#!/usr/bin/env bash
# Generic external-flow OpenFOAM case for an arbitrary STL body (normalized L=1,
# centred at origin). Steady RANS k-omega-SST, matching EZFlow non-dim (U=1,
# rho=1, nu=1/Re). snappyHexMesh with feature capture + boundary layers.
# Usage: of_external.sh <stl_path> <Re> <Aref> <case_name>
source /usr/lib/openfoam/openfoam2512/etc/bashrc
STL="$1"; RE="$2"; AREF="$3"; NAME="$4"
NU=$(awk "BEGIN{printf \"%.8g\", 1.0/$RE}")
K0=0.00375; OMEGA0=1.6
CASE=/root/of_ext/${NAME}_re${RE}
MB="$FOAM_TUTORIALS/incompressible/simpleFoam/motorBike"

echo "=== build $CASE  (Re=$RE nu=$NU Aref=$AREF stl=$STL) ==="
rm -rf "$CASE"; mkdir -p "$CASE/0" "$CASE/constant/triSurface" "$CASE/system"
cp "$MB/system/fvSchemes"  "$CASE/system/fvSchemes"
cp "$MB/system/fvSolution" "$CASE/system/fvSolution"
cp "$STL" "$CASE/constant/triSurface/body.stl"

hdr(){ echo "FoamFile{version 2.0;format ascii;class $1;object $2;}"; }
{ hdr dictionary transportProperties; echo "transportModel Newtonian;";
  echo "nu [0 2 -1 0 0 0 0] $NU;"; } > "$CASE/constant/transportProperties"
{ hdr dictionary turbulenceProperties; echo "simulationType RAS;";
  echo "RAS{ RASModel kOmegaSST; turbulence on; printCoeffs on; }"; } \
  > "$CASE/constant/turbulenceProperties"

cat > "$CASE/system/controlDict" <<EOF
$(hdr dictionary controlDict)
application simpleFoam; startFrom startTime; startTime 0; stopAt endTime;
endTime 1500; deltaT 1; writeControl timeStep; writeInterval 1500; purgeWrite 1;
writeFormat ascii; writePrecision 7; writeCompression off; runTimeModifiable true;
functions{ forceCoeffs1{ type forceCoeffs; libs ("libforces.so");
  writeControl timeStep; writeInterval 1; patches (body); rho rhoInf; rhoInf 1;
  magUInf 1; lRef 1; Aref $AREF; liftDir (0 1 0); dragDir (1 0 0);
  pitchAxis (0 0 1); CofR (0 0 0); } }
EOF

cat > "$CASE/system/blockMeshDict" <<'EOF'
FoamFile{version 2.0;format ascii;class dictionary;object blockMeshDict;}
scale 1;
vertices ( (-6 -6 -6) (18 -6 -6) (18 6 -6) (-6 6 -6)
           (-6 -6  6) (18 -6  6) (18 6  6) (-6 6  6) );
blocks ( hex (0 1 2 3 4 5 6 7) (48 24 24) simpleGrading (1 1 1) );
edges ();
boundary ( inlet { type patch; faces ((0 4 7 3)); }
           outlet { type patch; faces ((1 5 6 2)); }
           farfield { type patch; faces ((1 5 4 0)(3 7 6 2)(0 3 2 1)(4 5 6 7)); } );
mergePatchPairs ();
EOF

cat > "$CASE/system/surfaceFeatureExtractDict" <<'EOF'
FoamFile{version 2.0;format ascii;class dictionary;object surfaceFeatureExtractDict;}
body.stl { extractionMethod extractFromSurface;
  extractFromSurfaceCoeffs { includedAngle 150; } writeObj no; }
EOF

