1. OpenFOAM on Ubuntu 24.04: System Check and Dual-Version Plan

The setup in this article was built and tested on Ubuntu 24.04 LTS (Noble). OpenFOAM Foundation 14 provides an official Ubuntu package for 24.04 LTS, and the OpenCFD v2606 release also provides precompiled packages for Ubuntu 24.04.

Check the operating-system release before starting:

lsb_release -a

The key design decision is simple: neither OpenFOAM distribution will be sourced automatically in a normal terminal. We will install both first, then create controlled child shells for each one.

2. Install OpenFOAM Foundation 14

For Foundation 14, use the official OpenFOAM Foundation Ubuntu installation guide. The official method uses the Foundation package repository and installs the package named openfoam14. Readers who want to inspect the source tree can also use the official OpenFOAM Foundation 14 repository on GitHub.

Add the Official Foundation Repository

Make sure the basic repository tools are available:

sudo apt update

sudo apt install -y wget ca-certificates software-properties-common

Install the official repository signing key:

sudo sh -c "wget -O - https://dl.openfoam.org/gpg.key > /etc/apt/trusted.gpg.d/openfoam.asc"

If an older dl.openfoam.org source-list entry is already on the machine, remove the old entry before adding the current repository:

sudo rm -f /etc/apt/sources.list.d/*dl_openfoam_org*list

Add the official Foundation repositories:

sudo add-apt-repository "http://dl.openfoam.org/ubuntu main dev"

Refresh APT and install OpenFOAM 14:

sudo apt update

sudo apt -y install openfoam14

The official package places OpenFOAM 14 under /opt/openfoam14. Do not manually relocate this directory; it is managed by the Ubuntu package.

3. Verify OpenFOAM 14 and Copy the Tutorials

The official Foundation single-version workflow normally recommends sourcing /opt/openfoam14/etc/bashrc from ~/.bashrc. For this dual-version workstation, we first use it only for a temporary installation check:

source /opt/openfoam14/etc/bashrc

Verify the active version, project directory, tutorial directory, and blockMesh executable:

foamVersion

echo $WM_PROJECT_DIR

echo $FOAM_TUTORIALS

which blockMesh

A correct installation should resolve the project directory to /opt/openfoam14 and the official tutorial tree to /opt/openfoam14/tutorials. The Foundation guide also uses foamRun -help as an installation check:

foamRun -help

Create a Writable Foundation Workspace

The official Foundation getting-started workflow creates a user project directory under $HOME/OpenFOAM and a run directory. We follow the same principle, but copy the complete tutorial collection so the system installation remains untouched.

mkdir -p "$WM_PROJECT_USER_DIR/run"

cp -a --no-preserve=ownership "$FOAM_TUTORIALS" "$WM_PROJECT_USER_DIR/run/"

The resulting working tree follows this pattern: ~/OpenFOAM/<username>-14/run/tutorials. From this point onward, modify and run tutorial cases from the user copy, not directly from /opt/openfoam14/tutorials.

4. Install OpenFOAM OpenCFD v2606

OpenFOAM v2606 belongs to the OpenCFD release line. The official current-release page identifies v2606 as the June 2026 release, and the official Linux installation page points Debian and Ubuntu users to precompiled system packages. Its official source repository is maintained on OpenFOAM’s GitLab repository for v2606.

Start this part from a new terminal in which Foundation 14 has not been sourced. A clean terminal should return no OpenFOAM version from:

echo $WM_PROJECT_VERSION

which blockMesh

Add the Official OpenCFD Debian/Ubuntu Repository

Install the small set of tools needed by the repository installer:

sudo apt update

sudo apt install -y curl ca-certificates

Then run the official OpenCFD repository helper:

curl -s https://dl.openfoam.com/add-debian-repo.sh | sudo bash

The helper adds the repository signing key, configures the repository for the detected Linux distribution, and refreshes package metadata. Running sudo apt update again is harmless and makes the next step explicit:

sudo apt update

Confirm that the v2606 meta-package is visible:

apt-cache policy openfoam2606-default

Install the normal v2606 package set:

sudo apt install -y openfoam2606-default

The OpenCFD package description defines openfoamVER-default as the meta-package containing the components normally required for that release.

5. Verify v2606 and Build Separate Workspaces

Activate v2606 temporarily for the installation check:

source /usr/lib/openfoam/openfoam2606/etc/bashrc

Verify the release and the two main installation paths:

foamVersion

echo $WM_PROJECT_DIR

echo $FOAM_TUTORIALS

The expected project path is /usr/lib/openfoam/openfoam2606, and the official tutorials are located under /usr/lib/openfoam/openfoam2606/tutorials.

