Research

We investigate momentum transport and boundary-layer development at the interface between free-flow regions and porous materials using high-resolution microfluidic experiments. Our work combines Hele–Shaw micromodels, micro-PIV velocimetry, and analytical Darcy–Brinkman modeling to reveal how permeability, porosity, and interfacial geometry govern slip velocity, channeling, and transport across scales. These studies provide experimentally validated frameworks for coupled free-flow/porous-media systems relevant to microfluidics, energy systems, transpiration cooling, filtration, and transport in engineered porous structures. Recent results demonstrated permeability-dependent boundary-layer formation, experimentally validated viscosity-invariant slip length behavior, and exact analytical solutions for laminar flow near permeable interfaces.

Microfluidic convergent nozzles enable the generation of ultra-thin planar liquid sheets that subsequently atomize into highly controllable sprays, offering a compact and efficient approach for thermal management in confined spaces. By tailoring nozzle geometry and operating conditions, the morphology, breakup dynamics, droplet-size distribution, and cooling footprint of the spray can be precisely controlled. These planar sheet sprays provide localized high heat-flux cooling while occupying significantly smaller volumes than conventional spray systems, making them attractive for electronics cooling, aerospace thermal management, and advanced energy technologies.

Our research combines high-speed imaging, laser-based spray diagnostics, and infrared thermal imaging to investigate the coupled fluid-dynamic and heat-transfer mechanisms governing sheet formation, atomization, and spray impingement cooling. Through experimentally validated scaling frameworks, we aim to establish predictive design methodologies for next-generation compact spray-cooling systems.