A Hybrid Model Based on Continuous Fluctuation Corrections

Maria Vittoria Salvetti (1) , Hilde Ouvrard (2) , Bruno Koobus (2) , Simone Camarri (1) , Alain Dervieux (3)

1 DIA - Dipartimento Ingegneria Aerospaziale "Lucio Lazzarino"
2 Département de Mathématiques [Montpellier]
3 SMASH - Simulation, modeling and analysis of heterogeneous systems

A novel method is proposed for blending RANS and VMS-LES approaches in a hybrid model. To this purpose, the flow variables are decomposed in a RANS part (i.e. the averaged flow field), a correction part that takes into account the turbulent large-scale fluctuations, and a third part made of the unresolved or SGS fluctuations. The basic idea is to solve the RANS equations in the whole computational domain and to correct the obtained averaged flow field by adding, where the grid is adequately refined, the remaining resolved fluctuations. The RANS model is of low-Reynolds K-EPSILON type. To obtain a model which progressively switches from the RANS to the LES mode, a smooth blending function is introduced to damp the correction term. Different definitions of the blending function are proposed and investigated. The capabilities of the proposed hybrid approach are appraised in the simulation of the flow around a circular cylinder at $Re=140000$. Results are compared to those of other hybrid simulations in the literature and to experimental data.

Mots clés: Turbulence; Hybrid RANS/LES approach; bluff-body flows; variational multi-scale; unstructured meshes

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Analyse numérique [math.NA]

Maria Vittoria Salvetti, Hilde Ouvrard, Bruno Koobus, Simone Camarri, Alain Dervieux. A Hybrid Model Based on Continuous Fluctuation Corrections. [Research Report] RR-6564, INRIA. 2008, pp.24. ⟨inria-00289193v2⟩