TY  - EJOU
AU  - Tong, Wei 
AU  - Peng, Chuyi 
AU  - Zhao, Yugang 

TI  - Morphologies of Freezing Water Droplets: Mechanisms, Effects of Scenarios and Composition
T2  - Frontiers in Heat and Mass Transfer

PY  - 
VL  - 
IS  - 
SN  - 2151-8629

AB  - The freezing of water droplets represents a fundamental phase-change phenomenon with far-reaching implications across anti-icing technologies, additive manufacturing, cryopreservation, and atmospheric science. The solidification process is governed by a complex interplay of heat transfer, phase-change kinetics, interfacial phenomena, and solute redistribution in multicomponent systems. The final frozen morphology emerges from competition among multiple physical mechanisms: the degree of supercooling, recalescence and dendritic growth, freezing front propagation, freezing-induced volume expansion, vapor release and frost halo formation, and freezing segregation coupled with interfacial flow. This review provides a comprehensive synthesis of droplet freezing morphology, organized around three interconnected themes. First, we examine the fundamental physical mechanisms governing droplet solidification and their roles in driving morphological change. Second, we survey morphological outcomes across distinct scenarios, sessile droplets on supercooled substrates, sessile droplets in supercooled chambers, impinging droplets onto supercooled substrates, and acoustically levitated droplets, highlighting how thermophysical conditions determine the subsequent freezing pathway. Third, we explore how droplet composition (dissolved gases, ions, organic solvents, and nanoparticles) and special cases (bubbles and liquid marbles) influence morphological evolution. Finally, we discuss the modulating effects of substrate properties, external fields, and ambient conditions on freezing morphology. By integrating experimental observations with theoretical models, this review establishes a unified framework for understanding droplet freezing morphology and outlines key directions for future research.
KW  - Droplet freezing; recalescence; volume expansion; substrate wettability; ice morphology

DO  - 10.32604/fhmt.2026.088107