Bulletin 116, September 2018

Introduction:

The Theme issue (116, September 2018) provides some examples of recent developments in methodological aspects and validation of large-eddy simulation (LES). The increasing complexity of the simulated problems and the use of LES in an engineering context bring new challenges, which concern numerical methods, physical modeling and validation.

As for numerical aspects, the development of highly accurate methods, being at the same time able to deal with complex geometries and robust enough for high Reynolds number flows, appears very attractive in the framework of the application of LES to industrial/engineering problems. These issues were raised in the contributions by Peiró et al., Lodato and Chapelier and Bassi et al. 

On the other hand, in spite of the past intensive research activity and of the related achievements, SGS modeling remains one of the key issue in LES, especially because of the increasing complexity and variety of applications. New achievements in the development of SGS models were presented by Verstappen, Pozorski, Breuer and Hoppe.
A key issue in the perspective of a routine use of LES for engineering applications is also validation. For LES this task is complicated by the fact that in most cases discretization errors and modeling errors have they same order and they may interact in a non obvious manner. Moreover, systematic sensitivity analyses to simulation parameters are difficult because of the large computational costs of each single LES. An example of validation of LES results through the comparison with other contributions to a benchmark and a systematic sensitivity analyses to numerical and modeling error was presented by Salvetti et al.

Table of Contents: 

Thematic Issue on Large-Eddy Simulation: Preface
M. V. Salvetti

Spectral/hp Element Methods for Under-Resolved DNS: Paving the way to Industry-Relevant Simulations
J. Peiro, D. Moxey, M. Turner, G. Mengaldo, R. C. Moura, A. Jassim, M. Taylor and S. J. Sherwin

A Dynamic Sub-Grid Scale Modelling Approach for Discontinuous Finite Elements Methods
G. Lodato and J-B. Chapelier

A Wall-Distance-Free Composite RANS-LES Model Implemented in a Discontinuous Galerkin Solver
F. Bassi, A. Colombo, A. Ghidoni and G. Noventa

On Closing Large-Eddy Simulations 26
R. Verstappen

Subfilter Effects in LES of Particle-Laden Flows: an Overview of Modelling Approaches
J. Pozorski

A. Langevin Subgrid-Scale Model for the Prediction of Turbulent Disperse Multiphase Flows
M. Breuer and F. Hoppe

Reliability of LES Results: a Puzzling Example
M. V. Salvetti, A. Mariotti, L. Siconolfi and C. Mannini