FlowDepthSolver

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Name of the source code file: Flowdepth.f90
Name of contained subroutine(s): FlowdepthSolver
Name(s) of contained function(s): ---

Description of FlowdepthSolver:
This solver computes the vertical distance from a surface (either free surface or bedrock in Glaciology). In structured FD-grids this is a trivial procedure - not so in unstructured FEM meshes as used by Elmer. A degenerated Poisson equation has to be solved in order to get nodal values for either the flow depth below the free surface or the flow height above the bedrock.

Keywords of FlowdepthSolver:

! This solves the depth underneath the free surface
!--------------------------------------------------
Solver 1
  Equation = "Flowdepth"
   Exec Solver = "Before Timestep"
   Procedure = File "Flowdepth" "FlowDepthSolver"
   Variable = String "Depth"
   Variable DOFs = 1
   Linear System Solver = "Iterative"
   Linear System Max Iterations = 100
   Linear System Convergence Tolerance = 1.0E-09
   Linear System Abort Not Converged = False ! mostly not essential
   Linear System Preconditioning = "ILU0"
   Linear System Residual Output = 1
   ! this sets the direction
   ! -1 is negative z-direction (upside down)
   ! +1 is positive (downside up)
   Gradient = Real -1.0E00
  ! switch that to True, if you
  ! want to have free surface gradients
  ! to be computed
  !------------------------------------
  Calc Free Surface = Logical True
  ! the name for the exported (if not existing) added variable
  ! the gradients will be stored in variables with the base
  ! name given and "Grad1" and (in 3 dimensions) "Grad2" added,
  ! so in our case "FreeSurfGrad1" and "FreeSurfGrad2"
  ! again, if those variables did not exist, they will be
  ! automatically created
  !-----------------------------------------------------------
  Freesurf Name = String "FreeSurf"
End

! This solves the height above the bedrock
!------------------------------------------
Solver 2
  Equation = "Flowheight" ! mind different name
  Exec Solver = "Before Timestep"
  Procedure = File "Flowdepth2" "FlowDepthSolver" ! make a copy of the original solver, to get a separate address space
  Variable = String "Height" ! mind different name for variable
  Variable DOFs = 1
  Linear System Solver = "Direct"
  Linear System Direct Method = "UMFPACK"
  Linear System Convergence Tolerance = 1.0E-09
  Linear System Abort Not Converged = False
  Gradient = Real 1.0E00 ! this time positive
  Calc Free Surface = Logical False
End

! boundary at the free surface
!-----------------------------
Boundary Condition 1
  ...
  Depth = Real 0.0
End

! boundary at bedrock
!-----------------------------
Boundary Condition 2
  ...
  Height = Real 0.0
End

! internal boundary with
! no Dirichlet and neither
! the default Neumann 
! condition
!-----------------------------
Boundary Condition 3
  ...
  Skip Flowdepth = Logical True
End
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