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15 mins
"A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales"
Amirreza Rouhi, Ugo Piomelli, Bernard Geurts
Session: Large Eddy Simulation 2
Session starts: Thursday 27 August, 15:00
Presentation starts: 16:15
Room: Room E

Amirreza Rouhi (Queen's University, Kingston, ON, Canada)
Ugo Piomelli (Queen's University, Kingston, ON, Canada)
Bernard Geurts (University of Twente, Enschede, The Netherlands)

We propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy.