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Simon Leistikow edited this page May 19, 2025 · 11 revisions

OpenLB

OpenLB is an open-source C++ library for performing lattice Boltzmann method (LBM) simulations. It is designed for computational fluid dynamics (CFD) applications and supports high-performance computing (HPC). OpenLB is widely used in academia and industry for simulating complex fluid flow problems, including turbulence, multiphase flows, and heat transfer.

Within Voreen, OpenLB enables the generation of flow simulations directly integrated into the visualization pipeline.

Respective demo workspaces and data can be found in the module folder.

Building the OpenLB module with Voreen

The general procedure for building Voreen is outlined in the Build Instructions To enable OpenLB functionality, specifically for simulating fluid flows, you must include the following Voreen modules:

  • VRN_MODULE_FLOWANALYSIS
  • VRN_MODULE_FLOWSIMULATION

Steps:

  • Open the CMake GUI (either using the existing cache or starting from scratch).
  • Select the modules VRN_MODULE_FLOWANALYSIS and VRN_MODULE_FLOWSIMULATION. voreen modules
  • Press Configure, Generate and build Voreen again.
  • For Linux:
    In Build Instructions after starting the build of Voreen with typing ņinja you can also type ninja OpenLB and start a further building process.
  • For Windows:
    Due to Windows-specific limitations, you will need to use WSL (Windows Subsystem for Linux). See the section OpenLB for Windows.

Usage of OpenLB in Voreen

To leverage OpenLB in Voreen, two processors are available:

  • FlowSimulation
  • FlowSimulationCluster

Both processors support the creation of simulation ensembles. The key difference is that FlowSimulationCluster allows for execution across computing clusters, facilitating HPC environments.

Simulation Use Cases

Three use cases demonstrate how OpenLB can be used in Voreen:

UseCase A - Simulating flow based on geometries in .stl format.
UseCase B - Simulating flow based on measured flow data.
UseCase C - Analysis of simulations and measurements.

OpenLB for Windows

To use OpenLB with Voreen on Windows, you need to:

  • Enable the module FLOWSIMULATION.
  • Install a Linux distribution via WSL (e.g.: Ubuntu 24.04).

WSL installation

  • Open Windows terminal and type wsl --install
  • After the installation, you have to restart your computer. Then starting Ubuntu and setting a username and password delivers Ubuntu picture

In the Ubuntu Terminal

  • Setup the Ubuntu environment with
sudo apt-get update, sudo apt-get upgrade, sudo apt install gcc g++ make
  • Install some packages for better usage of OpenLB
sudo apt-get install openmpi-bin openmpi-doc libopenmpi-dev
  • Furthermore we need a version of vtk. In our example for Ubuntu 24.04 we take vtk9
sudo apt install libvtk9-dev

In the explorer

  • Open the module path in your voreen repositors relative-path\voreen\voreen\modules\flowsimulation\ext and copy the folder openlb to the Ubuntu system that has been created with WSL ubuntu\home\user-name. ubuntu openlb
  • Note: The folder openlb contains a config.mk file, which has to be adjusted. Here, we suggest a specific setting oriented on Ubuntu 24.04 considering vtk9.
  • Open the openlb folder in the ubuntu path and copy paste the entries from _config.mk to config.mk so that both files contain the same information.
  • Then, copy and past the following into the end of the config.mk file
# optional include paths
CXXFLAGS += -I/usr/include/vtk-9.1

# optional linker flags
LDFLAGS         := -lvtkCommonCore-9.1 -lvtkIOXML-9.1 -lvtkCommonDataModel-9.1

In the Ubuntu terminal

  • Navigate to openlb/voreen and type in make. Note that there are probably problems depending on the permission level of root and the user. To solve them, transfer the folder rights to your user by
sudo chown -R user_name:user_name ~/openlb

Build Voreen again: After all of the beforementioned steps, build Voreen again with CMake and Visual Studio as described Build Instructions. Make sure to select the module FLOWSIMULATION. Other interesting modules in this context are VESSELNETWORKANALYSIS, VTK, FLOWANALYSIS and ENSEMBLEANALYIS.

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