Simulation Setup

Tolosa-lct shares the same input system as Tolosa-sw. This page documents the additions and differences specific to Tolosa-lct (Leucothea).

Directory Layout

All simulations run from the bin/ directory. You need to place there:

• input.txt — main configuration file
• The mesh file (.msh from Gmsh, or generated from Cartesian parameters)
• m_user_data.f90 — Fortran submodule defining bathymetry and initial conditions (recompiled at each run)
• Any required external forcing or boundary files (see External Input Files)

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Setting Up input.txt

All parameters have sensible defaults. A minimal input.txt for a non-hydrostatic Gmsh simulation:

mesh_name   = mymesh.msh
simu_time   = 12 hours
mach        = 0.2
cfl         = 0.5
w_vtk       = 1000000
dt_vtk      = 10 minutes

The key addition over Tolosa-sw is the mach parameter, which sets the acoustic speed for the NH splitting. A Cartesian mesh example:

nx          = 200
ny          = 100
lx          = 100000.
ly          = 50000.
bc_N        = wall
bc_S        = wall
bc_W        = neumann
bc_E        = wall
simu_time   = 6 hours
mach        = 0.2

See the complete parameter reference for all available parameters, and Boundary Conditions for the full BC type catalogue.

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Setting Up m_user_data.f90

m_user_data.f90 defines the problem geometry and initial conditions. It is a Fortran submodule of m_Tolosa_lct and is recompiled at every run (make mrun). It must implement:

Procedure	Role
user_parameters(dof, input, mesh)	called once before all initializations; read custom parameters, precompute data, open files
bathy_user(x, y)	return bathymetry (positive upward) at point (x, y)
h0_user(x, y, b)	return initial water depth at (x, y) given bathymetry b
u0_user(x, y)	return initial x-velocity at (x, y)
v0_user(x, y)	return initial y-velocity at (x, y)
w0_user(x, y)	return initial vertical velocity at (x, y)
p0_user(x, y)	return initial NH pressure at (x, y)
bc_user(tag, x, y, b)	return boundary value for a given named tag

The minimal skeleton (all functions returning 0 except bathymetry):

SUBMODULE (m_Tolosa_lct) m_user_data

   implicit none

CONTAINS

   MODULE SUBROUTINE user_parameters( dof , input , mesh )
      type(unk), intent(inout) :: dof
      type(cli), intent(inout) :: input
      type(msh), intent(inout) :: mesh
   END SUBROUTINE user_parameters

   MODULE real(rp) FUNCTION bathy_user( x , y )
      real(rp), intent(in) :: x , y
      bathy_user = -10._rp   ! flat bottom at -10 m
   END FUNCTION bathy_user

   MODULE real(rp) FUNCTION h0_user( x , y , b )
      real(rp), intent(in) :: x , y , b
      h0_user = max( -b , 0._rp )
   END FUNCTION h0_user

   MODULE real(rp) FUNCTION u0_user( x , y )
      real(rp), intent(in) :: x , y
      u0_user = 0._rp
   END FUNCTION u0_user

   MODULE real(rp) FUNCTION v0_user( x , y )
      real(rp), intent(in) :: x , y
      v0_user = 0._rp
   END FUNCTION v0_user

   MODULE real(rp) FUNCTION w0_user( x , y )
      real(rp), intent(in) :: x , y
      w0_user = 0._rp
   END FUNCTION w0_user

   MODULE real(rp) FUNCTION p0_user( x , y )
      real(rp), intent(in) :: x , y
      p0_user = 0._rp
   END FUNCTION p0_user

   MODULE real(rp) FUNCTION bc_user( tag , x , y , b )
      character(len=*), intent(in)           :: tag
      real(rp)        , intent(in), optional :: x , y , b
      bc_user = 0._rp
   END FUNCTION bc_user

END SUBMODULE m_user_data

user_parameters — the Setup Hook

Called after the mesh is loaded and input.txt parsed, but before bathymetry, BCs, initial state, friction, forcings, and numerical schemes are initialized. Use it to:

• Declare custom input.txt parameters via input%add_get:

  call input%add_get( 'h_0'     , default='1.d3' , kind=rtype , value=h_0     )
  call input%add_get( 'n_bathy' , default='1000' , kind=itype , value=n_bathy )

• Precompute geometry using globals: lx, ly, mesh%nc, proc/np, g, pi, pathto()
• Read/write auxiliary binary files:

  open( unit=new_unit(unit), file=pathto('bathy.bin'), form='unformatted', ... )

• Generate randomised fields using genrand(min, max) (from Tolosa-lib)

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Data Path

All file names in input.txt are resolved through pathto(), which prepends data_path (default "./") to any relative path.

Override at runtime:

./Tolosa_lct -data-path /path/to/data

Absolute paths are passed through unchanged.