Study On The Experimental Verification For The Applicability Of Taylor's "Freezing" Hypothesis For Different Scale Turbulence

Taylor's "freezing" hypothesis was put forward by Taylor in 1938:the turbulence can be considered that the turbulence is frozen when the turbulence flows through the measuring instrument under certain conditions.This assumption is the key to judge whether the turbulence measured at one point in space can replace the observation results at any point along the trajectory of turbulence at the same time,which plays an important role in the study of turbulence and medium exchange.Therefore,it is of great practical significance to verify the applicability of Taylor's "freezing" hypothesis for the study of atmospheric fluid movement,energy exchange and pollutant diffusion.This thesis takes the method of applicability verification of Taylor's "freezing" hypothesis at different scales as the research objective.We propose the experimental method to verify the applicability of Taylor's "freezing" hypothesis on small and large scale by using the technology which is holographic interferometry and lidar remote sensing detection.The holographic interferometry technology is used to detect the state distribution and particle radius of the droplet particles simulated by the ultrasonic atomizer.According to the time correlation theory,the time correlation of the simulated droplet particle radius is calculated,and the time correlation of the particle radius is plotted.The temporal correlation curves of particle radii are drawn to verify the applicability of the Taylor's "freezing" hypothesis on small scale turbulence.An experimental verification method for the Taylor's "freeze" hypothesis of large-scale by combining the scanning and coherent Doppler wind measurement lidar.Aerosol clusters are used as tracers to carry out detection experiments in the way of combining space and time,vertical scanning images and fixed-point continuous observation images of aerosol clusters are obtained by inversion.The methods of area comparison and perceptual hash algorithm are used for comparing the image similarity.The applicable scope and constraint conditions of Taylor's"freezing" hypothesis under corresponding conditions are obtained by combining the comprehensive vertical scanning detection time,the continuous observation time of fixed pitch angle and the wind speed and direction information at the experimental time.The results of the study show that the assumption of Taylor's "freezing" in the atmosphere is conditional,which is directly related to the wind speed,direction and intensity of turbulence changes.The method is adopted that holographic interferometry verification is sensitive to small-scale microscopic particles,and the applicability of the Taylor's "freezing" hypothesis obtained from the verification provides a time-dependent theory for studying the formation mechanism of droplet collisions;The verification method combined with multiple lidar detection technologies is sensitive to the long-distance transport of aerosol clusters and pollutants.The applicability of Taylor's "freezing" hypothesis is verified and provides a theoretical basis and method for clarifying the transport law of pollutants and guiding the distribution of meteorological and environmental monitoring.