enGits GmbH is a highly specialized software developer and engineering service provider based in the town of Todtnau in Germany’s Black Forest, with more than 20 years’ experience in developing and applying simulation technology, especially in the field of CFD. enGits describes itself as a “competent partner for engineering simulation solutions. Our main strength is the field of fluid dynamics, but we are also often confronted with problems from different fields. Our applications range from ventilation in tunnels and the oil-and-gas industry all the way to space applications.”
enGits offers what it terms “software-independent consultancy, because we do not believe in one perfect software which fits all problems.” The company explains its philosophy and business approach: “Several good open-source tools exist which enable you to work very cost-effectively. Open-source also enables to tackle certain very specific problems by customizing the software. On the other hand, there are also good proprietary packages which, in many cases, might be the better choice. We use simulation software on a case-by-case basis and we can help you to choose the best software for your task.”
A significant part of enGit’s work “deals with very specific CFD tasks. Usually, these are task which cannot be solved easily with existing off-the-shelf software solutions. The picture below tries to give an impression of such a complex simulation. In this specific case, acoustic loads on the payload fairing of a launch vehicle had to be computed.”
enGrid: Open-source mesh generation software
At the same time, enGit offers two off-the-shelf software products. One, called enGrid, is open-source mesh generation code for CFD applications. enGrid uses an “in-house development for surface meshing and prismatic boundary layers,” the company says, with a module for hex far-fields planned for the next release. Tetrahedral parts of the mesh are created by calling the Netgen library. Internally, enGrid uses the VTK data structures as well as the *.vtu file format.
Currently enGrid has interfaces to Blender, Gmsh, STL and several other file formats. Gmsh can be used to import STEP and IGES files, and can also be used for simple geometry modeling. Since its 1.2 release, enGrid has provided native export to OpenFOAM, and since release 1.4 to SU2. This includes export capabilities for complete OpenFOAM cases including boundary conditions, as well as support for polyhedral cells. enGrid is released under the GPL, and is a useful addition to the open-source CFD community.
DrNUM: CFD code based on dual-resolution numerics
enGit’s other software product is DrNUM, a CFD code first introduced to the public in 2013 based on a technology called dual-resolution numerics. In contrast to the traditional CFD modeling techniques of either structured or unstructured grid, dual-resolution meshes consist of a set of super-elements with a very simple internal structure. These super-elements are called patches in the DrNUM internal terminology. Patches can be placed in freely overlapping arrangements, and constitute the actual computational grid. The company explains that dual-resolution grids “can be regarded as unstructured grids of super-elements (coarse resolution layer); each super-element, or patch, consists of a highly resolved grid portion which represents the real numerical mesh.”
At present, DrNUM supports only Cartesian super-elements. The company’s goal for DrNUM is to “achieve an optimal combination of high numerical and algorithmic efficiency within the super-elements, while keeping geometric flexibility on a higher level. This method is thus well suited to run on modern, massively parallel computing devices (e.g., GPUs). It allows processing of flow simulations on the order of dozens of millions of cells on classical single-node desktop computers.”
DrNUM is being developed jointly by enGits GmbH and numrax GmbH, a scientific and engineering organization based in Duisburg, Germany with roots in the local university that specializes in numerical methods for engineering, fluid dynamics, hydrodynamics, aeronautics, energy systems and high-performance computing. A first commercial version of DrNUM will be released in the near future, enGits says.