In a recent JFM article titled On the role of eddy viscosity in resolvent analysis of turbulent jets, FELiCS is used to quantify how eddy-viscosity modelling affects linearized mean-flow analysis of broadband turbulent jets.
By combining SPOD, resolvent analysis and analyzing coherent-structure energy budgets, the study shows that coherent Reynolds stresses have a predominantly dissipative effect. It is demonstrated that this nonlinear dissipation must be represented explicitly in the linear operator to obtain accurate resolvent modes, rather than being absorbed into the resolvent optimal forcing as is often assumed. A systematic comparison of predictive and data-driven eddy-viscosity fields demonstrates that a Boussinesq-type eddy viscosity can successfully model this nonlinear energy transfer. The energetic considerations reveal that the role of eddy viscosity is to ensure that the energy the structures receive from the mean flow is dissipated.
To build the linearized operators and perform the resolvent analysis for various eddy-viscosity fields, FELiCS proved to be the ideal software framework.