Turbulence modelling (LES)

Large Eddy Simulation (LES) is a turbulence modeling approach that allows to predict the behavior of turbulent flows using less resources than DNS.

It is based on spacial filtering of the Navier-Stokes equation, so from a computational point of view is similar to DNS, in the sense that the LES equations also have to be time-accurate integrated during a period of time and then averaged to obtain the result of interest.

CTTC and its spin-off company Termo Fluids S.L. have developed parallel codes for LES in both structured and unstructured meshes.

The following example is the simulation of the airflow in a single family house HVAC, at Reynolds number 13.000.

The dimensions of the house are 8 x 14 x 3 meters, and the air is changed once per hour. The LES model used was Yoshizawa, with a 2.12 million control volumes mesh.

The models used in the previous study are validated against benchmark cases, such as the Differentially Heated Cavity (DHC), shown in the next figure. The video shows a DNS simulation of a DHC with Rayleigh number of 10^11 using 111 million control volumes. These kind of simulations can be used to evaluate the LES models, in order to validate them.

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