setting sail

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

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+sims/*
+!*/.keep
+.direnv

README.md

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+# OpenFOAM nix shell environment
+
+## Usage
+
+With `direnv` installed and active (`eval $"(direnv hook bash)"`) the 
+environment loads itself when you enter this directory or any below it.
+Simulations can be placed inside the `sims` directory. The `sims` 
+directory is ignored by git. If you change branches your simulations 
+should stay untouched. However it may lead to confusion if you have
+simulation results from one OpenFOAM version and then change to another.
+Clone this repository again for each OpenFOAM version you want to use to
+not confuse yourself ;-)
+
+## Requirements
+
+### nix with flakes
+On `nixos` flakes can be enabled by adding the following to your system
+configuration:
+
+``` nix
+nix.settings.experimental-features = [ "nix-command" "flakes" ];
+```
+
+On other systems add the following to your `/etc/nix/nix.conf`:
+
+``` conf
+experimental-features = nix-command flakes
+```
+
+### direnv
+
+After installing `direnv` it has to be loaded. Maybe add the hook to your
+shellrc:
+
+``` sh
+echo 'eval "$(direnv hook bash)"' >> ~/.bashrc
+```
+
+See https://direnv.net/docs/hook.html for more information.
+You'll need to `allow` the current directory:
+
+``` sh
+direnv allow
+```
+
+## Update nixpkgs
+
+From within this directory run
+
+``` sh
+nix flake update
+```
+
+to pin to the latest `nixpkgs` version.
+
+## Update OpenFOAM version
+
+The OpenFOAM derivation is defined in `pkgs/openfoam/default.nix`. Edit the
+variables in the `let` block at the top of the file and replace the 
+`"sha256-..."` string with an empty string. The first build will then fail 
+and give you the correct sha hash. Replace the empty string with it.
+
+## Add different OpenFOAM release
+
+There are branches for each OpenFOAM release. The main branch has always the 
+latest version. If you want to add a new one:
+
+- create a new branch to hold the current version (e.g. openfoam-12)
+- update the repository path in `pkgs/openfoam/default.nix` by editing the
+  parameters in the `let` block.
+- adjust the `patches`, `postPatch`, `configurePhase`, `buildPhase` and 
+  `installPhase` if required
+
+Reevaluating `envrc` will build the new OpenFOAM (this may take a while (expect
+ up to 1h).

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1744868846,
+        "narHash": "sha256-5RJTdUHDmj12Qsv7XOhuospjAjATNiTMElplWnJE9Hs=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "ebe4301cbd8f81c4f8d3244b3632338bbeb6d49c",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "OpenFOAM 12 Simulation Environment for pirates";
+
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem
+      (system:
+        let pkgs = nixpkgs.legacyPackages.${system}; in
+        {
+          devShells.default = import ./shell.nix { inherit pkgs; };
+        }
+      );
+}

pkgs/openfoam/0001-etc-bashrc-add-placeholder-for-FOAM_INST_DIR.patch

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+From 8043842ab7feceae999addf2725d44ab0f65071a Mon Sep 17 00:00:00 2001
+From: Sebastian Woetzel <wose@zuendmasse.de>
+Date: Sun, 20 Apr 2025 18:00:41 +0200
+Subject: [PATCH] etc/bashrc: add placeholder for FOAM_INST_DIR
+
+---
+ etc/bashrc | 11 ++---------
+ 1 file changed, 2 insertions(+), 9 deletions(-)
+
+diff --git a/etc/bashrc b/etc/bashrc
+index 1ead5cc1c7..59d0bdb2ad 100644
+--- a/etc/bashrc
++++ b/etc/bashrc
+@@ -42,15 +42,8 @@ export WM_PROJECT_VERSION=12
+ # the directory two levels below this file, or $HOME/$WM_PROJECT if that
+ # directory cannot be determined.
+ #
+-[ "$BASH" ] && bashrcFile=${BASH_SOURCE}
+-[ "$ZSH_NAME" ] && bashrcFile=$0
+-if [ -n "$bashrcFile" ]
+-then
+-    export FOAM_INST_DIR=$(cd $(dirname $bashrcFile)/../.. && pwd -P)
+-else
+-    export FOAM_INST_DIR=$HOME/$WM_PROJECT
+-fi
+-unset bashrcFile
++# FOAM_INST_DIR is set in postPatch phase
++# __inst_dir_placeholder__
+ #
+ # Please set to the appropriate path if the above default is not correct. E.g.,
+ #
+-- 
+2.49.0
+

