**Preface**

Crystallization is a key operating unit for the effective separation and purification of solid products. To enhance product quality and lower production costs, comprehending and controlling the crystallization process is now crucial. The research that focuses on the basic principles of nucleation, growth, breakage, and agglomeration in crystallization, the choice of crystallization methods like continuous crystallization, and the operation technology and control methods in the crystallization process have all made significant advancements and great progress in recent years. As a complex physical and chemical process involving many parameters and variables, the characteristics of strong coupling, nonlinearity, and large lagging in the crystallization process are very prominent, which greatly increases the complexity of process research and design as well as the challenge of quantifying process stability and reliability. Based on this, in recent years, accurate inline or online monitoring measurement and process analysis technical tools have become the focus of breakthroughs, which have achieved rapid development and application in guiding crystallization process regulation and optimizing crystallization processes. At the same time, against the background of digitalization, automation, and intelligence in the crystallization process, it has continuously promoted the development of the simulation calculation field by constructing mathematical models to describe and study complex processes. Especially in simulation technology of molecular dynamics and hydrodynamics, through mathematical modeling and multi-physical field simulation, dynamic data of multi-scale and cross-time and space can be provided, which has become an effective tool for in-depth research. The application of artificial intelligence technology such as machine learning will also become an important direction of crystallization process research in the future.

Therefore, this Special Issue includes 12 excellent works, covering a broad spectrum of topics from the study of crystallization process research and simulation calculation. The topics include, but are not limited to, the following:

Crystallization process analysis and control;

Secondary crystallization process;

Crystallization process strengthening;

Cocrystallization;

Continuous crystallization;

Dynamic simulation.

We hope that this Special Issue can serve as an open platform for scientists, graduate students and engineers working in the field of crystallization to exchange and publish the latest research results.

We deeply appreciate the outstanding research work of all authors. We are also very grateful to Mr. Mars Tan from the Editorial Office for his continuous assistance and support, which enabled our Special Issue to be successful.

> **Mingyang Chen, Jinbo Ouyang, and Dandan Han** *Editors*
