[FEM] Elmer: push mesh scaled to Elmer

- reverts commit d296732d - the scaling it correct
- there is a bug in Elmer that the heat source is not aware of the scaling
- write the scaling directly to the solver, not to the mesh itself. (make in principal no difference but we are closer to the solver)

src/Mod/Fem/femsolver/elmer/tasks.py

@@ -252,6 +252,7 @@ class Results(run.Results):
             self.fail()
             return
         self.solver.ElmerResult.read(postPath)
+        self.solver.ElmerResult.scale(1000)
         self.solver.ElmerResult.getLastPostObject().touch()
         self.solver.Document.recompute()
 

src/Mod/Fem/femsolver/elmer/writer.py

@@ -311,12 +311,9 @@ class Writer(object):
     def _handleSimulation(self):
         self._simulation("Coordinate System", "Cartesian 3D")
         self._simulation("Coordinate Mapping", (1, 2, 3))
-        # not necessary anymore since we use SI units
-        # if self.unit_schema == Units.Scheme.SI2:
-        # self._simulation("Coordinate Scaling", 0.001)
-        #     Console.PrintMessage(
-        #         "'Coordinate Scaling = Real 0.001' was inserted into the solver input file.\n"
-        #     )
+        # Elmer uses SI base units, but our mesh is in mm, therefore we must tell
+        # the solver that we have another scale
+        self._simulation("Coordinate Scaling", 0.001)
         self._simulation("Simulation Type", "Steady state")
         self._simulation("Steady State Max Iterations", 1)
         self._simulation("Output Intervals", 1)