Hydrodynamics of laminar flow through dimpled pipes

摘要

Laminar flowthrough a dimpled pipe has been investigated with a focus to determine therelationship between hydrodynamic resistance and dimple geometry. Using aperiodic solution domain, in–line dimples were simulated with diameters thatvaried from 0.125mm to 2mm (with a pipe diameter of 6 mm). It was found thatfor small dimples, the flow does not enter into the dimple to forming acoherent recirculation zone. On the contrary, as the dimple diameter increases,a recirculation zone forms and moves in the downstream direction for increasingdimple size. The flow patterns within the dimple are connected to changes ofhydrodynamic resistance. For dimples whose sizes are small enough to preventrecirculation, the flow resistance is constant with dimple size. Once thedimples become sufficiently large to allow recirculation, there is an inverserelationship between flow rate and pressure drop. These findings allowoptimization of hydrodynamic performance when a balance between pressure drop,flow rate, and wall mass transfer is required.