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When a water drop is placed on a hot solid surface, it either undergoes explosive contact boiling or exhibits a stable state. In the latter case, the drop floats over an insulating layer of vapor generated by rapid vaporization of water at the surface/drop interface; this is known as the Leidenfrost state. Here, we discuss a previously unrecognized steady state in which a water drop "stands" on a hot smooth surface. In this state, the drop stabilizes itself with partial adhesion on the hot surface, leading to unique deformation and rotation behavior reminiscent of Sufi whirling-a form of spinning dance. Our analysis of this standing Leidenfrost state reveals the underlying mechanisms that drive the drop's stable partial adhesion and subsequent deformation with rotation. The heat-transfer efficiency of this standing state is up to 390% greater than that of the traditional floating Leidenfrost state.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10410755 | PMC |
http://dx.doi.org/10.1073/pnas.2305567120 | DOI Listing |
ACS Appl Mater Interfaces
September 2025
School of Manufacture Science and Engineering, School of Information Engineering, Key Laboratory of Testing Technology for Manufacturing Process, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China.
The Leidenfrost effect enables near-frictionless droplet transport by suspending droplets on vapor layers, making it pivotal for contact-free manipulation in microscale chemical reactions and material transport applications. Traditional ratchet structures that drive Leidenfrost droplet motion require the substrate material to be heated above the higher Leidenfrost point (LFP) critical temperature, which imposes significant demands on energy consumption and material heat resistance. Herein, we proposed a method that integrates femtosecond laser-induced deposition with femtosecond direct writing to fabricate a textured superwettable patterned surface, achieving directional droplet navigation at a notably low temperature of just 155 °C.
View Article and Find Full Text PDFACS Appl Mater Interfaces
August 2025
Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States.
In the Leidenfrost regime, droplets or sublimating solids can ratchet across asymmetric surface structures by viscous entrainment with the underlying vapor flow. As an extension to these liquid-vapor or solid-vapor ratchets, here, we investigate the solid-liquid self-propulsion of melting ice disks. On hydrophilic herringbones, ice disks self-propel due to the unidirectional flow of viscous meltwater.
View Article and Find Full Text PDFSci Rep
May 2025
Department of Mechanical Engineering, National Taiwan University, Taipei, 106319, Taiwan.
Leidenfrost drop can accelerate chemical reactions, offering great potential for droplet-based chemical reactors. By leveraging their motion on heated surfaces with micro-rachets, we demonstrate that mixing can be further enhanced through head-on collisions of two Leidenfrost drops. This study identifies three mixing stages.
View Article and Find Full Text PDFSmall
July 2025
State Key Laboratory of High-performance Precision Manufacturing, Dalian University of Technology, Department of Anaesthesiology, Central Hospital of Dalian University of Technology, Dalian, 116033, China.
The interaction of droplets with high-temperature solid surfaces is critical in processes like machining cooling and internal combustion engine operations. As surface temperature rises, droplets transition through distinct boiling regimes: film evaporation, contact boiling, transition boiling, and film boiling. In the film boiling regime, droplets are suspended on a vapor layer formed by their evaporation, known as the Leidenfrost effect, which occurs above the Leidenfrost point-the minimum temperature for this phenomenon.
View Article and Find Full Text PDFLangmuir
December 2024
Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States.
Patterned solid surfaces with wettability contrast can enhance liquid transport for applications such as electronics thermal management, self-cleaning, and anti-icing. However, prior work has not explored easy and scalable blade-cut masking to impart topography patterned wettability contrast on aluminum (Al), even though Al surfaces are widely used for thermal applications. Here, we demonstrate mask-enabled topography contrast patterning and quantify the resulting accuracy of the topographic pattern resolution, spatial variations in surface roughness, wettability, drop size distribution during dropwise condensation, and thermal emissivity of patterned Al surfaces.
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