Meeting-notes.md

@@ -12,9 +12,7 @@ If plicRDF is not second-order accurate, we don't have any chance of advecting t
 
 * Run 
 
-```
-openfoam/tutorials/multiphase/interIsoFoam/discInReversedVortexFlow
-```
+`openfoam/tutorials/multiphase/interIsoFoam/discInReversedVortexFlow`
 
 with a droplet advected on the bottom wall (Mathis et al.) 
 
@@ -22,6 +20,34 @@ with a droplet advected on the bottom wall (Mathis et al.)
 
 Look at [reconstructionSchemes](https://www.openfoam.com/documentation/guides/latest/api/classFoam_1_1reconstructionSchemes.html) member functions `center` and `normal` : those are the PLIC plane point and normal. Use those to calculate contact angle.
 
+`//Jun: reference to reconstructionSchemes
+const reconstructionSchemes& surf = advector.surf(); 
+
+const point x0 = surf.centre()[faceOwner[faceI]];
+   25             // cell interface unit normal
+   26             vector n0 = surf.normal()[faceOwner[faceI]];
+
+`
+
+Loop over all boundaries of alpha, ask if a boundary patch is a wall, loop over all faces of the boundary patch, use the code snippet above to fetch center and normal, do some geometry to get contact angle.
+
+**FYI**: that's how we could calculate alphaf without interpolation! 
+
+`
+            // cell interface centre
+            const point x0 = surf.centre()[faceOwner[faceI]]; 
+            // cell interface unit normal
+            vector n0 = surf.normal()[faceOwner[faceI]]; 
+            n0 /= (mag(n0)+SMALL);
+            cutFace.calcSubFace(faceI, n0, x0);
+            alphaf[faceI] = mag(cutFace.subFaceArea()) / sfArea; 
+`
+
+A global object that you initialize outside the boundary field loop
+
+`cutFaceAdvect cutFace(alpha1.mesh(), alpha1);`
+
+
 * Prepare a notebook that evaluates Figure 16b for plicRDF reconstruction and advected droplet on the wall.
 
 - [ ] Check the Droplets conference - there was a contribution for interFoam or interIsoFoam with wetting in IJMF (!)