Large Eddy Simulation—our secret sauce

Behind our high-fidelity simulations for aeroacoustics, aerodynamics, combustion, heat transfer, and multiphase is CharLES—our large eddy simulation (LES) flow solver. CharLES features multi-physics simulation capabilities that can accurately predict some of the most challenging problems in computational fluid dynamics.


Aeroacoustics predictions are relevant for a wide range of industrial applications, from supersonic jets to fan noise to combustion-acoustic interactions in gas turbines. Even for “extremely loud” noises, the pressure fluctuations that constitute the radiated sound are orders of magnitude smaller than the ambient pressure and much smaller than the near-field pressure disturbances associated with turbulent compressible flow.

CharLES is ideally suited to capture such important but low-energetic acoustic features, thanks to its unsteady simulation capabilities with low-dissipation and low-dispersion numerical methods.

Play Video
Simulation of a heated, over-expanded supersonic jet from a faceted military-style nozzle. Read the paper to learn more.


CharLES can predict aerodynamic forces for complex geometries over a range of flow regimes from low-Mach to transonic and supersonic. For example, capture changes in vehicle drag due to subtle geometric design modifications. Or, identify the onset of stall over high angle of attack airfoils on a commercial aircraft.

Play Video
Wall-Modeled Large Eddy Simulation (WMLES) of the JAXA Standard Model in landing configuration. Read the paper to learn more.


Turbulent combustion underpins much of our modern energy economy. Power generation, aviation, aerospace, and automotive technologies all depend on how well we mix reactants, release their energy, and manage their byproducts. Making these processes cleaner, safer, and more efficient is crucial to navigating the future of our planet.

The combustion models in CharLES work seamlessly with its advanced numerics to deliver accurate and cost-effective predictions of turbulent reacting flows. These solutions—along with specialized data processing tools and analytics—enable combustion engineers to understand their current systems better and imagine the next generation of improved combustion technologies.

Play Video
Simulation of turbulent combustion. Read the article to learn more.

Heat Transfer

The accurate prediction of heat transfer can be difficult in turbulent flow, but is critical to the durability of many machines. Accurate heat transfer predictions require careful attention to the local state of the boundary layer, the presence of flow separation and reattachment, and transition to turbulence. The control of boundary layer grid size made possible by Cascade’s Voronoi-based meshing technology, combined with the CharLES solver’s advanced numerical methods and wall modeling, can yield actionable results for absolute heat flux predictions. Conjugate heat transfer is also available with minimal impact on solver speed.  

Conjugate heat transfer predictions of a square jet exhausting over a film cooled deck from the AIAA Propulsion Aerodynamics Workshop. Displayed in this video is the fluid temperature above the deck at increasing blowing ratios (top to bottom). Note the strong interactions of the nozzle exit shear layers with the coolant flow.


Accurate prediction of multiphase flows is significant in a variety of engineering applications such as chemical and paint spraying, oil and gas transportation, coolant systems, and liquid fuel injection in combustion engines. High-fidelity simulations of liquid injectors, for example, can provide detailed unsteady physics of atomization and fuel-air mixing to design or optimize an injector where experiments usually have limited access.

The multiphase model in CharLES is based on the advanced volume-of-fluid method coupled to a Lagrangian spray tracking approach to effectively predict large-scale liquid structures as well as fine-scale droplets and particles for a wide range of flow regimes from low-Mach to supersonic.

Play Video

Simulation of liquid jet atomization from a single injector. Read the paper to learn more.