The smooth time-invariant flow that develops when a liquid is moving under conditions in which viscous forces dominate inertial forces. Laminar flow is characterized by a low Reynolds number (see Reynolds number). In a cylindrical tube, fluid streams in the center flow faster than those at the tube wall, which results in a radially parabolic distribution in axial fluid velocity. This nonuniformity of axial velocities in the interstices in a packed bed also causes substantial peak broadening in packed columns.