Numerical Simulation Study Of Droplets Impacting Stainless Steel Fiber Based On OpenFOAM

Droplet breaking and dispersion are very commonly physical phenomena in daily life,such as the atomized droplets in the spray tower for industrial exhaust gas treatment,the pesticide sprayed in the form of small droplets in agriculture,and the atomized combustion of gasoline in automobile engines.The dispersion of droplets increases the surface area of the liquid,which has a significant impact on the physical contact and transfer and chemical reactions of the multiphase flow system.This phenomenon has been widely used in physics,chemistry,biology,medicine,materials and other disciplines.The method for droplet breaking and dispersion is relatively mature.Recent studies have found that the breaking,coalescence,and flow behavior of liquid droplets can be effectively adjusted by changing the wettability of a solid surface,that is,by adjusting its micro-/nano-structure or surface energy,thereby affecting the "transport and reaction" performance.Using high-speed imaging,CT scanning to observe the macro-size(millimeter)flow of liquids,transmission or scanning electron microscopy and other technologies to observe the micro-size(micro-nano)solid surface are relatively mature technologies.However,it is still challenging to accurately observe the flow and dispersion of liquid on solid micro-/nano-surfaces.Based on this issue,on the basis of previous experimental research,this work employed the open source software OpenFOAM as a simulation tool to establish a two-dimensional physical model and a three-dimensional physical model respectively,and use the two-phase immiscible solver interFoam,solver interFlow which has optimized the surface capture algorithm to solve the problem,and myinterFlow(a solver that further embeds the dynamic contact angle model)were used as the solver for the numerical simulation of the dispersion process of droplets impacting the stainless steel fiber.The simulation results will be compared with previously experimental results.It is expected that the analysis results can be used to guide the experimental research.The main research results are as follows:(1)On the basis of the two-phase flow solver interFlow that has been optimized by previous surface capture algorithms,the further optimized twophase flow solver myinterFlow was obtained by embedding the dynamic contact angle model;(2)According to the operation condition of three typical flow patterns by experimental stuides of droplet impacting fiber,the interFoam solver,the interFlow solve,and the myinterFlow solver were used to carry out the twodimensional simulation.By analyzing the flow pattern,pressure field,and velocity field,it is determined that the result obtained by using the myinterFlow solver is more reasonable than the other two;(3)Three-dimensional simulation of the droplet flow under different impact speeds were carried out:with the increase of the impact speed,the maximum spreading length of the droplet gradually increased,the time to reach the maximum spreading decreased,the maximum droplet surface area increased,and the average growth rate before reaching maximum droplet surface area increased.As the impact velocity gradually increased from 1 m/s to 5 m/s,the maximum spread length gradually increased from 3.8 mm to 5.8 mm,and the peak droplet surface area gradually increased from 35 mm2 to 100 mm2.