Analysis Of Rheological Behavior Of Complex Emulsion Globules With Asymmetric Internal Structures

Based on the rapid development of microfluidic emulsion technology and other interdisciplinary technologies,the functional compound emulsion prepared has a great application prospect in the fields of effective release and targeted transport of drugs,removal of heavy metals in the environment,chemical reaction in microreactors and production of food,cosmetics and medicine.However,the functional complex emulsion prepared by microfluidic technology achieve the purpose of practical application only under effective control.Therefore,the research on controlled release and rheological behavior of compound emulsion have become hot topic.In this paper,the rheological behavior and motion mechanism of double layers emulsion(CEGs)with asymmetric internal structure in the cross-like microchannel are analyzed by using the two-dimensional spectral boundary integral method firstly.In addition,rheological problems such as the deformation and breaking of the emulsion in the contraction-cross microchannel are explored.The rheological behavior and motion mechanism of complex emulsion globules(CEGs)containing three daughter droplets(DDs)are investigated by using the numerical method of boundary integral method,two of the daughter droplets are arranged on non-axial positions.The asymmetric distribution of the three daughter droplets(DDs)induces the asymmetric outer shear force and drag force of complex emulsion globules(CEGs)in modest symmetrical extensional flow,which induces the directional or inversed motion of the complex emulsion globules(CEGs).The motion direction of complex emulsion globules(CEGs)is affected by factors such asymmetric parameter A_s,capillary number Ca and viscosity ratioλ.By studying the displacement and velocity curves of motion,we can clearly know the motion of complex emulsion globules(CEGs)in microchannel;In combination with interfacial curvature,internal pressure distribution and outer drag force,the motion mechanism of complex emulsion globules(CEGs)can be analyzed.On this basis,it can be judged whether the complex emulsion globules(CEGs)still follow the motion mechanism of simple eccentric emulsion globules(SEEGs):The asymmetric distribution of the daughter droplets(DDs)makes the asymmetric deformation of the complex emulsion globules(CEGs).The deformation of this structure leads to different curvature on both sides of the complex emulsion globules(CEGs).Therefore,the pressure on the left and right sides of the complex emulsion globules(CEGs)is different.In addition,the outer drag force also varies with the above parameters.Driven by internal pressure difference and outer drag force,complex emulsion globules(CEGs)produces directional or inversed motion,which is consistent with the motion mechanism of simple eccentric emulsion globules(SEEGs).At the same time,the movement of internal daughter droplet(DDs)may also affect the controllable release of complex emulsion globules(CEGs).The results investigated in this paper further prove the mechanical mechanism of the oriented shift of the complex emulsions globules,and are helpful to the controllable movement of soft globules driven by the asymmetric curvatures.Based on the universal integral equation of the boundary,the rheology behavior of emulsion is investigated in contraction-cross microchannel by setting the initial diameter of emulsion parameters,capillary number and viscosity ratio.Simple emulsion in the above microchannel will appear tensile deformation and breaking phenomenon.All the above numerical methods and boundary integral equations are compiled in Fortran programming language and running on Compaq Visual Fortran 6platform.