OpenFOAM® Tutorials

The descritization of the continous fluid is the essential task in the field of computational fluid dynamics and numerical analysis. Due to the stiff learning curve of OpenFOAM, especially at the beginning, even simple geometry meshing procedures are hard to achieve. Therefore, the following training case provides information for the first steps with snappyHexMesh.

Particular regions in a mesh could require unique properties such as the modeling of porosities or source terms. Therefore, cell zones have to be used in OpenFOAM®. SnappyHexMesh can be one way to define such zones during the meshing stage directly. Based on the snappyHexMeshDict set-up, different quality levels can be achieved. Especially the influence of the »featureEdge« feature is demonstrated in the training case.

Holzmann CFD offers a wide range of different tutorials. Uniquely focused on dynamic meshes and unique features. This training case provides all information that is required to generate a 2D arbitrary mesh interface (AMI) in OpenFOAM. As always, the example uses the popular and clean bash scripts.

Polluted air is a problem of many countries, especially in big cities or at landscapes in which the air exchange is small related to the geographical location. Thus, governments make laws such as TA-Luft, BImSchV in Germany, or stringent global regulation (world bank). Reducing the pollution of, e.g., engines, numerical methods can be used to perform optimization to the existing systems. Thus, the process can be designed more efficiently and effectively and, therefore, it is economically better.

This training case shows, in particular, the generation of the numerical mesh and set-up of the Pitot tube case that was generated for the community Christmas competition 2019. Further information about the competition is given in the » Community Competitions « section. A brief description of the case is presented in the » Publication « section.

This training case shows, in particular, the generation of the numerical mesh and set-up of the relevant OpenFOAM® functions to investigate into the community Christmas competition 2017. Further information about the competition is given in the » Community Competitions « section. A brief description of the case is presented in the » Publication « section.

In the computational fluid dynamic analysis, engineers are using a fixed rotation set-up for the moving mesh that includes the design of the turbine. However, if one is interested in a flow-induced rotation, the six degrees of freedom library in OpenFOAM® can be used to handle such analysis.

SnappyHexMesh allows using different strategies to refine different surfaces and regions. However, discretizing thin gaps in the domain can result in a challenging topic. Particularly if only triangulated surfaces are available, which cannot be split into more different surfaces that can be controlled individually within the snappyHexMesh application. As already mentioned, OpenFOAM allows different techniques to refine thin gaps. One of them is described in this tutorial.

The arbitrary coupled mesh interface (ACMI) condition is compelling if the usage of the boundary condition is well understood. The following training case builts an ACMI for a rotating inlet pipe, which is connected to a larger second pipe. The set-up is tricky and needs advanced techniques and applications for the correct ACMI generation.

SnappyHexMesh can refine defined feature edges during the refinement stage. However, many people in the community have a lot of problems with the feature edge refinement strategy. Therefore, Holzmann CFD provides the SFR case which meshes a pipe with three different surface feature refinement set-up's. The results, especially the wrong ones, might be familiar.

People all over the world who start in the field of numerical simulation begin investigating a simple pipe flow. However, for new OpenFOAM® users, even the trivial pipe meshing can be challenging. Therefore, Holzmann CFD provides two cases in which a pipe is bent under 45 degrees, and 90 degrees will be discretized. Additionally, the layer generation is applied, while a coverage rate of 99.5 percent is reached.

The in-house mesher of OpenFOAM® named snappyHexMesh is infamous in the community due to meshing problems in more advanced and complex geometries. This might be true if you are not using snappyHexMesh correctly. This training case shows the basic meshing settings for the helix geometry. Additionally, a way of the layer generation is shown which will end up with a coverage above 95 percent.

OpenFOAM® has a wide range of mesh conversion applications, that allows one to easily convert other mesh types into an OpenFOAM® readable format. This training case shows the usage of the fluent mesh converter named fluentMeshToFoam. It is worth to mention, that the cell zones created in Fluent are kept in OpenFOAM®.

The generation of the arbitrary mesh interface (AMI) boundary condition is used for rotating mesh behavior. The AMI condition interpolates values from the static mesh part onto the dynamic mesh part or vice-versa. The generation of that particular kind of boundary condition can be achieved using different methods. Commonly, Holzmann CFD uses the mesher of OpenFOAM®, namely snappyHexMesh, to generate high valuable numerical meshes.

The investigation into different phenomena can be done easily with numerical analysis. Some of the most famous phenomena are already simulated by Holzmann CFD such as the Magnus Effect, the Taylor-Rayleigh instability or the Kelvin-Helmholtz instability. People who love soccer should be aware of the Magnus effect, as it is a very common phenomenon in this kind of sport. However, it is also necessary for golf, tennis, table-tennis and so on.