Because the later OceanTechReview Overset track uses the v2606 Overset applications, verify that the executables are present:

which overPimpleDyMFoam

which overInterDyMFoam

Copy the v2606 Tutorials into the User Workspace

As with Foundation 14, keep the package-managed tutorial tree unchanged and work from a copy in the user’s home directory:

mkdir -p "$WM_PROJECT_USER_DIR/run"

cp -a --no-preserve=ownership "$FOAM_TUTORIALS" "$WM_PROJECT_USER_DIR/run/"

The two independent workspaces now follow this structure:

~/OpenFOAM/<username>-14/run/tutorials
~/OpenFOAM/<username>-v2606/run/tutorials

6. Why the Two OpenFOAM Versions Use Different Paths

A common question at this point is why Foundation 14 is installed in /opt/openfoam14 while v2606 appears under /usr/lib/openfoam/openfoam2606. The answer is packaging: these directories are selected by the maintainers of the two distributions, not by this tutorial.

The Foundation Ubuntu instructions state that OpenFOAM 14 is installed in /opt. OpenCFD’s Debian/Ubuntu package documentation places the main versioned installations under /usr/lib/openfoam and explicitly describes that layout as supporting multiple installed versions.

This separation is also useful conceptually: the two directory trees make it immediately visible that Foundation 14 and OpenCFD v2606 are independent software distributions even though they share the OpenFOAM name and a large body of CFD concepts.

7. Why the Environments Must Stay Isolated

Installing both packages side by side is safe. The subtle problem begins if one environment is sourced on top of the other in the same shell. OpenFOAM startup scripts modify variables such as PATH, LD_LIBRARY_PATH, WM_PROJECT_DIR, and FOAM_TUTORIALS.

During development of this setup, a v2606 Allrun script attempted to locate geometry under an OpenFOAM 14 tutorial path. The active solver belonged to v2606, but part of the shell environment still pointed at Foundation 14. That is exactly the kind of silent cross-version contamination this design is intended to prevent.

The target behaviour is therefore deliberate: a new normal terminal has no active OpenFOAM version. of14 opens a Foundation shell, of2606 opens a v2606 shell, and exit returns to the clean parent terminal.

8. Create the of14 and of2606 Commands

The dual-version setup uses simple Bash aliases instead of separate OpenFOAM shell configuration files. The commands are stored in ~/.bash_aliases, which keeps the normal Ubuntu terminal clean while allowing each OpenFOAM version to be activated only when required.

First make sure that no OpenFOAM version is automatically loaded from ~/.bashrc. Any permanent line such as:

. /opt/openfoam14/etc/bashrc

should be removed or commented out.

Add the OpenFOAM Commands to ~/.bash_aliases

Open the aliases file:

nano ~/.bash_aliases

Add the following functions:

# OpenFOAM 14
of14()
{
    source /opt/openfoam14/etc/bashrc
}

# OpenFOAM v2606
of2606()
{
    source /usr/lib/openfoam/openfoam2606/etc/bashrc
}

Reload the normal Bash configuration:

source ~/.bashrc

The normal terminal should now remain clean until one of these commands is called:

of14

of2606

9. Final Verification, Daily Workflow, and Troubleshooting

Open a new normal terminal. Before launching either version, verify that echo $WM_PROJECT_VERSION is empty and which blockMesh does not resolve to an OpenFOAM executable.

Run Tutorials from the User Copy

For the simplest daily workflow, open the copied case directory in the Ubuntu file manager, choose Open in Terminal, and then run of14 or of2606. The launcher activates the selected OpenFOAM environment while leaving the terminal inside that case. The parent run directory does not necessarily contain an Allrun file.

If the case provides an Allrun script, it can normally be run directly with ./Allrun; many tutorials also provide ./Allclean for resetting generated files. The script itself sources OpenFOAM’s RunFunctions when required, so users do not need to source that helper manually before running the script. Individual applications can still be executed one by one when the workflow needs to be inspected or documented in more detail.

Installation and Environment Troubleshooting

NO_PUBKEY or repository-signature errors: reinstall the official Foundation signing key and run sudo apt update again. Do not disable package-signature verification.

Unmet dependencies for openfoam14: the official Foundation installation guide identifies a disabled Ubuntu universe repository as a common cause. Enable it with sudo apt-add-repository universe and then run sudo apt update.

Hash Sum mismatch: clear the APT cache with sudo apt clean, refresh package metadata, and retry. Do not force installation of a package whose checksum does not match.

foamVersion: command not found: no OpenFOAM environment is active. Use of14 or of2606.

ParaView reports “could not connect to display :0” or an xcb platform-plugin error: on an Ubuntu Wayland desktop, first exit the OpenFOAM shell, reload ~/.bashrc, and launch it again so the updated desktop-session variables are inherited. Inside the OpenFOAM shell, echo $WAYLAND_DISPLAY should be non-empty and echo $QT_QPA_PLATFORM should report wayland. The launcher also preserves XAUTHORITY for X11/Xwayland compatibility.

cannot open /bin/tools/RunFunctions: this normally means $WM_PROJECT_DIR is empty. Enter the correct OpenFOAM shell first and then rerun the tutorial.

v2606 points to an OpenFOAM 14 tutorial directory: leave the current shell with exit and start of2606 from a clean normal terminal. Do not source one version over the other.