Shifting towards constant number of particles per edge

So now each edge has the same number of particles and the weight of each
particle is calculated based on the surface of each edge compared to the
total one.

Only in 2DCyl, still to extend to other geometries.

Not perfect constant density, but the issue might be the node volume.

src/modules/moduleInject.f90

@@ -63,6 +63,7 @@ MODULE moduleInject
     INTEGER, ALLOCATABLE:: edges(:) !Array with edges
     REAL(8), ALLOCATABLE:: cumWeight(:) !Array of cummulative probability
     REAL(8):: sumWeight
+    REAL(8):: surface ! Total surface of injection
     TYPE(velDistCont):: v(1:3) !Velocity distribution function in each direction
     CONTAINS
       PROCEDURE, PASS:: init         => initInject
@@ -164,15 +165,12 @@ MODULE moduleInject
 
       END DO
 
-      !Calculates cumulative probability
-      ALLOCATE(self%cumWeight(1:self%nEdges))
-      et = 1
-      self%cumWeight(1) = mesh%edges(self%edges(et))%obj%weight
-      DO et = 2, self%nEdges
-        self%cumWeight(et) = mesh%edges(self%edges(et))%obj%weight + self%cumWeight(et-1)
+      !Calculates total area
+      self%surface = 0.D0
+      DO et = 1, self%nEdges
+        self%surface = self%surface + mesh%edges(self%edges(et))%obj%surface
 
       END DO
-      self%sumWeight = self%cumWeight(self%nEdges)
 
     END SUBROUTINE initInject
 
@@ -313,12 +311,12 @@ MODULE moduleInject
 
       !$OMP DO
       DO n = nMin, nMax
-        randomX    =  randomWeighted(self%cumWeight, self%sumWeight)
+        randomX    =  random(1, self%nEdges)
         randomEdge => mesh%edges(self%edges(randomX))%obj
         !Random position in edge
         partInj(n)%r = randomEdge%randPos()
         !Assign weight to particle.
-        partInj(n)%weight = self%species%weight
+        partInj(n)%weight = self%species%weight * randomEdge%surface / self%surface
         !Volume associated to the edge:
         IF (ASSOCIATED(randomEdge%e1)) THEN
           partInj(n)%cell = randomEdge%e1%n