Modeling > Modeling Turbulence > Using Large Eddy Simulation > Formulation > Anisotropic Pseudo Turbulence Velocity Field

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Anisotropic Pseudo Turbulence Velocity Field

Smirnov et al.[16] further modified Kraichnan's [15] method to allow anisotropic turbulent velocity fluctuations to be specified. In this case, the local Reynolds stress tensor, is specified together with the local length scale, .

Before applying the spectrum of random numbers, the local Reynolds stress tensor is rotated into its principal coordinates, to obtain a diagonal tensor . The wave number sequence, , is modified as follows:

(145)

where , and are the components of the vector and , and are the diagonal components of .

The spectrum is then applied as follows to obtain an intermediate field of velocity fluctuations:

(146)

where , , , , , and are defined as with the isotropic field.

This intermediate field, termed is then scaled as follows:

(147)

where , and are the components of .

Finally, the field of velocity fluctuations, , is obtained by rotating from the principal coordinates of back into flow field's coordinates.

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