Synthetic turbulence

Generation of synthetic turbulence

The generation of appropriate unsteady inflow conditions currently represents one of the most delicate passage in the setup of CFD simulations for Wind Engineering applications. In particular, turbulent fluctuations found in numerical simulations should be compatible with the ones expected on site.

Currently, there is no technique for the generation of synthetic turbulence which can be considered fully satisfactory and research is still needed on the subject. In fact, not only it is necessary to generate velocity fluctuations characterised by appropriate features but it is also necessary to ensure that such fluctuations are correctly transmitted from the inflow boundary to the computational domain. The problem appears to be particularly delicate especially if inhomogeneous anisotropic turbulence is considered as it is needed when structures immersed in the Atmospheric Boundary Layer, ABL, are considered. Currently, some of the most successful methods are based on the synthetic generation of vortical structures such as [1,2]. Lately, a new method called PRFG3 has been developed al LAMC [3].

The method is based on the discretization of the three-dimensional spectrum of the velocity field, it respects both the divergence-free condition and Taylor assumption and allows to impose the three turbulence intensities as well as approximate all nine integral length scales. Visit our download page for a Matlab implementation of PRFG3.

The picture provides a qualitative view of the turbulent structures which populate the ABL highlighting the importance of a correct generation of the inflow conditions for Computational Wind Engineering analyses.


[1] N. Kornev and E. Hassel, "Method of random spots for generation of synthetic inhomogeneous turbulent fields with prescribed autocorrelation functions" Communications in Numerical Methods in Engineering, 23, 35-43, 2007.

[2] R. Poletto, T. Craft, and A. Revell, "A new divergence free synthetic eddy method for the reproduction of inlet flow conditions for LES," Int Jou Heat Fluid Flow, 91, 519-539, 2013.

[3] L. Patruno, M. Ricci, "A systematic approach to the generation of synthetic turbulence using spectral methods", Comp Meth App Mech Eng, 340, 881-904, 2018.