pkgs/openfoam/default.nix

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+{
+  stdenv,
+  lib,
+  pkgs,
+  ...
+}: let
+  version = "12.20250206";
+  major = "12";
+  revision = "20250206";
+  realname = "OpenFOAM";
+in let
+  pkg = stdenv.mkDerivation {
+    pname = "openfoam";
+    inherit version major;
+
+    src = pkgs.fetchFromGitHub {
+      owner = realname;
+      repo = "${realname}-${major}";
+      rev = "${revision}";
+      sha256 = "sha256-MZ29G5+49ZjE2hHC4uRF6PTR7cI5hrdjOn66lMnIgIw=";
+    };
+
+    nativeBuildInputs = with pkgs; [bash m4 flex bison];
+
+    buildInputs = with pkgs; [fftw mpi scotch boost cgal zlib];
+
+    patches = [
+      ./0001-etc-bashrc-add-placeholder-for-FOAM_INST_DIR.patch
+    ];
+
+    postPatch = ''
+      substituteInPlace etc/bashrc \
+        --replace 'export SCOTCH_TYPE=ThirdParty' 'export SCOTCH_TYPE=system' \
+        --replace 'export ZOLTAN_TYPE=ThirdParty' 'export ZOLTAN_TYPE=none'
+
+      patchShebangs Allwmake
+      patchShebangs etc
+      patchShebangs wmake
+      patchShebangs applications
+      patchShebangs bin
+    '';
+
+    configurePhase = ''
+      export FOAM_INST_DIR=$NIX_BUILD_TOP/source
+      export WM_PROJECT_DIR=$FOAM_INST_DIR/${realname}-${major}
+      mkdir $WM_PROJECT_DIR
+
+      mv $(find $FOAM_INST_DIR/ -maxdepth 1 -not -path $WM_PROJECT_DIR -not -path $FOAM_INST_DIR/) \
+          $WM_PROJECT_DIR/
+
+      set +e
+      . $WM_PROJECT_DIR/etc/bashrc
+      set -e
+    '';
+
+    buildPhase = ''
+      sh $WM_PROJECT_DIR/Allwmake -j$CORES
+      wclean all
+      wmakeLnIncludeAll
+    '';
+
+    installPhase = ''
+      mkdir -p $out/${realname}-${major}
+
+      substituteInPlace $WM_PROJECT_DIR/etc/bashrc \
+          --replace '# __inst_dir_placeholder__' "export FOAM_INST_DIR=$out"
+
+      cp -Ra $WM_PROJECT_DIR/* $out/${realname}-${major}
+    '';
+
+    passthru = {
+      shellHook = ''
+        . ${pkg}/${realname}-${major}/etc/bashrc
+      '';
+    };
+
+    meta = with pkgs.lib; {
+      homepage = "https://www.openfoam.org/";
+      description = "OpenFOAM is a free, open source CFD software released and developed by OpenFOAM Foundation";
+      license = licenses.gpl3;
+      platforms = platforms.linux;
+      maintainers = [ "wose" ];
+      broken = pkgs.stdenv.isDarwin;
+    };
+  };
+in
+  pkg

shell.nix

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+{ pkgs ? import <nixpkgs> { } }:
+with pkgs;
+mkShell rec {
+  openfoam = callPackage ./pkgs/openfoam/default.nix { };
+  buildInputs = [
+    gnumake
+    mpi
+    openfoam
+  ];
+
+  shellHook = ''
+    echo "⠀⢰⣿⣷⣦⣄⡀⠀⣀⣀⣀⣀⣀⡀⠀⢀⣠⣴⣶⣿⡆"
+    echo "⠀⢸⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡃"
+    echo "⠀⠈⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿"
+    echo "⠀⠀⢸⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡇"⠀
+    echo "⠀⢀⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡄"⠀
+    echo "⠀⢸⣿⣿⠟⠁⠀⠈⢹⣿⣿⣿⣿⠏⠁⠀⠙⢻⣿⣿⡇"
+    echo "⠀⠈⢿⣿⣷⣄⣀⣠⣼⣿⣿⣿⣿⣦⣀⣀⣠⣾⣿⡿"
+    echo "⢠⣤⡀⠉⠻⠿⣿⣿⣿⣿⣷⣿⣿⣿⣿⣿⣿⠿⠟⢁⣤⣄"
+    echo "⣼⣿⣿⣦⣄⡀⠘⠿⠻⠿⠟⠿⡿⠻⠿⠀⢀⣀⣤⣾⣿⣧⡀"
+    echo "⠉⠉⠉⠉⠛⠿⣿⣷⣶⣤⣀⣀⣤⣶⣾⣿⠿⠟⠋⠉⠉⠛"
+    echo "⢀⡀⠀⠀⢀⣀⣤⣴⣿⣿⠿⠿⣿⣿⣦⣤⣀⡀⠀⠀⢀⡀"
+    echo "⢿⣿⣷⣾⠿⠟⠛⠋⠁⠀⠀⠀⠀⠈⠙⠛⠻⢿⣷⣶⣿⣿⠆"
+    echo "⠘⢿⡿⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢿⣿⡇⠀"
+    echo ""
+    echo "Setting sail to the open foaming sea!"
+    echo "Arrrrr!"
+    echo ""
+    . ${openfoam}/OpenFOAM-12/etc/bashrc
+  '';
+}