In this paper we describe the OpenGeoSys (OGS) project, which is a scientific open-source initiative for numerical simulation of thermo-hydro-mechanical-chemical processes in porous media. The basic concept is to provide a flexible numerical framework (using primarily the Finite Element Method (FEM)) for solving multifield problems in porous and fractured media for applications in geoscience and hydrology. To this purpose OGS is based on an object-oriented FEM concept including a broad spectrum of interfaces for pre- and postprocessing. The OGS idea has been in development since the mid-eighties. We provide a short historical note about the continuous process of concept and software development having evolved through Fortran, C, and C++ implementations. The idea behind OGS is to provide an open platform to the community, outfitted with professional software-engineering tools such as platform-independent compiling and automated benchmarking. A comprehensive benchmarking book has been prepared for publication. Benchmarking has been proven to be a valuable tool for cooperation between different developer teams, for example, for code comparison and validation purposes (DEVOVALEX and CO2 BENCH projects). On one hand, object-orientation (OO) provides a suitable framework for distributed code development; however, the parallelization of OO codes still lacks efficiency. High-performance-computing efficiency of OO codes is subject to future research.

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OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media

/pdf/opengeosys-an-open-source-initiative-for-numerical-4it7wxohfd.pdf

OpenGeoSys: An open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media

Benchmarks for single-phase flow in fractured porous media

[1] Domains composed of a porous part and an adjacent free-flow region are of special interest in many fields of application. So far, the coupling of free flow with porous-media flow has been considered only for single-phase systems. Here we extend this classical concept to two-component nonisothermal flow with two phases inside the porous medium and one phase in the free-flow region. The mathematical modeling of flow and transport phenomena in porous media is often based on Darcy's law, whereas in free-flow regions the (Navier-) -Stokes equations are used. In this paper, we give a detailed description of the employed subdomain models. The main contribution is the developed coupling concept, which is able to deal with compositional (miscible) flow and a two-phase system in the porous medium. It is based on the continuity of fluxes and the assumption of thermodynamic equilibrium, and uses the Beavers-Joseph-Saffman condition. The phenomenological explanations leading to a simple, solvable model, which accounts for the physics at the interface, are laid out in detail. Our model can account for evaporation and condensation processes at the interface and is used to model evaporation from soil influenced by a wind field in a first numerical example.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2011WR010685

A coupling concept for two-phase compositional porous-medium and single-phase compositional free flow

Numerical modelling is increasingly supporting the analysis and optimization of manufacturing processes in the production industry. Even if being mostly applied to multistep processes, single process steps may be so complex by nature that the needed models to describe them must include multiphysics. On the other hand, processes which inherently may seem multiphysical by nature might sometimes be modelled by considerably simpler models if the problem at hand can be somehow adequately simplified. In the present article, examples of this will be presented. The cases are chosen with the aim of showing the diversity in the field of modelling of manufacturing processes as regards process, materials, generic disciplines as well as length scales: (1) modelling of tape casting for thin ceramic layers, (2) modelling the flow of polymers in extrusion, (3) modelling the deformation process of flexible stamps for nanoimprint lithography, (4) modelling manufacturing of composite parts and (5) modelling the selective la...

/pdf/multiphysics-modelling-of-manufacturing-processes-a-review-15bdtre5jn.pdf

Multiphysics modelling of manufacturing processes: A review

DuMux: DUNE for multi-{phase,component,scale,physics,…} flow and transport in porous media

Numerical scheme for coupling two-phase compositional porous-media flow and one-phase compositional free flow

Achieving a substantial part of peak performance on todays and future high-performance computing systems is a major challenge for simulation codes. In this paper we address this question in the context of the numerical solution of partial differential equations with finite element methods, in particular the discontinuous Galerkin method applied to a convection-diffusion-reaction model problem. Assuming tensor product structure of basis functions and quadrature on cuboid meshes in a matrix-free approach a substantial reduction in computational complexity can be achieved for operator application compared to a matrix-based implementation while at the same time enabling SIMD vectorization and the use of fused-multiply-add. Close to 60\% of peak performance are obtained for a full operator evaluation on a Xeon Haswell CPU with 16 cores and speedups of several hundred (with respect to matrix-based computation) are achieved for polynomial degree seven. Excellent weak scalability on a single node as well as the roofline model demonstrate that the algorithm is fully compute-bound with a high flop per byte ratio. Excellent scalability is also demonstrated on up to 6144 cores using message passing.

High-performance Implementation of Matrix-free High-order Discontinuous Galerkin Methods

A stable and high-order accurate discontinuous Galerkin based splitting method for the incompressible Navier–Stokes equations

We present a Dune-Grid extension that enhances existing Dune grids with the ability to designate arbitrary subsets of their leaf entity complex as subdomains and present them as new grid objects. We describe the functionality of this module, which is called Dune-Multidomaingrid and available as free software, and outline its implementation. In particular, we highlight the performance characteristics of our module and present a way of tailoring them to a specific problem by means of a modular backend engine. Finally, we give some pointers to current applications of the module.

Steffen Müthing

Papers

DuMux: DUNE for multi-{phase,component,scale,physics,…} flow and transport in porous media

Numerical scheme for coupling two-phase compositional porous-media flow and one-phase compositional free flow

High-performance Implementation of Matrix-free High-order Discontinuous Galerkin Methods

A stable and high-order accurate discontinuous Galerkin based splitting method for the incompressible Navier–Stokes equations

Dune-Multidomaingrid: A Metagrid Approach to Subdomain Modeling