tube with circular cross-section, at vanishing Reynolds number. The investigations are based on numerical solutions equations Stokes flow obtained by boundary-integral method. It is assumed that viscosity and density equal to those suspending fluid, interfaces have constant tension. mathematical formulation uses Green's function in domain bounded externally tube, which computed tabulation interpolation. surface each drop discretized into quadratic triangular elements form an unstructured interfacial grid, tangential velocity grid-points adjusted so mesh remains regular for extended but limited period time. results illustrate nature deformation, thereby extend previous studies axisymmetric small-drop small-deformation theories. found when capillary number sufficiently small, start deforming from spherical shape, then reach slowly evolving quasi-steady shapes. In all cases, migrate radially toward centreline after initial rapid deformation. apparent suspension expressed terms effective pressure gradient necessary drive rate. For fixed separation, non-axisymmetric be higher than file. case motion, reaches minimum certain ratio separation radius. Drops large radii radius ratios develop slipper shapes, similar red blood cells capillaries, only numbers excess critical value.