Research On Simulation Of Crystal Growth Process And Dynamic Parameter Identification

Crystal morphology is the external manifestation of crystal structure,which is an important factor that determines properties of crystals.In the crystallization process,the growth of crystal can be affected by various external conditions,such as pH value of solution,additives,solvents,impurities and interfaces.In general,these external conditions are interrelated and restricted in both time and space,resulting in complex evolutionary behavior,in which the same substance shows different crystal morphologies,and further shows different physical and chemical properties,such as melting point,solubility,dissolution rate,stability and so on.The relationship between the growth rate and the influencing variables driving the growth during crystal growth can be studied to predict the crystal morphological characteristics by crystal growth kinetics.Therefore,it is of great significance to study the crystal morphology by using crystal growth dynamics to explore the crystal growth mechanism.For such complex processes involving multiple influencing factors,it is necessary to match the microstructures with macroscopic phenomena and study the dynamics of the system from a holistic point of view.The crystallization process can be regarded as a reaction diffusion system,and the factors affecting crystal growth in the system can be considered in terms of reaction and diffusion by dividing them into diffusion-related item and reaction-related item to reduce variables.Diffusion and reaction play different roles in regulating crystal structure,and their interactions constitute the key factors that affects the crystal morphology.With the rapid development of computer technology,the crystallization process can be simulated with suitable calculation tools.Cellular automata(CA)is a method for modeling the behavior of a system by simulating the interactions between subsystems.It is a method composed of a series of model rules,which is widely used to simulate the spatiotemporal evolution process of complex systems because of its simple rules of the component units and the high parallelism of local operations.Using cellular automata to construct crystal growth model to obtain crystal dynamics equation is of great help to guide industrial production to obtain crystal with ideal shape.In this work,the crystallization process is regarded as a generalized reaction diffusion system.In this process,the process of solute moving to the crystal surface is considered as diffusion,and the attachment to the crystal and the change of phase are considered as reactions.From a systematic point of view,the factors related to crystallization process are divided into reaction term and diffusion term.Snowflake is chosen as the research object in this work because of its rich crystal morphologies.Based on CA,the crystallization process of ideal water vapor into snowflake is simulated,and the influence of parameters on crystal morphology is studied by changing the model parameters.The crystal growth data obtained based on mass conservation and diffusion principles are fitted by regression algorithm to obtain the process dynamics,and the effects of reaction and diffusion rate on crystal morphology are quantitatively discussed.This work provides a new research method for studying how to produce products with specific crystal morphology in a directed way,and it is hoped to provide guidance for subsequent crystallization experiments to obtain effective crystal morphologies,reasonable synthesis and structural design of substances.