Stefan Fechter

Room 0.032
Institute of Aerodynamics and Gas Dynamics
Pfaffenwaldring 21
70569 Stuttgart
Germany

Tel.: +49 (0)711 685-60224
Email

Research topics

  • Discontinuous Galerkin (DG) methods for compressible multiphase flows at extreme ambient conditions (e.g. at the critical point)
  • Realistic equation of states for the description of multi-phase flows at sub- and super-critical conditions
  • Resolution of interface related phenomena like surface tension and phase transition by generalized Riemann problems
  • Project A2  (“Development of numerical methods for the simulation of  compressible droplet dynamic processes at extreme ambient conditions”) within collaborative research council SFB-TRR75
  • Direct numerical simulation
  • Aeroacoustics
  • High performance computing (HPC)

Research description

In many technical applications, multi-phase flows meet conditions such as high pressure environments and/or high velocities that prohibit the popular assumption of incompressibility. Important examples for such extreme ambient conditions include fuel injection systems of aeronautical, automotive and rocket engines that operate at high-pressure and/or high-temperature conditions. In contrast to the incompressible treatment, that is typically found in two-phase numerical solvers in practical use today, all conservation equations are coupled via the equation of state and have to be solved simultaneously. The decomposition and separate solution of hydrodynamics and thermodynamics as in the incompressible case is no longer possible. Hence, the numerical simulation of compressible multi-phase flow introduces additional difficulties to the numerical approach mainly due to the necessary consistent approximation of thermodynamics and the large density and pressure jumps.

In the last years the focus of the research was on the development of consistent numerical methods for the resolution of the phase interface in the computational domain. We focused on the sharp interface resolution of the interface. At the interface the jump conditions are provided by the solution of a generalized Riemann problem. This interface Riemann solution resolved local interface effects due to the coupling of different phases, surface tension and phase transition. Exact and approximative solvers have been developed for this case. For cases including phase transition effects this results in a mixed hyperbolic-elliptic problem. Hence, special considerations for the resolution of the interface Riemann problem have to be taken.

The numerical method is based on the discontinuous Galerkin spectral element method with a sub-cell finite volume refinement in the vicinity of the phase interface. This approach is done to enlarge the interface resolution that is implemented by means of generalized Riemann problems at the grid cell boundaries. The interface tracking is based on the level-set method extended for a compressible flow field. The high-order level-set descriptions mimics numerical diffusion problems and allows the accurate resolution of the interface curvature and normals. The accuracy of these quantities can be enlarged by a a-posteriori reconstruction of the level-set polynomial.

 

Presentations

2015

Stefan Fechter

Simulation of compressible multi-phase flows at extreme ambient conditions (PhD defence) Presentation

01.07.2015.

BibTeX | Links:

2014

Stefan Fechter at ICNMMF-II conference, Darmstadt, Germany

Simulation of compressible multi-phase flows using a Discontinuous Galerkin Method and realistic equations of state Presentation

02.07.2014.

BibTeX | Links:

2013

Stefan Fechter at ICMF 2013 conference, Jeju, South Korea

Interface coupling based on a Discontinuous Galerkin multi-scale method for compressible multiphase flow Presentation

Jeju, South Korea, 29.05.2013.

Abstract | BibTeX | Links:

2012

Stefan Fechter at workshop "Numerical Methods for Two-phase Flow" in Stuttgart

A discontinuous Galerkin based multiscale solver for compressible two-phase flows Presentation

29.11.2012.

BibTeX | Links:

Stefan Fechter at ICCFD 7 Conference in Kona, Hawaii

A discontinuous Galerkin based multiscale method for compressible multiphase flow Presentation

11.07.2012.

Abstract | BibTeX | Links:

Publications

2017

Stefan Fechter; Timon Hitz; Fabian Föll; Claus-Dieter Munz

Comparison of Subcritical Interface Approximations at High Temperature and Pressure Conditions Inproceedings

53rd AIAA/SAE/ASEE Joint Propulsion Conference, AIAA Propulsion and Energy Forum, 2017.

