What is it about?
This study investigates how fluids circulate naturally through porous materials, a process crucial for applications like storing carbon dioxide in deep aquifers or extracting geothermal energy. Traditionally, scientists relied on the Darcy-Oberbeck-Boussinesq equations, which assume that the efficiency of mass transfer—measured as the Sherwood number—depends purely on the concentration gradient, known as the Rayleigh number. We challenged this traditional view by running extensive, pore-scale resolved direct numerical simulations (DNS) of fluids flowing around microscopic circular and square obstacles. We discovered that the physical shape, arrangement, and porosity of these microscopic pores heavily dictate how large "mega-plumes" of fluid form and behave within the medium.
Featured Image
Photo by Marvin Sagisi on Unsplash
Why is it important?
Our findings resolve a major, long-standing conflict between theoretical mathematical predictions and actual experimental observations. By demonstrating that natural convection does not scale linearly at high Rayleigh numbers, we developed a brand new mathematical correlation that directly factors in the porosity and physical geometry of the material. This breakthrough is uniquely timely for tackling massive environmental and engineering challenges, such as optimizing enhanced oil recovery or ensuring the stability of groundwater contaminant transport. Accurately predicting fluid behavior based on microscopic geometry allows engineers to design significantly more efficient and reliable systems for underground applications.
Perspectives
Working alongside Stefan and Yan on this project was an immensely rewarding experience for me. We spent countless hours pushing the limits of our computational solver, dealing with meshes of up to 29 million cells, just to prove that microscopic geometry cannot be ignored when predicting macroscopic convection. Watching those long-living mega-plumes finally emerge and validate our hypothesis in the simulation data was a brilliant moment of discovery. I genuinely hope this work bridges the gap between theoretical fluid dynamics and practical environmental engineering. It is easy to get lost in high Rayleigh numbers and dense algorithms, but ultimately, understanding these complex porous flows is essential for engineering safe, long-term carbon sequestration to protect our planet's future.
Andrey V Kuznetsov
North Carolina State University
Read the Original
This page is a summary of: Prediction of pore-scale-property dependent natural convection in porous media at high Rayleigh numbers, International Journal of Thermal Sciences, September 2022, Elsevier,
DOI: 10.1016/j.ijthermalsci.2022.107635.
You can read the full text:
Contributors
The following have contributed to this page
