Spreading Characteristics Of Volatile Liquid Drop On The Substrate

The spreading of immiscible liquid drops on a substrate involves rich physical phenomena.In order to investigate the underlying physical mechanisms,this project studies the spreading characteristics of volatile liquid drops on a substrate,explores the coupling mechanism between drop spreading dynamics and Marangoni effect,and achieves precise control of drop spreading to improve the heat and mass transfer efficiency.The implementation of this project is beneficial to enrich the theoretical understanding of spreading characteristics of liquid-liquid interface systems and provide new ideas and solutions for the technical barriers that exist in engineering applications.In terms of theoretical research,based on the mechanism of volatile liquid drop spreading on a substrate,the scaling relationships between the characteristic radius and time of drop spreading are derived based on the spreading states,spreading coefficients and surface energies of drops on solid and liquid substrates.The effect of Marangoni effect at the liquid-liquid interface on the spreading of volatile liquid drops on the liquid-solid surface is analyzed from the aspects of concentration and temperature effects.From a theoretical perspective,the R-P instability on the liquid-liquid interface is explained.In terms of experimental research,a drop spreading experimental system is constructed to investigate the spreading characteristics of volatile liquid drops on isothermal,non-isothermal liquid-solid substrates,and low surface tension liquid substrates,revealing the spreading dynamics mechanism of volatile liquid drops on liquid-solid substrates.The experimental results show that with the increase of the liquid-solid ratio in the substrate,the peak value of the inner radius of volatile liquid drop spreading increases and the spreading time decreases.The outer ring of the drop forms a uniform inclination angle above the solid region of the liquid-solid substrate,and viscous stress and van der Waals force are key factors that inhibit spreading motion.Marangoni instability,R-P instability,and non-spreading modes are observed when volatile liquid drops spread on non-isothermal liquid-solid substrates.The critical temperature for mode switching is affected by the initial volume and IPA concentration of the drop.During the spreading process of volatile liquid drops on low surface tension liquid substrates,a dynamic wave-like structure is observed,and oil holes appear in the inner ring of the drop.From the center of the hole,a linear drop array is produced radially,and with the progressive oscillation of the edge of the oil hole,a hump is formed at the edge,causing the drop array to appear as a circular pearl structure.This project systematically studies the spreading characteristics of volatile liquid drops on substrates from two directions: liquid-solid and low surface tension liquid substrates,and provides important theoretical basis for industrial applications.