Links | BibTeX

Stefan Fechter; Sebastian Karl; Volker Hannemann; Klaus Hannemann

Simulation of LOx/GH2 single coaxial injector at high pressure conditions Inproceedings

53rd AIAA/SAE/ASEE Joint Propulsion Conference, pp. 4765, 2017.

Links | BibTeX

Fechter, Stefan; Munz, Claus-Dieter; Rohde, Christian; Zeiler, Christoph

Approximate Riemann solver for compressible liquid vapor flow with phase transition and surface tension Journal Article Forthcoming

Computers & Fluids, Forthcoming.

Links | BibTeX

Stefan Fechter; Claus-Dieter Munz; Christian Rohde; Christoph Zeiler

A sharp interface method for compressible liquid--vapor flow with phase transition and surface tension Journal Article

Journal of Computational Physics, 336 , pp. 347–374, 2017.

Links | BibTeX

2015

Stefan Fechter; Claus-Dieter Munz

A discontinuous Galerkin based sharp-interface method to simulate three-dimensional compressible two-phase flow Journal Article

International Journal of Numerical Methods in Fluids Journal for Numerical Methods in Fluids, 78 (7), pp. 413-435, 2015, ISSN: 1097-0363.

Links | BibTeX

2014

Stefan Fechter; Christoph Zeiler; Claus-Dieter Munz; Christian Rohde

Simulation of compressible multi-phase flows at extreme ambient conditions using a Discontinuous Galerkin Method Inproceedings

Proceedings of the 26th Annual Conference on Liquid Atomization and Spray Systems (ILASS) 2014, Bremen, Germany, 2014.

BibTeX

Stefan Fechter; Claus-Dieter Munz

A Combined Finite Volume Discontinuous Galerkin Approach for the Sharp-Interface Tracking in Multi-Phase Flow Incollection

Finite Volumes for Complex Applications VII-Elliptic, Parabolic and Hyperbolic Problems, pp. 911–918, Springer, 2014.

BibTeX

2013

Stefan Fechter, Claus-Dieter Munz

Interface coupling based on a Discontinuous Galerkin multi-scale method for compressible multiphase flow Inproceedings

Proceedings of the 8th International Conference on Multiphase Flow ICMF 2013, Jeju, Korea., 2013.

BibTeX

Stefan Fechter; Felxi Jaegle; Veronika Schleper

Exact and approximate Riemann solvers at phase boundaries Journal Article

Computers & Fluids, 75 (0), pp. 112-126, 2013, ISSN: 0045-7930.

Links | BibTeX

Stefan Fechter; Alexandros Terzis; Peter Ott; Bernhard Weigand; Jens Von Wolfersdorf; Magali Cochet

Experimental and numerical investigation of narrow impingement cooling channels Journal Article

International Journal of Heat and Mass Transfer, 67 , pp. 1208–1219, 2013.

BibTeX

2012

Felix Jaegle, Stefan Fechter, Markus Boger; Claus-Dieter Munz

Direct numerical simulation of compressible multiphase flow using a Discontinuous Galerkin based multiscale approach Inproceedings

Proceedings of the 12th Triennial International Conference on Liquid Atomization and Spray Systems, Heidelberg, Germany., 2012.

BibTeX

Stefan Fechter; Florian Hindenlang; Hannes Frank; Claus-Dieter Munz; Gregor Gassner

Discontinuous Galerkin schemes for the direct numerical simulation of fluid flow and acoustics Inproceedings

42nd AIAA Fluid Dynamics Conference and Exhibit. New Orleans: American Institute of Aeronautics and Astronautics, pp. 2012–2187, 2012.

BibTeX

Stefan Fechter; Felix Jaegle; Markus Boger; Christoph Zeiler; Claus-Dieter Munz; Christian Rohde

A discontinuous Galerkin based multiscale method for compressible multiphase flow Inproceedings

Proceedings of the Seventh International Conference on Computational Fluid Dynamics (ICCFD7), 2012.

BibTeX