Effect of superimposing oscillatory flow in a milli‐channel with static internals—A numerical study

Abstract

Superimposition of oscillatory flow over the axial flow is expected to further enhance the mixing phenomenon based on the limited reported literature. A detailed study on the physics of such superimposed flows will be useful to widen the scope of application of static mixers with superimposed oscillatory flow in continuous modes of operation for several purposes. The flow behaviour of a water–vinyl acetate system in a milli‐channel with static internals is studied under the laminar flow regime using computational fluid dynamics (CFD) as a tool. A CFD model is developed and validated with reported literature on a Kenics static mixer. The effect of oscillatory flow superimposed over the axial flow in a milli‐channel is studied for Ren = 5 and Reo = 20–65. Residence time distribution (RTD) studies have been carried out and compared numerically for two different geometries, (1) tube without an internal and (2) tube with internals, for two different velocities, (1) net axial velocity and (2) superimposed oscillatory velocity. Results of these RTD studies indicate a sharp distribution in the channel with static internals having superimposed oscillatory flow followed by the channel with static internals with net axial velocity and then a tube without an internal. It is also found that Péclet number (Pe) for static internals with oscillatory flow > net axial flow > tube without an internal (736 > 641 > 315). Further, velocity magnitude, pressure, and Q‐criterion are discussed in detail to understand fluid flow behaviour in the milli‐channel. From this research, it is understood that superimposing oscillatory flow along with static internals resulted in enhanced mixing when compared with a tube with no internal.