### 2.6.5. Boundary Conditions

For LES simulations, unsteady fluctuations have to be specified in most cases at the inlet boundaries. This greatly complicates the use of LES in industrial flows, as the details of these fluctuations are generally not known. In DES simulations, it is in most cases possible to specify the same boundary conditions as for the SST model. This is particularly true if the default setting of the zonal model are used ([55]).

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