Design of a Modular Monolithic Implicit Solver for Multi-Physics Applications

The design of a modular multi-physics high-order space-time finite-element framework is presented together with its extension to allow monolithic coupling of different physics. One of the main objectives of the framework is to perform efficient high- fidelity simulations of capsule/parachute systems. This problem requires simulating multiple physics including, but not limited to, the compressible Navier-Stokes equations, the dynamics of a moving body with mesh deformations and adaptation, the linear shell equations, non-re effective boundary conditions and wall modeling. The solver is based on high-order space-time - finite element methods. Continuous, discontinuous and C1-discontinuous Galerkin methods are implemented, allowing one to discretize various physical models. Tangent and adjoint sensitivity analysis are also targeted in order to conduct gradient-based optimization, error estimation, mesh adaptation, and flow control, adding another layer of complexity to the framework. The decisions made to tackle these challenges are presented. The discussion focuses first on the "single-physics" solver and later on its extension to the monolithic coupling of different physics. The implementation of different physics modules, relevant to the capsule/parachute system, are also presented. Finally, examples of coupled computations are presented, paving the way to the simulation of the full capsule/parachute system

Recent Developments for the Eddy Solver

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Towards a Discontinuous Galerkin solver for scale-resolving simulations of moderate Reynolds number flows, and application to industrial cases

Due to the continuously increasing economical and environmental constraints, the standard industrial CFD methods (mostly Reynolds Averaged Navier-Stokes equations, RANS) are no longer sufficient to answer the design requirements of the industry, in particular when off-design performance and noise need to be predicted. Therefore, scale-resolving simulations, where the full (Direct Numerical Simulation, DNS) or at least a significant portion (Large-Eddy Simulation, LES) of the turbulence spectrum is resolved, are required. However, as these simulations require a nearly flawless representation of very small turbulent structures, current industrial solvers require huge computational resources in order to provide sufficient accuracy. The discontinuous Galerkin method (DGM) could alleviate this to a large extent as it seems to bridge the gap between the flexibility of industrial codes and the accuracy of academic solvers. During this thesis, the flexibility and the parallel efficiency of a DGM solver has been improved to tackle the large requirements of DNS and LES. The method was subsequently assessed for DNS and LES based on canonical benchmarks. Due to its interesting dissipation and dispersion properties, DGM seems to offer an accuracy similar to pseudo-spectral (PS) solvers for DNS. As the dissipation targets only the smallest scales, the method seems well suited to use an implicit LES approach. This approach has been validated on the simulation of homogeneous isotropic turbulence and on the channel flow at several Reynolds numbers. Finally, the method has been successfully applied on industrial cases, including a low pressure turbine blade, airfoil profiles and a high Mach number jet flow, thereby showing the maturity of the method.(FSA - Sciences de l) -- UCL, 201

Development and Validation of a Massively Parallel High-Order Solver for DNS and LES of Industrial Flows

This work is part of the development of a new generation CFD solver, Argo, based on the discontinuous Galerkin Method (DGM), specifically targeted towards accurate, adaptive, reliable and fast DNS and LES of industrial aerodynamic flows. Several aspects were investigated in IDIHOM. A first activity was the optimisation of the parallellisation strategy, resulting in highly efficient scaling, demonstrated on some of the largest computers in Europe. A second activity concerned the assessment and validation on several academic benchmark problems of the capability of DGM to perform direct numerical simulation (DNS) and (implicit) Large Eddy Simulation (iLES). Two moderately complex flows are treated, namely the ILES of the transitional flow in the low pressure turbine cascade T106C and the isothermal jet issueing from the JEAN nozzle

The Discontinuous Galerkin Method as an Enabling Technology for DNS and LES of Industrial Aeronautical Applications

To enhance prediction capacities and therefore allow more advanced aeronautic and aero-propulsive design, new CFD tools are required. State of the art codes are based on second order accurate finite volume methods and are primarily developed for statistical turbulence modeling approaches. Given the limitations of these models, more direct approaches such as DNS or LES are required for the prediction of off-design aerodynamic performance, noise generation, transitional flows ..

DNS and ILES of transitional flows around a SD7003 using a high order Discontinuous Galerkin Method

peer reviewe

DNS of a Low Pressure Turbine Blade Computed With the Discontinuous Galerkin Method

peer reviewedThe direct numerical simulation of a turbine cascade at Reis = 85000 and Mis = 0.6 has been undertaken using a fourth-order accurate discontinuous Galerkin / symmetric interior penalty method. This method combines the high accuracy, typical of the dedicated academic DNS and LES codes, to the geometrical flexibility of industrial finite volume codes. It also allows for visual inspection of grid resolution, based on the continuity of the computed fields. Finally it attains high serial and parallel performance due to the exploitation of the high locality of the data. For these reasons it is expected that the method will enable the reliably resolved DNS and LES computations in turbomachinery industry. The accuracy with respect to dedicated academic codes is assessed on the computation of the Taylor-Green vortex. For the turbine case, the computed flow fields are compared to those obtained by large eddy simulations using a finite volume solver, and relative costs for a given resolution are estimated

Towards wall-modelled implicit LES with a discontinuous Galerkin method

peer reviewe