sink_particle.md edited online with Bitbucket

Comments on JP's accretion suggestions.

doc/manual/sink_particle.md

@@ -81,10 +81,11 @@ Make is possible for the particle to accrete momentum in addition to mass, and t
 Create sink particles dynamically and allow the presence of multiple sinks. 
 
 
-Suggestion writen by JP: 
+### Suggestion writen by JP: 
+
+Add to ```acc/mhd_solver/stencil_defines.h```:
 
 ```
-add to acc/mhd_solver/stencil_defines.h:
     // Scalar mass
     #define AC_FOR_USER_REAL_PARAM_TYPES(FUNC) \
                 ...
@@ -100,14 +101,19 @@ add to acc/mhd_solver/stencil_defines.h:
                 ...
                 ...
                 FUNC(AC_sink_particle_pos),
+```
+Currently we do not do it like that as AcReal3 constant parameter. However, would be good thing to implement eventually. 
+```
 
     // Vertex buffer for accretion
     #define AC_FOR_VTXBUF_HANDLES(FUNC) \
                 ...
                 FUNC(VTXBUF_ACCRETION),
+```
 
+Add to ```acc/mhd_solver/stencil_process.sps```:
 
-acc/mhd_solver/stencil_process.sps:
+```
 
     Scalar
     your_accretion_function(int3 globalVertexIdx)
@@ -118,6 +124,10 @@ acc/mhd_solver/stencil_process.sps:
         
         return *accretion from the current cell at globalVertexIdx*
     }
+    
+```
+This step will require that we calculate the acctetion as **mass** in a grid cell volume. This is to eventually take an advantage of nonunifrorm grid. OIOn that way we do not need to worry about it in the collective operation stage. 
+```
 
     // This should have a global scope
     out Scalar out_accretion = VTXBUF_ACCRETION;
@@ -130,9 +140,12 @@ acc/mhd_solver/stencil_process.sps:
 
         out_accretion = your_accretion_function(globalVertexIdx);            
     }
+```
+Important to note that we need to take into account the reduction of density with other equations of motion. Or apply analogous style to forcing.  
 
+Create new file ```src/standalone/model/host_accretion.cc```:
 
-src/standalone/model/host_accretion.cc: <- new file
+```
     #include "astaroth.h"
 
     void
@@ -146,10 +159,12 @@ src/standalone/model/host_accretion.cc: <- new file
         info->real_params[AC_sink_particle_mass] = mass; // Save for the next iteration
         acLoadDeviceConstant(AC_sink_particle_mass, mass); // Load to the GPUs
     }
+```
+We assume that acReduceScal will sum up the mass in the accretion buffer. 
 
+Call from```src/standalone/simulation.cc```:
 
-src/standalone/simulation.cc:
-    
+```    
     #include "model/host_accretion.h"
     
     int