Large eddy simulation

Large eddy simulation (LES) is a computational method for turbulent flow that resolves large motions on a grid and models the effects of smaller, unresolved motions.

Spatial filtering: A mathematical operation that separates variations by spatial scale. Filtering defines which turbulent motions LES resolves and which it leaves unresolved.
Turbulence: Irregular fluid motion characterized by interacting fluctuations across a range of spatial and temporal scales. LES is designed to predict turbulent flows without resolving every fluctuation.
Direct numerical simulation: A fluid simulation that resolves all dynamically relevant turbulent scales without a turbulence closure model. DNS resolves scales LES models, but its computational cost grows sharply with Reynolds number.
Computational fluid dynamics: The use of numerical methods to solve equations governing fluid motion and related transport. LES is a major turbulence approach within computational fluid dynamics.
Subgrid-scale model: A closure model that represents the effects of motions smaller than a computational grid can resolve. It supplies the missing influence of unresolved eddies on the resolved flow.
Navier–Stokes equations: The differential equations describing momentum, mass, and energy transport in fluids. LES commonly starts from filtered forms of these governing fluid equations.
Reynolds-averaged Navier–Stokes equations: A formulation that averages fluid equations over time or an ensemble and models the resulting turbulence stresses. RANS models the full turbulent fluctuation field, while LES resolves its larger motions.
Aerodynamic noise: Sound generated by unsteady airflow interacting with surfaces, shear layers, or other flow structures. LES can capture unsteady flow structures that generate aerodynamic sound.
Smagorinsky model: A subgrid-scale closure that estimates turbulent viscosity from the local strain rate and grid scale. This widely used model turns unresolved turbulent transport into an additional viscosity.
Reynolds number: A dimensionless ratio comparing inertial forces with viscous forces in a flow. High Reynolds numbers produce broad turbulent scale ranges that make direct resolution costly.

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ThermalRelated: It helps researchers simulate the turbulent flows that organize thermals.