83 Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM) Editors E. H. HirschellMiinchen K. Fujii/Kanagawa w. Haase/Miinchen B. van Leer/Ann Arbor M. A. Leschziner/London M. Pandolfi/Torino J. Periaux/Paris A. Rizzi/Stockholm B. Roux/Marseille Springer-Verlag Berlin Heidelberg GmbH ONLINE LIBRARY Engineering http://www.springer.de/engine/ LESFOIL: Large Eddy Simulation of Flow Around a High Lift Airfoil Results of the Project LESFOIL Supported by the European Union 1998 - 2001 Lars Davidson, Davor Cokljat, Jochen Frohlich, Michael A. Leschziner, Chris Mellen and Wolfgang Rodi (Editors) Springer Prof. Dr. Lars Davidson Dr. Jochen Frohlich (coordinator) Dr. Chris Mellen Dept. of Thermo and Fluid Dynamics Prof. Dr. Wolfgang Rodi Chalmers University of Technology Institute for Hydromechanics SE-412 96 Gothenburg, Sweden Universitat Karlsruhe Kaiserstr. 12 Dr. Davor Cokljat D -76128 Karlsruhe, Germany Fluent Europe Ltd. Sheffield Airport Business Park Prof. Dr. Michael A. Leschziner Europa Link Imperial College of Science Sheffield S9 1XU, Great Britain Technology and Medicine Aeronautics Department Prince Consort Rd. London SW7 2BY, Great Britain ISBN 978-3-642-05605-5 ISBN 978-3-540-36457-3 (eBook) DOI 10.1007/978-3-540-36457-3 Library of Congress Cataloging·in-Publication-Data LESFO[L : large eddy simulation of flow around a high lift airfoil: results of the Project LESFO[L supported by the European Union 1998 -2001 I Lars Davidson ... let al.l editors. p. cm. -- (Notes on numerical fluid mechanics and multidisciplinary design; 83) Includes bibliographical references. I. Aerofoils. 2. Lift (Aerodynamics)--Research--Europe. 3. Project LESFO[L European Commission) I. Davidson, Lars. [I. Series. TL574.A4L472003 629.134'32--dc21 This work is subject to copyright. 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Violations are liable for prosecution under the German Copyright Law. http://www.springer.de © Springer-Verlag Berlin Heidelberg 2003 Originally published by Springer-Verlag Berlin Heidelberg in 2003 Softcover reprint of the hardcover 1st edition 2003 The use of general descriptive names, registered names trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik Berlin Printed on acid free paper 62/3020/M -543 2 1 0 NNFM Editor Addresses Prof. Dr. Ernst Heinrich Hirschel Prof. Dr. Maurizio Pandolfi (General editor) Politecnico di Torino Herzog-Heinrich-Weg 6 Dipartimento di Ingegneria D-85604 Zorneding Aeronautica e 5paziale Germany Corso Duca degli Abruzzi, 24 E-mail: [email protected] 1- 10129 Torino Italy prof. Dr. Kozo Fujii E-mail: [email protected] Space Transportation Research Division Prof. Dr. Jacques Periaux The Institute of Space Dassault Aviation and Astronautical Science 78, Quai Marcel Dassault 3-1-1, Yoshinodai, 5agamihara, F-92552 5t. Cloud Cedex Kanagawa, 229-8510 France Japan E-mail: [email protected] E-mail: [email protected] Prof. Dr. Arthur Rizzi Dr. Werner Haase Department of Aeronautics Hohenkirchener 5tr. 19d KTH Royal Institute of Technology D-85662 Hohenbrunn Teknikringen 8 Germany S-10044 Stockholm E-mail: [email protected] Sweden E-mail: [email protected] Prof. Dr. Bram van Leer Department of Aerospace Engineering Dr. Bernard Roux The University of Michigan L3M - 1MT La Jetee Ann Arbor, MI 48109-2140 Technopole de Chateau-Gombert USA F-13451 Marseille Cedex 20 E-mail: [email protected] France E-mail: [email protected] prof. Dr. Michael A. Leschziner Imperial College of Science, Technology and Medicine Aeronautics Department Prince Consort Road London SW7 2BY UK. E-mail: [email protected] FOREWORD Large Eddy Simulation is a relatively new and still evolving computatio nal strategy for predicting turbulent flows. It is now widely used in research to elucidate fundamental interactions in physics of turbulence, to predict phe nomena which are closely linked to the unsteady features of turbulence and to create data bases against which statistical closure models can be asses sed. However, its applicability to complex industrial flows, to which statisti cal models are applied routinely, has not been established with any degree of confidence. There is, in particular, a question mark against the prospect of LES becoming an economically tenable alternative to Reynolds-averaged N avier-Stokes methods at practically high Reynolds numbers and in complex geometries. Aerospace flows pose particularly challenging problems to LES, because of the high Reynolds numbers involved, the need to resolve accura tely small-scale features in the thin and often transitional boundary layers developing on aerodynamic surfaces. When the flow also contains a separated region - due to high incidence, say - the range and disparity of the influen tial scales to be resolved is enormous, and this substantially aggravates the problems of resolution and cost. It is just this combination of circumstances that has been at the heart of the project LESFOIL to which this book is devoted. The project combined the efforts, resources and expertise of 9 partner organisations, 4 universities, 3 industrial companies and 2 research institu tes. These partners collaborated closely over a period of 3 years, addressing a wide range of issues, both numerical and physical, in an effort to answer the question posed above in relation to the utility of LES for airfoil flows. Hundreds of simulations were undertaken, many hours of sometimes heated discussion took place and many weeks have been devoted to poring over re sults, understanding their implications and removing inconsistencies through repeated simulations and critical inquiry. For the large majority of researchers involved, LESFOIL has been a rewarding and fruitful experience, well-worth the effort and expense. The LESFOIL activities were co-funded by the Fourth Research Framework Programme of the European Union (EU). All partners deserve recognition and gratitude for their commitment, hard work and willingness to share their knowledge and experience. Special appre ciation must be given to the European Commission, notably to Dr. Dietrich Kn6rzer, for recognising that a still speculative, somewhat fundamental stra tegy deserves to be promoted and funded alongside the usual industrially oriented projects which are the backbone of the EU's R&D programme. Finally, the editors would like to thank Prof. E.H. Hirschel, General Editor of the Springer Series Notes on Numerical Fluid Mechanics', who made it possible to publish the outcome of LESFOIL in the present book. Maj 2002 LD, DC, JF, MAL, CPM, WR Table of Contents I. INTRODUCTION... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 II. PREPARATORY WORK.. .. .. .. .. .. .. .. .. .. .. .. 7 1 Task 1: Subgrid models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.1 Summary of work progress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2 Task 1.1: Grid generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Unstructured grids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Structured C-grids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3 Task 1.2: Generation of database with DNS . . . . . . . . . . . . . . . . 11 1.4 Task 1.3: Development and evaluation of subgrid models in simple configurations ................................... 11 Evaluated subgrid-scale models. . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.5 Conclusion............................................ 20 2 Task 2: Near-wall models .................................... 22 2.1 Introduction........................................... 22 2.2 Overview of Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.3 Chalmers.............................................. 25 The Hybrid LES-RANS model. .......................... 26 2.4 CERFACS............................................. 30 2.5 University of Karlsruhe ................................. 33 2.6 UMIST/QMW......................................... 42 2.7 Conclusions and Overall assessment. . . . . . . . . . . . . . . . . . . . . . 53 3 Task 4: Numerical methods .................................. 58 3.1 Introduction........................................... 58 3.2 Contribution by Chalmers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Performance Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Speed-up. ............................................. 59 Deferred correction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 PISO and SIMPLEC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Spatial Discretisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3.3 Contribution by Fluent ................................. 61 Performance Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Discretization Scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Accuracy assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Velocity Profiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.4 Contribution by University of Karlsruhe. . . . . . . . . . . . . . . . . . . 65 Fourier solver for the pi equation. ........................ 65 Implications of 2D /3D Zonal refinement method on Fourier solver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.5 Contribution by ONERA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 3.6 Contribution by University of Surrey. . . . . . . . . . . . . . . . . . . . . . 68 3.7 Contribution by UMIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Solution of momentum equations. ........................ 69 Time-step control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 The pressure equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Domain decomposition and parallelization. ................ 70 Partial diagonalisation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Multigrid algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Performance Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.8 Achievements and recommendations ..................... 71 III. THE AIRFOIL INVESTIGATIONS. . . . . . . . . . . 73 4 Task 5: Airfoil Computations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.1 Introduction........................................... 75 The Principal Airfoil Geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Common Mesh. ........................................ 77 4.2 Contribution by Chalmers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Numerical Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Boundary Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Convergence Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Computations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 4.3 Contribution by Alenia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Numerical method. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Turbulence models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Steady flow computations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Unsteady RANS computations. .......................... 101 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 103 Recommendations for future work.. . . . . . . . . . . . . . . . . . . . . . .. 103 4.4 Contribution by CERFACS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 105 Introduction. .......................................... 105 Numerical schemes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 106 Wall functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 107 Airfoil Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 107 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 118 4.5 Contribution by Dassault-Aviation ....................... 119 Description of the Na vier-Stokes code. .................... 119 Towards LES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 122 Application to the A-airfoil. ............................. 124 Comparison of LES results using different SGS models. . . . . .. 126 Comparison between RANS and LES. . . . . . . . . . . . . . . . . . . . .. 130 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 133 4.6 Contribution by FLUENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 135 x Introduction. .......................................... 135 Model Description. ..................................... 135 The Mesh. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 137 Numerical Details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 139 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 140 Conclusions ................................ " . . .. . . . . .. 147 4.7 Contribution by University of Karlsruhe. . . . . . . . . . . . . . . . . .. 148 LES resolution requirements. ............................ 148 Computational Efficiency. ............................... 149 Transition modelling. ................................... 150 Airfoil calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 154 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165 4.8 Contribution by ONERA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 167 Introduction. .......................................... 167 Simulation method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 167 Subgrid Scale Modelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 167 Euler Flux Discretization. ............................... 168 2D /3D coupling method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 169 Computational Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 170 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 173 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 182 4.9 Contribution by QMW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 184 Overview. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 184 The Numerical Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 187 Simulations and Results. ................................ 190 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 198 IV. LESSONS LEARNED ........................... 201 5 Synthesis of the Airfoil Flow Simulations. . . . . . . . . . . . . . . . . . . . . .. 203 5.1 Common Mesh Comparisons. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 203 5.2 Trailing edge geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 207 5.3 Final Results Comparisons .............................. 208 5.4 Subgrid-Scale Modelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 216 5.5 Near-Wall modelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 217 5.6 Transition Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 219 5.7 Synthesis conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 220 V. CONCLUSIONS AND OUTLOOK ............. 223 VI. REFERENCES ................................... 233 VII. ADDRESSES OF PARTNERS ................ 241 XI I. INTRODUCTION