create more parameters for adjusting the mesh

openfoam/run/flowAroundCylinder/system/blockMeshDict

@@ -20,8 +20,17 @@ convertToMeters 0.01;  // centimetres.  According to https://cfd.direct/openfoam
 rx 3.5355339059327373;
 // = // rx #calc "5.0 / Foam::sqrt(2.0)";  // length of short side of rectangular triangle with long side =5
 
-arcNx #calc "50 * $N";
-arcNy #calc " 30 * $N";
+arcNx #calc "2 * $N";  // 2 so that   2 would be possible (used formerly for pipeNx)
+arcNy #calc "2 * $N";
+arcGradingX 0.2;
+// outer side has length 40  or 41),
+// inner length is 5 * pi/2, so inner cells must be 5 * pi / 2 / 40 times as big:
+// 0.1963, so 0.2 is close enough
+pipeNx #calc "3 * $arcNx";
+// is 4.5 times as long as first part around cylinder, but a lot less is happening
+pipeGrading 3;
+// should adjust grading in a way that there is no big size difference at boundary between square around cylinder and
+// pipe part
 
 thickness 100;    // in other files 0.5 = 50 cm = 50 is assumed to be a valid z coordinate (probes)
 
@@ -56,11 +65,11 @@ vertices
 
 blocks
 (
-      name arcl hex (Ftl Fbl Fcbl Fctl Btl Bbl Bcbl Bctl) ($arcNx $arcNy 1) simpleGrading (1 1 1)
-      name arct hex (Fts Ftl Fctl Fctr Bts Btl Bctl Bctr) ($arcNx $arcNy 1) simpleGrading (1 1 1)
-      name arcr hex (Fbs Fts Fctr Fcbr Bbs Bts Bctr Bcbr) ($arcNx $arcNy 1) simpleGrading (1 1 1)
-      name arcb hex (Fbl Fbs Fcbr Fcbl Bbl Bbs Bcbr Bcbl) ($arcNx $arcNy 1) simpleGrading (1 1 1)
-      name pipe hex (Fbs Fbr Ftr Fts Bbs Bbr Btr Bts) (#calc "9 * $arcNx / 2" $arcNx 1) simpleGrading (1 1 1)
+      name arcl hex (Ftl Fbl Fcbl Fctl Btl Bbl Bcbl Bctl) ($arcNx $arcNy 1) simpleGrading (1 $arcGradingX 1)
+      name arct hex (Fts Ftl Fctl Fctr Bts Btl Bctl Bctr) ($arcNx $arcNy 1) simpleGrading (1 $arcGradingX 1)
+      name arcr hex (Fbs Fts Fctr Fcbr Bbs Bts Bctr Bcbr) ($arcNx $arcNy 1) simpleGrading (1 $arcGradingX 1)
+      name arcb hex (Fbl Fbs Fcbr Fcbl Bbl Bbs Bcbr Bcbl) ($arcNx $arcNy 1) simpleGrading (1 $arcGradingX 1)
+      name pipe hex (Fbs Fbr Ftr Fts Bbs Bbr Btr Bts) ($pipeNx $arcNx 1) simpleGrading ($pipeGrading 1 1)
 );
 
 edges