cat > "$CASE/system/snappyHexMeshDict" <<'EOF'
FoamFile{version 2.0;format ascii;class dictionary;object snappyHexMeshDict;}
castellatedMesh true; snap true; addLayers true;
geometry { body { type triSurfaceMesh; file "body.stl"; } }
castellatedMeshControls
{
    maxLocalCells 2000000; maxGlobalCells 8000000; minRefinementCells 10;
    nCellsBetweenLevels 3; resolveFeatureAngle 30; allowFreeStandingZoneFaces true;
    features ( { file "body.eMesh"; level 4; } );
    refinementSurfaces { body { level (3 4); patchInfo { type wall; } } }
    refinementRegions { body { mode distance; levels ((0.5 3) (1.5 2) (3.0 1)); } }
    locationInMesh (-5 0.013 0.027);
}
snapControls { nSmoothPatch 3; tolerance 2.0; nSolveIter 50; nRelaxIter 8;
  nFeatureSnapIter 10; implicitFeatureSnap false; explicitFeatureSnap true; }
addLayersControls
{
    relativeSizes true; expansionRatio 1.2; finalLayerThickness 0.5; minThickness 0.05;
    layers { body { nSurfaceLayers 4; } }
    nGrow 0; featureAngle 80; nRelaxIter 5; nSmoothSurfaceNormals 1;
    nSmoothNormals 3; nSmoothThickness 10; maxFaceThicknessRatio 0.5;
    maxThicknessToMedialRatio 0.3; minMedialAxisAngle 90;
    nBufferCellsNoExtrude 0; nLayerIter 50;
}
meshQualityControls
{
    maxNonOrtho 65; maxBoundarySkewness 20; maxInternalSkewness 4; maxConcave 80;
    minVol 1e-13; minTetQuality 1e-15; minArea -1; minTwist 0.02;
    minDeterminant 0.001; minFaceWeight 0.05; minVolRatio 0.01; minTriangleTwist -1;
    nSmoothScale 4; errorReduction 0.75; relaxed { maxNonOrtho 75; }
}
mergeTolerance 1e-6;
EOF

# 0/ fields (flow +x; wall patch = body)
cat > "$CASE/0/U" <<EOF
$(hdr volVectorField U)
dimensions [0 1 -1 0 0 0 0]; internalField uniform (1 0 0);
boundaryField{ inlet{type fixedValue;value uniform (1 0 0);}
 outlet{type inletOutlet;inletValue uniform (0 0 0);value uniform (1 0 0);}
 farfield{type slip;} body{type noSlip;} }
EOF
cat > "$CASE/0/p" <<EOF
$(hdr volScalarField p)
dimensions [0 2 -2 0 0 0 0]; internalField uniform 0;
boundaryField{ inlet{type zeroGradient;} outlet{type fixedValue;value uniform 0;}
 farfield{type slip;} body{type zeroGradient;} }
EOF
cat > "$CASE/0/nut" <<EOF
$(hdr volScalarField nut)
dimensions [0 2 -1 0 0 0 0]; internalField uniform 0;
boundaryField{ inlet{type calculated;value uniform 0;} outlet{type calculated;value uniform 0;}
 farfield{type calculated;value uniform 0;} body{type nutkWallFunction;value uniform 0;} }
EOF
cat > "$CASE/0/k" <<EOF
$(hdr volScalarField k)
dimensions [0 2 -2 0 0 0 0]; internalField uniform $K0;
boundaryField{ inlet{type fixedValue;value uniform $K0;}
 outlet{type inletOutlet;inletValue uniform $K0;value uniform $K0;}
 farfield{type zeroGradient;} body{type kqRWallFunction;value uniform $K0;} }
EOF
cat > "$CASE/0/omega" <<EOF
$(hdr volScalarField omega)
dimensions [0 0 -1 0 0 0 0]; internalField uniform $OMEGA0;
boundaryField{ inlet{type fixedValue;value uniform $OMEGA0;}
 outlet{type inletOutlet;inletValue uniform $OMEGA0;value uniform $OMEGA0;}
 farfield{type zeroGradient;} body{type omegaWallFunction;value uniform $OMEGA0;} }
EOF

cd "$CASE"
echo "=== blockMesh ==="; blockMesh > log.blockMesh 2>&1; echo "rc=$?"
echo "=== surfaceFeatureExtract ==="; surfaceFeatureExtract > log.sfe 2>&1; echo "rc=$?"
echo "=== snappyHexMesh ==="; t=$(date +%s)
snappyHexMesh -overwrite > log.snappy 2>&1; echo "snappy rc=$? in $(( $(date +%s)-t ))s"
grep -iE "Added .*cells|Layer mesh|Final" log.snappy | tail -3
echo "=== checkMesh ==="; checkMesh > log.checkMesh 2>&1
grep -iE "cells:|Mesh OK|\*\*\*" log.checkMesh | tail -4
echo "=== simpleFoam ==="; t=$(date +%s)
simpleFoam > log.simpleFoam 2>&1; echo "simpleFoam rc=$? in $(( $(date +%s)-t ))s"
grep -E "SIMPLE solution converged|Time =" log.simpleFoam | tail -2
F=$(find postProcessing -name 'coefficient*.dat' 2>/dev/null | head -1)
echo "OF_EXT_DONE name=$NAME Re=$RE Cd_Cl:"; tail -1 "$F"
EOF_GUARD=1