.. _comflow_library:

ComFLOW as static library
===================================

The ComFLOW subroutines have also been linked into a library so they can be linked
to and used by other external programs. Different versions of the ComFLOW library are available
on both Linux and Windows. In this section it is assumed that one of the available library
versions in the subdirectory ``lib`` has been selected for coupling and that it has been renamed to ``comflow.lib``.

An example of an application is the effect of sloshing in cargo tanks on ship motions.
The ComFLOW library has been coupled to the MARIN ship motion program aNySIM.
ComFLOW determines the internal sloshing loads and aNySIM determines the ship
motions due to these sloshing loads and other external forces (incoming waves),
see :cite:`bunnik2010modelling`.

Getting started
----------------

The library ``comflow.lib`` has been compiled with the Intel Fortran compiler,
in double precision and with OpenMP support.
The library can be coupled to the user's program
by any available Fortran compiler, preferably
the Intel Fortran compiler (``ifort``).

* For the coupling under Linux: when ``myprog.f`` contains the external program of the user,
  type at the command prompt:

  .. code-block:: bash

     ifort -double-size 64 -real-size 64 -openmp myprog.f
                                         comflow.lib -o myprog.out

  As a result, the coupled executable ``myprog.out`` is created.
* For the coupling under Windows, type at the command
  prompt in a DOS window

  .. code-block:: batch

     ifort /double-size:64 /real-size:64 /Qopenmp myprog.f
                                       comflow.lib /exe:myprog.exe

  As a result the coupled executable ``myprog.exe`` is created.

The subroutines that are available to external programs are given below.
All underlying subroutines, called by these subroutines,
are also available in the library.
The subroutines only have to be called, they cannot be modified.
The required subroutines are:


Available subroutines
----------------------------------------

.. note::

   *Still to come.*


An example
---------------------------

The example given below shows how to move a sloshing tank in ComFLOW with a user-written program
and how to obtain the sloshing loads.
In the example, the motion of the sloshing tank is prescribed in the external program.
The geometry of the sloshing tank has to described in the input file ``${INPUT}/geometry.in`` (see :numref:`geometry_definition`)
and the simulation is further controlled with ``${INPUT}/comflow.in`` (see :numref:`Chapter % s <fixed_form_input>`).
Note that the option ``motionframe`` should be set to 2 (see :numref:`fixed_form_input/moving_frame`).

The example shown below is also included in the ComFLOW distribution and can be found in the folder |COMFLOW_EXAMPLES_DIR|.

.. code-block:: fortran

  !
        program move_sloshing_tank
  !
        implicit none
  !
        integer*4 i,boxnr,tcycle
        real*8  force(3),moment(3),inertia(3)
        real*8  t,tmax,dt,t_next
        real*8  pos(6),velocity(6),acceleration(6)
        real*8  moment_location(3)

  !     run GEODEF
        call initialize(1)  !<-- 1=GEODEF
        call setup          !<-- process input files
        call geoliq         !<--
        call closure        !<-- clean up

  !     now run ComFLOW
        call initialize(0)  !<-- 0=COMFLOW
        call setup          !<-- process input files
  !
        pos = 0.0
        velocity = 0.0
        acceleration = 0.0
        ! pre-compute the tank motions, velocities and accelerations
        do i=0,1002
          t_next = i*0.01
          pos(2) = 0.1*sin(4.0*t_next)
          velocity(2) = 0.1*4.*cos(4.0*t_next)
          acceleration(2) = -0.1*16.0*sin(4.0*t_next)
          call set_moving_frame(t_next, pos, velocity, acceleration)
        enddo
  !
        boxnr = 1
        moment_location = 0.0
  !
        call get_time(tcycle,t,tmax,dt)
        ! start time loop
        do while (t < tmax)
  !
           ! carry out a timestep
           call loop
           call get_time(tcycle,t,tmax,dt)
  !
           ! obtain the forces on the tank
           call get_force_frcbx(boxnr,force,moment,inertia, moment_location)
        enddo
  !
        call closure        !<-- clean up again
  !
        end program
  !



.. .. rubric:: Footnotes



.. .. rubric:: References

.. .. bibliography:: references.bib