For the incompressible solver you should definitely include the dealiasing flag, namely,

<I PROPERTY="SpectralhpDealiasing" VALUE="True" />

inside section <SOLVERINFO> of your XML file.

Please refer to Sec 2.4.1.2 of Spencer's book (Spectral/hp element methods for computational fluid dynamics) for an explanation about the dealiasing strategy used by the incompressible solver.

Note however the following. The success of our implicit LES approach via high-order CG methods (both in terms of discretization robustness and solution quality) is closely connect to a sensible use of SVV (spectral vanishing viscosity). This requires good knowledge of turbulence physics and of LES-like approaches and takes some programming expertise in Nektar++ since currently we do not have full control of the SVV operator only through the XML file. What I mean is that, for the purpose of implicit LES, you might need to modify the SVV operator inside Nektar and this is a somewhat advanced topic not covered by the user guide, as the CG+SVV-based implicit LES is a modern approach and not yet fully mature.

Please note the following study that discusses the behaviour of different SVV operators from a perspective of under-resolved turbulence computations:

Cheers,

Rodrigo

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