After several years of planning, the 1st International Workshop on High-Order CFD Methods was successfully held in Nashville, Tennessee, on January 7-8, 2012, just before the 50th Aerospace Sciences Meeting. The American Institute of Aeronautics and Astronautics, the Air Force Office of Scientific Research, and the German Aerospace Center provided much needed support, financial and moral. Over 70 participants from all over the world across the research spectrum of academia, government labs, and private industry attended the workshop. Many exciting results were presented. In this review article, the main motivation and major findings from the workshop are described. Pacing items requiring further effort are presented. © 2013 John Wiley & Sons, Ltd.

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High-order CFD methods: Current status and perspective

Large-eddy simulation: Past, present and the future

\n High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.

Review of research on high-speed railway aerodynamics in China

Computation of unsteady turbomachinery flows: Part 2—LES and hybrids

High-fidelity simulations are employed to study the effect of eight localized arc filament plasma actuators placed around the periphery of a Mach 1.3 converging-diverging nozzle exit. Emphasis is placed on understanding the coherent structures generated by axisymmetric (m = 0), flapping or first mixed (m = ±1) and second mixed (m = ±2) modes, which are excited at the jet column-mode frequency corresponding to a Strouhal number based on jet diameter of 0.3. Baseline (no control) and constant excitation (actuators on continuously) cases are also simulated. Comparisons with experimental results indicate that the computational model reproduces the main features induced by the actuators. Furthermore, the mean flow exhibits many similarities with the theoretical predictions of Cohen and Wygnanski [J. Fluid Mech. 176, 221 (1987)]. Overall, the results indicate a complex coherent structure generation, evolution, and disintegration process. For m = ±1, the phase-averaged flow reveals successive distorted elliptic vortex rings with axes in the flapping plane but alternating on either side of the jet axis. This generates a chain of structures each of which interacts with its predecessor on one side of the major plane and its successor on the other. Through self and mutual induction, the leading segment of each loop is pinched and passes through the previous ring before rapidly breaking up. The m = ±2 mode yields elliptic structures with major axes of successive rings being aligned with the two symmetry planes, which are orthogonal to each other. The minor axis side is pulled downstream faster than the rest of the structure because of the higher velocity near the jet centerline and self-induced effects, yielding a horse-shoe shape when viewed in profile. The m = 0 mode exhibits axisymmetric roll-up events, with vortex ribs in the braid regions connecting successive large coherent structures. The constant excitation (with largest energy input) and baseline cases are similar to each other, indicating that the direct effect of heating is negligible.

Coherent structures in plasma-actuator controlled supersonic jets: Axisymmetric and mixed azimuthal modes

Preface Part I. Introduction: 1. The importance of acoustic research Thomas Huettl 2. Introduction to computational aeroacoustics Manuel Kessler 3. State of the art: LES for acoustics Claus Wagner, Oliver Fleig and Thomas Huettl Part II. Theoretical Background: Aeroacoustics Avraham Hirschberg and Sjoerd Rienstra Part III. Theoretical Background: Large-Eddy Simulation Pierre Sagaut Part IV. Use of Hybrid RANS/LES for Acoustic-Source Predictions Paul Batten, Philippe Spalart and Marc Terracol Part V. Numerical Methods: 4. Spatial and temporal discretization schemes Tim Broeckhoven, Jan Ramboer, Sergey Smirnov and Chris Lacor 5. Boundary conditions for LES Michael Breuer 6. Boundary conditions: acoustics Fang Q. Hu 7. Some concepts of LES-CAA coupling Wolfgang Schroder and Roland Ewert Part VI. Applications and Results of Large-Eddy Simulations for Acoustics: 8. Plane and axisymmetric mixing layers Christophe Bogey and Christophe Bailly 9. Far-field jet acoustics Daniel J. Bodony and Sanjiva K. Lele 10. Cavity noise Xavier Gloerfelt, Christophe Bogey and Christophe Bailly 11. Aero-elastic noise Sandrine Vergne, Jean-Marc Auger, Fred Perie, Andre Jacques and Dimitri Nicolopoulos 12. Trailing edge noise Roland Ewert and Eric Manoha 13. Blunt bodies (cylinder, cars) Franco Magagnato 14. Internal flows Philippe Lafon, Fabien Crouzet and Jean Paul Devos 15. Industrial aeroacoustics analyses Fred Mendonca Part VII. Conclusions Claus Wagner, Pierre Sagaut and Thomas Huettl.

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Large-eddy simulation for acoustics

Large-Eddy Simulation for Acoustics: Contributors

Recently, direct numerical simulations of turbulent flow in helically coiled pipes have been performed and published. Here, computational results are shown for low Reynolds number flow (Re τ = 230) through one helical pipe configuration (curvature κR = 0.1, torsion rR = 0.165). The results are shortly discussed and further information of other toroidal or helical pipe flow simulations are given. Besides, the Reynolds-stress balance equations derived in orthogonal helical coordinates are presented to allow further insight into helical pipe flow. The Reynolds-stress balance equations are of great importance for turbulence modelling. Compared to their formulation in cylindrical coordinates, further terms occur, describing centrifugal and other inertia force effects which result from pipe curvature and torsion. Except for toroidal flow, where torsion is zero and a symmetry plane exists, no possibility to simplify the equations has been found.

Thomas Hüttl

Papers

Large-eddy simulation for acoustics

Large-Eddy Simulation for Acoustics: Contributors

Reynolds‐stress balance equations in orthogonal helical coordinates and application

Use of Hybrid RANS–LES for Acoustic Source Predictions

Large-Eddy Simulations for Acoustics