In engineering applications, it is common to have active parts which connect and disconnect. Using the arbitrary coupled mesh interface in OpenFOAM® allows one to use dynamic elements that connect and disconnect during the time. The usage of such boundary conditions and the correct set-up is the principal focus of this training case.

Dynamic meshes are state of the art for engineering processes. In many cases, the numerical analysis has to be adapted to the rotation because, e.g., the multi-reference-frame (MRF) assumption does not hold anymore. To investigate such a phenomenon, OpenFOAM® offers a mapping and interpolation boundary condition, namely the arbitrary mesh interface (AMI).

The adaptive mesh refinement (AMR) method is a common strategy for significant numerical cases, including phenomena that have to be reasonably resolved (mesh density). Using the AMR functionality, OpenFOAM® allows one to refine only the regions of interest. This training case models a pseudo-2D situation.

2D and 2D rotational axis symmetric numerical meshes are used whenever it is possible. This method is related to the savings in computational effort and simplification at all. However, there are several ways to create 2D rotational axis symmetric geometries in OpenFOAM®. For more complex designs, it is worth to analyze the following training case which uses the 3D meshing tool »snappyHexMesh« to mesh the geometry in 3D first, and afterward derive the 2D rotational axis symmetric model by using other OpenFOAM® tools such as extrudeMesh and so on.

In industries such as steel producers, molds vibrate while the shell cools the moving liquid pool. Such a phenomenon is exciting and has to be considered in numerical analysis. There is a wide range of application that combines heat transfer and moving parts. Therefore, this training case demonstrates how to set-up the ACMI boundary condition correctly.

Simplifications to the numerical continuum are used in computational fluid dynamics applications almost in every scenario. In most cases, particular regions are not of primary interest. An example is given in the following training case, in which a water pump (which is just generating a pressure drop) is removed and replaced by a 1D cyclic boundary condition. The simplification leads to less numerical cells and, therefore, a reduction of computational costs.

Optimization tasks are the state of the art to optimize the design for the operating point. To prevent different modeling scenarios manually, the free software tool DAKOTA® can be used to automize the optimization task. This training case shows the coupling of both software tools, DAKOTA®, and OpenFOAM®.

In a wide range of engineering applications, the buoyancy force is the main driving force for the fluid flow. However, in the case of numerical investigations, engineers do have problems in setting up such cases or run into troubles/crashes with OpenFOAM®. This training case shows the set-up and geometry preparation of a more complex application.

Heat transfer problems, including several different regions, are state of the art simulations for CFD engineers. In each engineering application, heat transfer processes occur. Depending on the investigation, energy transport can be one of the significant quantities for which others are derived, such as thermal-induced stresses or buoyancy effects, which are based on temperature differences. The training case provides the correct set-up for such kind of problems and will guide the trainee through the different steps.

A multiphase simulation using the solver interFoam to investigate into falling droplets. The training case was invented 2017 with a former colleague Christian Gomez Rodrigues to proof an interesting statement. Based on Holzmann CFD's lack of knowledge in the field of droplets, Weber number and so on, the case is more related to be a fun investigation rather than a scientific investigation. An outcome of the fast set-up is the beautiful fluid dynamics and the corresponding velocity field.

Everybody is aware of a windscreen washer build in a car. However, most of the people think that there is a nozzle which is distributing the water onto the windscreen. This training case demonstrates the proper work of such a device. It is not a nozzle nor a mechanically driven spray generation. By using deliberate geometric designs, a fluid induced instability is generated which distributes the outcoming water stream periodically onto the object it is aimed.

Nowadays, a wide range of applications needs to be evaluated for a working point and, therefore, be designed for optimal operation. Analysis of different designs or flow parameters can be intensive work, while the data analysis is not easy. To reduce manual labor, highly advanced optimization methods - implemented in DAKOTA® - can be used in combination with OpenFOAM®. This training case shows how to couple both software tools, DAKOTA®, and OpenFOAM®.

Flow-induced rotations are state of the art problematics in computational fluid dynamics analysis such as wind turbines or Kaplan turbines. OpenFOAM® offers the possibility to use an existing library, namely the Six Degree of Freedom (6DoF) library, to model such a phenomenon. This training case will guide you through the necessary steps to simulate flow-induced rotations. The well known and structured Holzmann CFD's run script is generating the whole case automatically, and therefore, you can understand and follow each step.