Ernst Heinrich Hirschel

Navier–Stokes solvers in European aircraft design

The paper gives a broad perspective of the progress made during the last 10 years in solving the Navier-Stokes equations and traces how this simulation technique went from being a specialized research topic to a practical engineering tool that design engineers use on a routine basis. The scope is limited to Navier-Stokes solvers applied to industrial design of airframes with attention focused particularly on developments in Europe. An overview of the different Navier-Stokes codes used in Europe is given, and on-going developments are outlined. The current state of progress is illustrated by computed steady and unsteady solutions to industrial problems, ranging from airfoil characteristics, flow around an isolated wing, to full aircraft configurations. A discussion on the future industrial design environment is given, and developments in Europe towards a more integrated design approach with underlying concepts like concurrent engineering (CE) and the virtual product (VP) are summarized. The paper concludes with a discussion on future challenging applications.

Basics of aerothermodynamics

The Flight Environment.- The Thermal State of the Surface.- Transport for Momentum, Energy and Mass.- Real-Gas Aerothermodynamic Phenomena.- Inviscid Aerothermodynamic Phenomena.- Attached High-Speed Viscous Flow.- Laminar-Turbulent Transition and Turbulence in High-Speed Viscous Flow.- Strong Interaction Phenomena.- Simulation Means.- The RHPM-Flyer.- Governing Equations for Flow in General Coordinates.- Constants, Functions, Dimensions and Conversions.- Symbols.

Numerical solutions of the Euler equations for steady flow problems

Keywords: Euler : equation d ; ecoulement : stationnaire ; modeles : mathematiques Reference Record created on 2005-11-18, modified on 2016-08-08

Issues of Multidisciplinary Design

Issues of multidisciplinary design are considered in view of the aerodynamical and structural design of the airframe, i. e. fuselage, wing, and tail unit. Background problems, like Cayley’s design paradigm are discussed, as well as ideal-typical airframe definition and development phases, and the industrial challenges which numerical multidisciplinary design and optimization (MDSO) poses. Finally the state of the art of MDSO methods is illustrated.

100 Volumes of `Notes on Numerical Fluid Mechanics'

This volume contains 37 invited contributions, collected to celebrate one hundred volumes of the NNFM Series. After a general introduction overviews are given in five parts of the developments in numerical fluid mechanics and related fields. In the first part information about the series is given, its origins are discussed, as well as its environment and the German and European high-performance computer scene. In Part II the co-editors of the series give short surveys over developments in their countries. Current applications, mainly in the aerospace sector, but also in the automotive sector, are discussed in Part III. Applications to flow problems in engineering and physics, ranging from hydraulic machinery to astrophysics, are the topics of Part IV. Algorithms, computer science, commercial CFD, public partnerships in high-performance computing, and hardware development up to petaflops computers are treated in Part V. All volumes, which were published in the series finally are listed in Part VI.

Convergence to Steady State

The time-dependent formulation is most often used to compute steady state solutions to the Euler equations. There are several mechanisms that drive the solution to a steady state. Here we shall concentrate on the dissipation effect due to the boundary conditions, and not to the effect of artificial viscosity. Therefore we shall study hyperbolic partial differential equations where the boundary effects are dominant. The results are also valid for more general classes of differential equations of essentially hyperbolic character, as for example the Navier-Stokes equations for high Reynolds numbers. The study is mathematical, much of it repeated from Ref. 1.

Modelling of Vortex Flows: Vorticity in Euler Solutions

In Chapter IX it was stated that wakes, respectively vortex sheets, and vortices can be handled in the frame of inviscid theory. This is done for a long time already in the frame of potential wing theory (see for instance Ref. 1). Panel methods, as discrete potential methods, can be seen as extension and generalization of — linear — potential wing theory to general and complicated aircraft geometries at subsonic and even supersonic speeds (see e.g. Ref. 2). With proper vortex sheet paneling, panel methods can also be employed on delta wings with leading-edge vortices, in this way allowing to compute non-linear lift problems with — linear — potential wing theory (see e.g. Ref. 3).

General Developments of Numerical Fluid Mechanics Until the Middle of the 20th Century

Today’s computational methods are built upon physical and numerical models. Thus it is important to have an appreciation of the reasoning and thought processes that established our current understanding of the mechanics of fluids, all put in place before the age of numerical solutions. A brief sketch is given of the evolution of the ideas that led to the formulation of the equations governing fluid flow, the problems to which the equations were applied, and the efforts to solve them before computers were available. After the historical origins of the fluid-flow models are in place, the last section traces the transition undergone during the 20th Century, starting with analytical means to solve the mathematical problems that successively evolved into numerical approaches to solving them, thus leading up to the present time of the computational era.

The NNFM Series

The book series “Notes on Numerical Fluid Mechanics and Multidisciplinary Design” is portrayed. It originally was conceived as publication organ of the GAMM-Committee for Numerical Methods in Fluid Mechanics, but soon its scope was extended. In three sections it is sketched how the series came into being, how its aim developed, and how it evolved from the first to the present volume. The general editors and the co-editors of the series are listed and their duties are outlined. Finally acknowledgements are expressed to the publishing houses of the series, first Vieweg, then the Springer-Verlag, and especially to the persons directly involved in the publication of the series.

The Origin of the Series in the GAMM-Committee for Numerical Methods in Fluid Mechanics

The NNFM series originated as publication organ of the GAMMCommittee for Numerical Methods in Fluid Mechanics. This committee was founded in (West-) Germany in 1974 and existed until 1992. Its development and the main activities - the organization of GAMM-Workshops and GAMMConferences on Numerical Methods in Fluid Mechanics - are sketched in this contribution.