Thomas Bolemann

• Dipl.-Ing.
• Research Associate at University of Stuttgart

The construction of discontinuous Galerkin (DG) methods for the compressible Euler or Navier-Stokes equations (NSE) includes the approximation of non-linear flux terms in the volume integrals. The terms can lead to aliasing and stability issues in turbulence simulations with moderate Mach numbers (Ma≲0.3), e.g. due to under-resolution of vortical d...

High order (HO) schemes are attractive candidates for the numerical solution of multiscale problems occurring in fluid dynamics and related disciplines. Among the HO discretization variants, discontinuous Galerkin schemes offer a collection of advantageous features which have lead to a strong increase in interest in them and related formulations in...

This work is focused on the entropy analysis of a semi-discrete nodal discontinuous Galerkin spectral element method (DGSEM) on moving meshes for hyperbolic conservation laws. The DGSEM is constructed with a local tensor-product Lagrange-polynomial basis computed from Legendre–Gauss–Lobatto points. Furthermore, the collocation of interpolation and...

The construction of discontinuous Galerkin (DG) methods for the compressible Euler or Navier-Stokes equations (NSE) includes the approximation of non-linear flux terms in the volume integrals. The terms can lead to aliasing and stability issues in turbulence simulations with moderate Mach numbers (Ma < 0.3), e.g. due to under-resolution of vortical...

High order (HO) schemes are attractive candidates for the numerical solution of multiscale problems occurring in fluid dynamics and related disciplines. Among the HO discretization variants, discontinuous Galerkin schemes offer a collection of advantageous features which have lead to a strong increase in interest in them and related formulations in...

This paper summarizes our progress in the application and feature development of a high-order discontinuous Galerkin (DG) method for scale resolving fluid dynamics simulations on the Cray XC40 Hazel Hen cluster at HLRS. We present the extension to Chimera grid techniques which allow efficient computations on flexible meshes, and discuss data-based...

The under integration of the volume terms in the discontinuous Galerkin spectral element approximation introduces errors at non-conforming element faces that do not cancel and lead to free-stream preservation errors. We derive volume and face conditions on the geometry under which a constant state is preserved. From those, we catalog eight constrai...

This work is focused on the entropy analysis of a semi-discrete nodal discontinuous Galerkin spectral element method (DGSEM) on moving meshes for hyperbolic conservation laws. The DGSEM is constructed with a local tensor-product Lagrange-polynomial basis computed from Legendre-Gauss-Lobatto (LGL) points. Furthermore, the collocation of interpolatio...

This work is focused on the entropy analysis of a semi-discrete nodal discontinuous Galerkin spectral element method (DGSEM) on moving meshes for hyperbolic conservation laws. The DGSEM is constructed with a local tensor-product Lagrange-polynomial basis computed from Legendre-Gauss-Lobatto (LGL) points. Furthermore, the collocation of interpolatio...

This paper summarizes our progress in the application of a high-order discontinuous Galerkin (DG) method for scale resolving fluid dynamics simulations on the Cray XC40 Hazel Hen cluster at HLRS. We present the large eddy simulation (LES) of flow around a wall mounted cylinder, a LES of flow around an airfoil at realistic Reynolds number using a re...

In this report we give an overview of our high-order simulations of turbulent flows carried out on the HLRS systems. The simulation framework is built around a highly scalable solver based on the discontinuous Galerkin spectral element method (DGSEM). It has been designed to support large scale simulations on massively parallel architectures and at...

The book describes the main findings of the EU-funded project IDIHOM (Industrialization of High-Order Methods – A Top-Down Approach). The goal of this project was the improvement, utilization and demonstration of innovative higher-order simulation capabilities for large-scale aerodynamic application challenges in the aircraft industry. The IDIHOM c...

In the development of the next generation of numerical methods for CFD, Discontinuous Galerkin methods are promising a substantial increase in efficiency and accuracy. While the particular high order methods can be very distinct, they have in common that they must rely on a high-order approximation of curved geometries to maintain their high-order...

In this article, we describe the capabilities of high order discontinuous Galerkin methods at the Institute for Aerodynamics and Gasdynamics for the Large-Eddy Simulation of wall-bounded flows at moderate Reynolds numbers. In these scenarios, the prediction of laminar regions, flow transition and developed turbulence poses a great challenge to the...

High order methods are regarded as a primary means to significantly improve the efficiency of numerical techniques. While the particular high order methods can be very distinct, most have in common that their solution is represented by piecewise polynomials. However, since high order methods evolved only recently, most of the present visualization...

In this work we apply the high-order discontinuous Galerkin spectral element method (DGSEM) with explicit Runge-Kutta time integration to a classical square duct channel flow problem, which is a widely used benchmark case for turbulent flows. We show that due to its good scale resolving capabilities and low dispersion and dissipation errors DGSEM i...

Due to the broad range of spatial and temporal structures of turbulent flows, the resolution requirements for a fully resolved representation of all scales are prohibitively expensive and make Direct Numerical Simulations (DNS) impossible in all but a very limited number of cases.

In this paper, we investigate the accuracy and efficiency of discontinuous Galerkin spectral method simulations of under-resolved transitional and turbulent flows at moderate Reynolds numbers, where the accurate prediction of closely coupled laminar regions, transition and developed turbulence presents a great challenge to large eddy simulation mod...

In this work we consider and compare different gasdynamic models for the simulation of turbulent flows. We choose three different continuum models based on the full Boltzmann equations , namely the Navier-Stokes-Fourier equations, the Grad 13 equations and the regularized Grad 13 equations. For the numerical experiment a massively parallel disconti...

In this report we present selected simulations performed on the HLRS clusters. Our simulation framework is based on the Discontinuous Galerkin method and consists of four different codes, each of which is developed with a distinct focus. All of those codes are written with a special emphasis on (MPI) based high performance computing. In this report...