ISS: Fluid Resonance Instability for Enhancing Heat Transfer

When thin layers of liquid with a free surface are heated, they create motion called Marangoni flows. These flows occur because of changes in surface tension when the fluid is heated. The Marangoni flows can cause the thin layers to break apart and dry out. This dry-out is detrimental to several materials processing techniques such as optical film deposition and 3D printing. It is also harmful to heat exchangers that are crucial to high computing device performance. Researchers believe that vertical shaking of the thin fluid layers can prevent flows from occurring and therefore stave off dry out. To test this idea, experiments will be conducted in microgravity on the International Space Station to avoid the interference caused by Earth's gravity. Besides scientific discovery this project promotes diversity and inclusion by offering educational opportunities for graduate, undergraduate, and K-12 students. It fosters critical thinking, experimental design, and communication skills through STEM outreach, enriching research with diverse perspectives. The main goal of this research is to determine how and when parametric forcing can prevent Marangoni flows in non-isothermal thin fluid layers and under what conditions they can lead to resonance. The proposed microgravity experiments with multiple test-fluid systems will validate theoretical predictions. Importantly, they will isolate the physics of parametric-forcing dynamics without interference from buoyancy-driven convection. The intellectual merit of the study is that it will provide compelling evidence that there are two regimes of parametric forcing on thermo-capillary flows: a low-frequency regime where such flows can be eliminated and a high-frequency regime where it cannot, but where resonance occurs and where heat transfer can be substantially increased in a closed system. The first regime finds applications in materials processing of thin films and in additive manufacturing. The second regime finds applications in micro-reactors and in micro heat pipes. These applications have substantial broad impacts and benefits to life on Earth, such as in the formation of thin optical films, directed energy deposition, and in the thermal cooling of high-speed computational devices. The study also has broad translational application to the physics of electrostatic and magnetic-induced resonance instability. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.