Merge pull request #2441 from TomFischer/DocuBCsMotivation

[web] Add documentation for boundary handling tools.

web/config.toml

@@ -123,16 +123,21 @@ staticDir = ["dist", "static"]
   weight = 1
 
 [[menu.tools]]
-  name = "Meshing"
+  name = "Meshing: Bulk meshes"
   identifier = "meshing"
   weight = 2
 
+[[menu.tools]]
+  name = "Meshing: Subdomains"
+  identifier = "meshing-submeshes"
+  weight = 3
+
 [[menu.tools]]
   name = "Model Preparation"
   identifier = "model-preparation"
-  weight = 3
+  weight = 4
 
 [[menu.tools]]
   name = "Workflows"
   identifier = "workflows"
-  weight = 4
+  weight = 5

web/content/docs/tools/model-preparation/constructMeshesFromGeometry/index.pandoc → web/content/docs/tools/meshing-submeshes/constructMeshesFromGeometry/index.pandoc

@@ -5,7 +5,7 @@ author = "Dmitri Naumov"
 
 [menu]
   [menu.tools]
-    parent = "model-preparation"
+    parent = "meshing-submeshes"
 +++
 
 ## General

web/content/docs/tools/meshing/extract-surface/index.pandoc → web/content/docs/tools/meshing-submeshes/extract-surface/index.pandoc

@@ -5,7 +5,7 @@ author = "Thomas Fischer"
 
 [menu]
   [menu.tools]
-    parent = "meshing"
+    parent = "meshing-submeshes"
 +++
 
 ## General

web/content/docs/tools/model-preparation/identifySubdomains/index.pandoc → web/content/docs/tools/meshing-submeshes/identifySubdomains/index.pandoc

@@ -5,7 +5,7 @@ author = "Dmitri Naumov"
 
 [menu]
   [menu.tools]
-    parent = "model-preparation"
+    parent = "meshing-submeshes"
 +++
 
 ## General

web/content/docs/tools/meshing-submeshes/submeshes/index.pandoc

++++
+date = "2019-03-19T09:56:57+01:00"
+title = "Submeshes for Boundary Conditions, Source Terms, and Flux Calculations"
+author = "Thomas Fischer"
+weight = 1
+
+[menu]
+  [menu.tools]
+    parent = "meshing-submeshes"
++++
+
+## Motivation
+
+Boundary conditions are defined on the boundary of a given domain. Source terms
+may exist on subdomains of the domain. Sometimes the flux across a subdomain
+is interesting for the modeller.
+
+Consequently, we need a way to specify such subdomains for the Finite Element
+simulation. There are several possibilities to define a subdomain. One
+possibility is to use a geometry via a gli- or gml-file. Since the geometry
+often doesn't match exactly on the domain mesh, one has to specify a search
+radius to find nodes, elements, or faces in the neighborhood of the geometry.
+It can be difficult to find an appropriate search readius for adaptive refined
+domain meshes. Finally, with the geometry and a suitable search radius the
+associated domain elements and domain nodes are searched for. Since this happens
+during the simulation, this approach is not very robust.
+
+Another possibility, avoiding the search during the simulation and thus more
+robust, is to precompute the subdomains as meshes. These precomputed subdomains
+are now passed to the OGS-6 simulator in the same format as the bulk mesh, the
+vtu format. The subdomains additionaly contain information to identify the
+corresponding bulk mesh entities like nodes, elements and faces of elements.
+
+### A simple example
+
+In the next figures it is explained how a boundary condition can be set to the
+top surface of a quad domain for a OGS-6 simulation. The first figure depicts
+the bulk mesh and the id's of the nodes on the top.
+![](01_bulk_mesh_with_top_node_ids.png)
+The differently coloured top surface mesh can be obtained for instance by the
+[ExtractSurface]({{< ref "extract-surface" >}}) tool.
+![](02_bulk_mesh_top_surface.png)
+For visualisation purposes the top surface is translated upwards. The picture
+shows the bulk mesh and the id's of the nodes on the top of it. Furthermore,
+the translated top surface mesh with the corresponding bulk node id's are
+represented.
+![](03_bulk_mesh_with_ids_top_surface_bulk_node_ids.png)
+

web/content/docs/tools/workflows/create-a-simple-parallel-model/index.pandoc

@@ -48,13 +48,13 @@ boundary conditions and parallelization boundary mesh files are needed. There
 are two possibilities to create such files:
 
  - If there is a `.gml` file, use [`constructMeshesFromGeometry`
-   tool]({{<ref "../model-preparation/constructMeshesFromGeometry">}})  which
+   tool]({{<ref "../meshing-submeshes/constructMeshesFromGeometry">}})  which
    takes the mesh file and geometry and creates all the boundaries which are
    named in the `.gml` file with the required `bulk_node_ids` and
    `bulk_element_ids` mappings.
  - If there is a boundary mesh (generated by gmsh or salome, or extracted in
    paraview, for example) use the [`identifySubdomains`
-   tool]({{<ref "../model-preparation/identifySubdomains">}}) to create or
+   tool]({{<ref "../meshing-submeshes/identifySubdomains">}}) to create or
    verify the needed `bulk_node_ids` and `bulk_element_ids` mappings.
 
 ## Partition the mesh