MechE Colloquium: Let droplets drop the temperature: Enhancing heat transfer using droplets
Event details
| Date | 15.09.2026 |
| Hour | 12:00 › 13:00 |
| Speaker | Prof. Patricia Weisensee, McKelvey School of Engineering, Washington University in St. Louis |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
Abstract: We experience and rely on droplets almost every single day of our lives: some more familiar (the shower in the morning, the rain on our way to work, printing a documents once at work, etc.), some less obvious (atmospheric water harvesting, thermal management & power generation, materials manufacturing and processing). Yet we hardly ever think about them – we take them for granted. In this talk I will show that droplets aren’t only ubiquitous in both nature and industrial processes, but also a complex and fascinating research subject that still holds many mysteries to be solved. In my research group, we are especially interested in the coupling of fluid dynamics, heat transfer, and phase change (condensation or evaporation) during the interaction of droplets with solid or other liquid surfaces.
In this presentation, I will introduce two examples of such interactions: 1) droplet impact and evaporation/boiling dynamics on heated surfaces, and 2) dropwise and pseudo-dropwise condensation on different kinds of surfaces. For example, on so-called lubricant-infused surfaces, lubricant wetting ridges surrounding droplets introduce an attractive capillary force, leading to self-propelled and gravity-independent droplet motion, which efficiently clears the surface for frequent re-nucleation and enhances condensation rates. Droplet self-propulsion can also be observed when condensing vapors of fluid mixtures on bare surfaces. On the other hand, restricting the mobility of droplets can be advantageous during droplet evaporation. Interestingly, when droplets impact a heated surface, the creation of additional contact lines, either through wettability-patterning the surface or the formation of an entrapped air bubble, does not significantly alter the heat transfer performance. Instead, convection (at early times) and conduction (at later times) dominate heat transfer, meaning that the addition of – for example – metallic posts with high thermal conductivity on the surface can effectively increase heat transfer rates in these scenarios.
Biography: Dr. Weisensee is an Associate Professor in the Department of Mechanical Engineering & Materials Science at Washington University in St. Louis (WashU). She earned her PhD in Mechanical Engineering from the University of Illinois at Urbana-Champaign (UIUC) in 2016. She received a Diplom-Ingenieur in Mechanical Engineering from TU Munich in 2013 and also holds a M.S. in Materials Sciences from UIUC (2011). At WashU, Dr. Weisensee leads the Thermal Fluids Research Group, which focuses on understanding the interplay of fluid dynamics and heat transfer of droplets and other multi-phase systems, with applications in thermal management, water harvesting, additive manufacturing, and droplet interactions with natural and engineered systems. To fundamentally study these thermal-fluidic interactions, her group combines multiple experimental techniques, such as high-speed optical and infrared (IR) imaging, interferometry, confocal fluorescence microscopy, and conventional heat transfer measurements. Dr. Weisensee is a recipient of the NSF CAREER Award, the NASA Early Career Faculty Award, the AFOSR YIP Award, the 2014 Siemens Energy Award, the 2020 ASME ICNMM Outstanding Early Investigator Award and 2025 micro Flow and Interfacial Phenomena Leadership Award, as well as the St. Louis-wide 2020 Emerson Excellence in Teaching Award.
In this presentation, I will introduce two examples of such interactions: 1) droplet impact and evaporation/boiling dynamics on heated surfaces, and 2) dropwise and pseudo-dropwise condensation on different kinds of surfaces. For example, on so-called lubricant-infused surfaces, lubricant wetting ridges surrounding droplets introduce an attractive capillary force, leading to self-propelled and gravity-independent droplet motion, which efficiently clears the surface for frequent re-nucleation and enhances condensation rates. Droplet self-propulsion can also be observed when condensing vapors of fluid mixtures on bare surfaces. On the other hand, restricting the mobility of droplets can be advantageous during droplet evaporation. Interestingly, when droplets impact a heated surface, the creation of additional contact lines, either through wettability-patterning the surface or the formation of an entrapped air bubble, does not significantly alter the heat transfer performance. Instead, convection (at early times) and conduction (at later times) dominate heat transfer, meaning that the addition of – for example – metallic posts with high thermal conductivity on the surface can effectively increase heat transfer rates in these scenarios.
Biography: Dr. Weisensee is an Associate Professor in the Department of Mechanical Engineering & Materials Science at Washington University in St. Louis (WashU). She earned her PhD in Mechanical Engineering from the University of Illinois at Urbana-Champaign (UIUC) in 2016. She received a Diplom-Ingenieur in Mechanical Engineering from TU Munich in 2013 and also holds a M.S. in Materials Sciences from UIUC (2011). At WashU, Dr. Weisensee leads the Thermal Fluids Research Group, which focuses on understanding the interplay of fluid dynamics and heat transfer of droplets and other multi-phase systems, with applications in thermal management, water harvesting, additive manufacturing, and droplet interactions with natural and engineered systems. To fundamentally study these thermal-fluidic interactions, her group combines multiple experimental techniques, such as high-speed optical and infrared (IR) imaging, interferometry, confocal fluorescence microscopy, and conventional heat transfer measurements. Dr. Weisensee is a recipient of the NSF CAREER Award, the NASA Early Career Faculty Award, the AFOSR YIP Award, the 2014 Siemens Energy Award, the 2020 ASME ICNMM Outstanding Early Investigator Award and 2025 micro Flow and Interfacial Phenomena Leadership Award, as well as the St. Louis-wide 2020 Emerson Excellence in Teaching Award.
Practical information
- General public
- Free