Christer Fureby

From canonical to complex flows: Recent progress on monotonically integrated LES

Large-eddy simulation (LES) based on subgrid-scale modeling implicitly provided by the discretization algorithm has been the subject of considerable recent interest. In the monotonically integrated LES approach, flux-limiting schemes emulate the flow features in the high-wavenumber end of the inertial range region of turbulence.

On grid resolution requirements for LES of wall-bounded flows

Grid requirements for LES of wall-bounded flows are considered. The setting is a zero pressure gradient turbulent boundary layer on a flat plate, but the results are intended to be of use generally for the simulation of flows with an important influence of turbulent boundary layers. The basis for the grid estimates are expressions for the thickness and the viscous length scale of a turbulent boundary layer. The literature is reviewed, and a new power law is proposed, the coefficients of which have been determined using recent high-Re experimental data. An estimation for the number of grid points required for NWM-LES is derived, which is more general than previously published such estimates. A complete simulation methodology, including a numerical tripping device for transition to turbulence in the boundary layer, is demonstrated for NWM-LES of a flat plate turbulent boundary layer. The predictive accuracy is assessed by comparison with DNS data.

Vortex-Shedding Induced Trailing-Edge Acoustics

The operational requirements for naval vessels have seen an increasing demand for quieter ships, and hence the management of the ship’s hydrodynamic signature requires improved predictions of flow induced noise and particularly propeller noise. Studies involving model-scale and full-scale ships are complicated and expensive, and in order to better understand the detailed physics and to develop better prediction models, simpler problems can be useful. In this work we consider the flow and flow induced noise from the trailing edge of a flat airfoil with a 45° asymmetrically beveled trailing edge and an elliptical leading edge. For the airfoil under consideration simultaneous flow and noise measurements from the University of Notre Dame are available for comparison with computational flow and acoustic models, making this a rather unique validation test case. Here we use Detached Eddy Simulation (DES), Large Eddy Simulation (LES) and Implicit LES (ILES) methods coupled to an acoustic model for the density (or pressure) perturbations similar to the standard Ffowcs-Williams & Hawkings or Lighthill-Curles models. The comparison with the experimental data shows that both the flow and the acoustics are reasonably well predicted by all three models, but with the LES model resulting in somewhat more accurate flow and acoustic predictions.

Combustion in Afterburning Behind Explosive Blasts

Ekaterina Fedina, K. C. Gottiparthi, Christer Fureby and Suresh Menon 1 Defence & Security Systems and Technology, Swedish Defence Research Agency – FOI, 147 25 Stockholm, Sweden, ekaterina.fedina@foi.se 2 School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, USA, kalyan.gottiparthi@gatech.edu 3 Defence & Security Systems and Technology, Swedish Defence Research Agency – FOI, 147 25 Stockholm, Sweden, fureby@foi.se 4 School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, USA, suresh.menon@ae.gatech.edu