Dynamics Simulation Based On Lattice Boltzmann Method And Experimental Research Of The Electrorheological Fluids

In recent years, the giant electrorheological fluids and polar moleculeselectrorheological fluids with high yield stress have emerged, but to meet the MPalevel requirement in the actual engineering application, there is still a certaingap.Therefore, electrorheological materials formula design work is still an importantsubject for scientific workers to solve, and the correct formula design work must bebased on the complete and accurate comprehension of the mechanism ofelectrorheological effect.From the existing literatures, the researches on themechanism of electrorheological effect are generally based on observing the static orrotating shear rheometer flow field, which cannot fully describe the dynamicsbehavior of electrorheological fluids under the effect of multi-field coupling.It’s worth noting that the characteristic scales to represent the time-space domainin electrorheological effect are very small, and time is recorded in millisecond; Spaceis usually measured in millimeter.From electrorheological fluids polarization model inearly researches to the recent dynamics simulation work, many scientists haveconsidered electric double layer, electroosmosis and electrophoresis, factors generallyconsidered liquid flow on microscales. This paper, based on the national naturalscience fund project(51075345), researches the dynamic behavior ofelectrorheological fluids under the effect of multi-field coupling from the aspects oftheory and experiment.Firstly, the process of the response to electrorheological fluids is approximatelyregarded as micro-scale flow, and based on the lattice Boltzmann method, the twophase flow model to represent the electrorheological fluids dynamics isestablished;And the behavior of electrorheological fluids dynamics under themulti-field coupling is simulated and researched, the results show that from the modelnot only the microstructure evolution process of solid phase particles can be obtainedbut also the rheological characteristics of electrorheological fluids.Secondly, in view of the fact that in researches on the mechanism of theelectrorheological effect, visualization experiment is relatively less conducted, avisual experimental platform is designed and made. The platform can realize thequantitative control of electric field intensity and flow velocity, as well as onlinecollecting the parameters of the micro dynamic structure, the information of the flowboundary and the macro-mechanical properties, all of which are caused by electrorheological fluids field..Finally, by visualization experiments, it is researched that the electrorheologicalfluids under the action of the static and multi-field coupling field, causesubmicroscopical dynamic structure changes.The experimental results show that inthe process of the response of the electrorheological fluid in static field, interficialeffect plays a leading role; in dynamic process, the microstructure ofelectrorheological fluids is mainly affected by the polarization force and fluid power;the information of the flow boundary is that the yielding fracture of the chain structurefirst occurs in the junction of the chain and the plate, which represents the micro-flowcharacteristics of velocity slip; Visualization experiments validate that thedownstream of the chain structure can capture the slip of upstream chain and freeparticles can form a more stable columnar structure.