Analysis Of Static And Dynamic Behavior Of Heavy Droplets On Micro-nano Secondary Structure Surface

In recent years,inspired by the “Lotus Effect”,researchers have made various surfaces with excellent properties by mimicking the micro-nano secondary structure surface of the lotus leaf.The superhydrophobic surface has been widely used in the fields of antifreeze,self-cleaning and droplet manipulation due to its wettability.The static and dynamic behaviors of droplet on the surface are an important criterion for evaluating superhydrophobic properties.Based on the existing theoretical models,this paper studied the static and dynamic behaviors.The main research contents and results are as follows:1、Aiming at the tiny liquid droplet,a calculation method for predicting the equilibrium contact angle of the droplet on the heterogeneous micro-nano secondary structure surface was proposed by thermodynamic method without considering the gravity.Compared with the Herminghaus model,Patankar model and experimental data,the accuracy of the proposed method was proved.The reduced order method was used to prove that this method is an extension and extension of the existing theory.2、Considering the influence of gravity on the droplet,a numerical model for simulating heavy droplet morphology on surface was proposed based on the finite difference method and nonlinear optimization method.The simulation results were compared with the lotus leaf experiment and the Lubarda model to verify the accuracy.By studying the effects of the size of the surface structure and material hydrophobicity on the morphology of the droplet,it was found that the first generation nanostructure has much larger influence on the morphology of the droplets than that of the second generation microstructure and the substrate.3、Using the established heavy droplet model,taking the mutual transformation of the C-C state and the W-W state as an example,the transition of the contact state of the droplet on the surface and its energy barrier was studied.It was found that when the surface structure has a small relative spacing and a large relative height,the droplet easily changes from the W-W state to the C-C state,and the droplet is apt to be in the C-C state.4、Using the established heavy droplet model,it was found that the droplet in the C-C state has a smaller contact angle hysteresis and tends to roll on the surface by studying the effects of the contact state and the size of the surface structure on the contact angle hysteresis,which is of significance for preparing superhydrophobic surfaces.In this paper,the thermodynamic method was proposed to simulate the static and dynamic behaviors of the droplet on the micro-nano secondary structure surface.This method provides a valuable method for studying the superhydrophobic surface properties and optimizing the surface structure.