Numerical Simulation Of Flow And Mixing Characteristics In A Micromixer

In recent years,the micromixers are widely used in chemical synthesis and biological pharmaceutical,etc.these areas require two or more liquid fluid in it reach high mixing efficiency.However,due to the fluid flow in the micromixers are generally low Reynolds number,the flow of fluid in its interior is laminar flow.The dynamic force of fluid mixing is molecular diffusion,and usually liquid molecular diffusion is slow,which requires the microchannel to be long enough for the fluid to stay in its interior for a long time,but this will increase the production costs.For these reason,the method of mixing unit is proposed to improve the mixing efficiency of micromixers.In this paper,on the basis of the traditional Y-shaped microchannel,mixing units with different structures(centrifugal mixing elements,bifurcated mixing elements and obstacle mixing elements)are introduced into the Y-shaped micromixer.the fluid in the mixing element generates chaotic stream,which then improve the mixing efficiency of the micromixers,so as to design the micromixer mixing efficiency.The results show that,at Reynolds Numbers 1 to 60,the mixing index and pressure drop of the fluid in the micromixer are closely related to the mixing element.The conventional YSM,since it does not contain a mixture element,The fluid is laminar flow in its interior.It has a maximum mixing index of 0.16;The new micromixer generates a chaotic flow at the mixture element due to the presence of the mixture element,and the mixing efficiency is higher than that of YSM.YSMHC(R1.5)and YSMHC(R1)with semi-cylindrical centrifugal mixture element rank first,their maximum mixing index is 0.99,and improve 6.2 times comparing with YSM.YSCCSAR,YSCRSAR and YSCRCSAR with semi-cylinder and centrifuge mixing element rank second.Its maximum mixing index is 0.97,improving 6.1 times comparing with YSM.YSDB and YLDB with the obstacle mixing element rank third,and have a maximum mixing index of 0.97 and 0.96,improving 6.1 and 6 times comparing with YSM.YCSAR and YRSAR with split and recombination mixing element ranked fourth,and have a maximum mixture index of 0.92 and 0.86,which improved 5.7 and 5.3 comparing with YSM,respectively.For the pressure drop,YSM is 205Pa.YSDB and YLDB containing the obstacle mixing element rank first,and its maximum pressure drop is 747 and 608 Pa respectively,which improve 3.6 times and 3 times compared with YSM.YSMHC(R1.5)and YSMHC(R1)with semi-cylindrical mixing element rank second,and maximum pressure drops are 320 and 603Pa,improvement of 1.6 and 2.9 times comparing with YSM.YSCCSAR,YSCRSAR and YSCRCSAR containing semi-cylinder centrifugal and bifurcated mixing elements rank third.Its maximum pressure drop is 291 Pa,1.4 times higher than YSM.The fourth largest is YCSAR and YRSAR with a forked structure,with a maximum pressure drop of 252 Pa and 243 Pa,improvement of 1.2 and 1.1 times comparing with YSM,it can be concluded that the pressure drop of the micro-mixture is proportional to the mixing index.