What is it about?
When engineers simulate air or liquid flows, they often use a method called large-eddy simulation (LES). This technique looks at the big swirls directly and estimates the effect of the small ones. To work, it needs a rule — called a “length scale” — to decide which swirls are resolved and which are modeled. The rule most people use can give poor results when the grid of the simulation is stretched or irregular, which happens a lot in real-world problems. In our study, we propose a new, very simple rule: the rational length scale. It makes the simulations much less sensitive to grid problems, while being just as easy to use. We tested it in different flow situations and showed it works better and more consistently than the old definition.
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Why is it important?
Reliable turbulence simulations are key to designing safer and more efficient technologies, from airplanes to energy systems. Our new method is easy to adopt in existing software and helps ensure trustworthy results even on complex grids, bringing high-fidelity simulations closer to real-world applications.
Perspectives
The new approach can be plugged into existing turbulence models with almost no extra cost. Next steps include testing it in more practical flows, such as those with walls, heat transfer, or multiple fluids. Because it is simple, robust, and widely applicable, we expect it could become a standard tool for both researchers and engineers.
Francesc Xavier Trias Miquel
Technical University of Catalonia
Read the Original
This page is a summary of: A rational length scale for large-eddy simulation of turbulence on anisotropic grids, Physics of Fluids, August 2025, American Institute of Physics,
DOI: 10.1063/5.0277423.
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