💨🌊 Physical Explanation and Modeling of Wind and Water Dynamics
🦠 Epidemiology and Fluid Mechanics
My study shows that even a small number of infected individuals who travel between communities — what we call “geographical spreaders” — can dramatically influence how a disease spreads. Using a mathematical model, we found that just 1–10% of mobile infected people can speed up the outbreak and create organized patterns like waves or hotspots in places far from the original source.
These findings highlight that movement — how far and how often people travel — can be just as important as infection rates when it comes to understanding and controlling outbreaks. Even if most people stay put, a few movers can reshape the entire course of an epidemic.
🧱 Turbulence and the Wall
A fundamental problem in fluid mechanics is explaining energy dissipation in turbulent flows due to friction at boundaries (wall friction). This issue has significant implications for the transport of oil and methane across continents.
Traditional analyses rely on empirical tools such as Nikuradse/Moody diagrams to describe friction factor as a function of Reynolds number and relative roughness. My work derives a first-principles physical explanation based on turbulence theory, unifying these diagrams into a single curve by using the turbulence energy spectrum.
📄 Published in Physics of Fluids, 2021
🌿 Turbulence and the Vegetation
This research examines how boundary roughness (e.g., vegetation) affects flow structure and bulk flow properties.
- Developed an asymmetric eddy diffusivity model for vegetated flows.
- Derived a universal velocity distribution equation using asymptotic analysis.
- Applied numerical reactive transport modeling to quantify contaminant absorption by vegetation in floating treatment wetlands.
The study links microscale physics to field-scale contaminant removal efficiency, confirming results against empirical data.
📄 Published in Environmental Research Letters, 2019
🪸 Turbulence and Sediments
This work introduced one of the first models for sediment settling velocity in turbulent flows using perturbation analysis.
Traditionally, settling velocity is assumed equal to still water, but my work shows turbulence reduces settling velocity via:
- Basset history force
- Virtual mass effects
This challenges assumptions used in Rouse’s equation and explains discrepancies with turbulent Schmidt number formulations. The derived comprehensive equation includes all turbulence scales, from bulk flow to Kolmogorov scale, revealing:
- Scaling with Reynolds number
- Limits of local mixing-length models
- Rouse equation as a special case
📄 Under review at Physical Review Letters, 2025
🏞️ Sediment Carrying Capacity from Turbulence Theory
Channel vulnerability to scour and deposition remains a key engineering concern, especially under climate pressure. Existing models often lack direct links between sediment physics and observations.
My research derives a universal prediction formula starting from:
- Turbulent Kinetic Energy (TKE) equations
- Shear stress budget
This formulation spans five orders of magnitude of historic measurements and supports:
- Climate adaptation infrastructure
- Engineering of resilient scouring/deposition systems
The model bridges microscale turbulence and bulk-scale sediment transport, enabling more reliable and physically grounded sediment predictions.