Measurement And Numerical Simulation Of Dynamic Water Transfer Properties Through Fabrics

The dynamic water transfer property of fabric refers to the diffusion ability of liquid water on the fabric,which is an important physical property of clothing fabrics and an important factor affecting clothing comfort.When the human body perspires sensitively,sweat is mainly transferred on the fabric in the form of liquid water.Therefore,the investigation of the dynamic water transfer properties of fabrics is significant for fabric development and research work of clothing comfort.It is a convenient and efficient method to study the dynamic moisture transfer performance of fabrics by applying computer image technology.In order to improve the measurement accuracy of the dynamic water transfer performance of fabrics,it is necessary to solve the key technical problems of the extraction of the wetting area and its edge in the process of image technology measurement.In this study,we constructed a system to measure the dynamic water transfer properties of fabrics based on infrared images.The infrared images were extracted from the infrared video recording the dynamic water transfer of fabrics,and then they were segmented,bilaterally filtered and binarized according to set parameters by the system to measure the dynamic water transfer properties of fabrics automatically.It has been proven that the system was applicable for calculating the wetting area of the fabric at any time during the dynamic water transferring,with high accuracy.15 woven fabrics were selected to conduct the dynamic water transfer experiment using the proposed method.The results revealed that the porosity of the fabric is an important factor in the dynamic water transfer.The lower the tightness of the fabric,the greater its air permeability and porosity.The higher porosity leads to more capillary effect formed in the fabric,which promotes the diffusion of water inside the fabric.However,when the spacing of fabric yarns is too large,the capillaries cannot be formed by the voids between the yarns,and the diffusion of water mainly transfer in the microporosity between the fibers within the yarn,resulting in a decline of water diffusion.In this study,we also analyzed the regulation of the wetting area of fabrics during dynamic water transfer.The entire water diffusion process was divided into two phases: a fast-wetting phase and a slow-wetting phase,and inflection points and steady-state points were defined to delineate the two phases.The results showed that there was a linear correlation between the time of the inflection point and the steady-state point and the ratio of the wetting area at the inflection point and the steady-state point is around 52%.A predicting model for the dynamic transfer of finite water in fabrics was proposed by identifying and analyzing the key points in the dynamic water transfer process.Verification of the experimental data proved that the model is applicable for predicting the trend of fabric wetting area and providing a reference for the comparison of fabric moisture transfer properties.To develop a new method for studying the water transfer properties of fabrics,a numerical simulation of the dynamic water transfer was conducted.An equivalent model for fabric was constructed using COMSOL Multiphysics.The coupling analysis of dynamic moisture transfer of fabric was carried out by applying Darcy’s law and porous properties of fabric,and the whole process of water transfer as simulated.The influence of dynamic wetting radius,water volume fraction(water distribution in fabric)and yarn porosity on water transfer distance was analyzed using the simulation results.The trend of simulated fabric wetting radius was compared with the experimental results,which proved that the numerical simulation results had good accuracy and reliability.