ISS Experiments
Why it matters
On Earth, buoyancy and gravity-driven drainage hide many of the subtler forces acting at a liquid–vapor interface. In microgravity, surface tension, evaporation-driven temperature gradients, and Marangoni (surface-tension-gradient) flows dominate. That makes space experiments a clean test bed for the physics inside heat pipes, capillary pumped loops, and other passive thermal management devices, including those used on Earth at small scales.
Our approach
We analyze data from the Constrained Vapor Bubble (CVB) experiment flown on the International Space Station, available through the NASA Physical Sciences Informatics (PSI) database. Interferometric images of the liquid film are combined with multiscale phase change models (molecular to continuum) to back out interface temperatures, pressures, and flow fields. This lets us test common simplifying assumptions directly against flight data, such as:
- an isothermal liquid–vapor interface, and
- equal evaporation and condensation coefficients.
Key findings
- The interface is not isothermal. The resulting temperature gradients drive strong Marangoni flow in microgravity, with recirculation zones and stagnation points that match optical signatures seen in the flight data (Chakrabarti et al., Frontiers in Space Technologies, 2023).
- Evaporation and condensation coefficients are not interchangeable, and treating them as equal changes the predicted heat transfer (Chakrabarti et al., Nanoscale and Microscale Thermophysical Engineering, 2025).
This work was the core of Unmeelan Chakrabarti’s PhD dissertation (2026). It has been presented at ASGSR, NASA TFAWS, APS-DFD, and ASME IMECE, where it received an Outstanding Student Presentation Award.