From 2c08067a59934b0c71ec02a8f98cf23f88646efa Mon Sep 17 00:00:00 2001
From: graham <g.macpherson@opencfd.co.uk>
Date: Mon, 1 Nov 2010 17:09:25 +0000
Subject: [PATCH] ENH:  Auto and limited min cell size for
 densityWeightedStochastic.

---
 .../densityWeightedStochastic.C               | 24 +++++++++++++++----
 .../densityWeightedStochastic.H               | 14 +++++++----
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.C b/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.C
index 0e9b3beab4..8dd5c71e96 100644
--- a/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.C
+++ b/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.C
@@ -51,9 +51,13 @@ densityWeightedStochastic::densityWeightedStochastic
 :
     initialPointsMethod(typeName, initialPointsDict, cvMesh),
     totalVolume_(readScalar(detailsDict().lookup("totalVolume"))),
-    maxDensity_
+    minCellSize_
     (
-        1.0/pow3(readScalar(detailsDict().lookup("minCellSize")))
+        detailsDict().lookupOrDefault<scalar>("minCellSize", GREAT)
+    ),
+    minCellSizeLimit_
+    (
+        detailsDict().lookupOrDefault<scalar>("minCellSizeLimit", 0.0)
     )
 {}
 
@@ -76,6 +80,8 @@ std::vector<Vb::Point> densityWeightedStochastic::initialPoints() const
 
     label trialPoints = 0;
 
+    scalar maxDensity = 1/pow3(max(minCellSize_, SMALL));
+
     while (volumeAdded < totalVolume_)
     {
         trialPoints++;
@@ -91,10 +97,19 @@ std::vector<Vb::Point> densityWeightedStochastic::initialPoints() const
 
         scalar localSize = cvMesh_.cellSizeControl().cellSize(p);
 
+        if (localSize < minCellSize_)
+        {
+            minCellSize_ = max(localSize, minCellSizeLimit_);
+
+            // 1/(minimum cell size)^3, gives the maximum permissible point
+            // density
+            maxDensity = 1/pow3(max(minCellSize_, SMALL));
+        }
+
         scalar localDensity = 1/pow3(max(localSize, SMALL));
 
         // Accept possible placements proportional to the relative local density
-        if (localDensity/maxDensity_ > rndGen.scalar01())
+        if (localDensity/maxDensity > rndGen.scalar01())
         {
             // Determine if the point is "wellInside" the domain
             if
@@ -116,7 +131,8 @@ std::vector<Vb::Point> densityWeightedStochastic::initialPoints() const
     Info<< nl << "    " << typeName << " - "
         << trialPoints << " locations queried ("
         << scalar(initialPoints.size())/scalar(trialPoints)
-        << " success rate)" << endl;
+        << " success rate).  minCellSize " << minCellSize_
+        << endl;
 
     return initialPoints;
 }
diff --git a/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.H b/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.H
index d345fa4578..8cc1afc0cb 100644
--- a/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.H
+++ b/src/mesh/conformalVoronoiMesh/initialPointsMethod/densityWeightedStochastic/densityWeightedStochastic.H
@@ -25,6 +25,8 @@ Class
     Foam::densityWeightedStochastic
 
 Description
+    Choose random points inside the domain and place them with a probability
+    proportional to the target density of points.
 
 SourceFiles
     densityWeightedStochastic.C
@@ -44,7 +46,7 @@ namespace Foam
 {
 
 /*---------------------------------------------------------------------------*\
-                 Class densityWeightedStochastic Declaration
+                   Class densityWeightedStochastic Declaration
 \*---------------------------------------------------------------------------*/
 
 class densityWeightedStochastic
@@ -59,9 +61,13 @@ private:
         //- The total volume to be filled
         scalar totalVolume_;
 
-        //- 1/(minimum cell size)^3, gives the maximum permissible point
-        //  density
-        scalar maxDensity_;
+        //- Working variable for minimum cell size, a starting value may be
+        //  specified in the dictionary
+        mutable scalar minCellSize_;
+
+        //- Smallest minimum cell size allowed, i.e. to avoid high initial
+        //  population of areas of small size
+        scalar minCellSizeLimit_;
 
 
 public: