Wavemaker motion from file
==========================

HOS-NWT enables the possibility to use an arbitrary wavemaker mtion described with specific files. This is available from the input file of HOS-NWT ``input_HOS-NWT.dat`` with the parameter ``icase`` (``file_name`` is the wavemaker file name)

-  icase=3 - *file_name.dat* describes the frequency components of linear waves generated by wavemaker and *file_name.cfg* describes the configuration of wavemaker
-  icase=31 - *file_name.txt* is an output of control software used in ECN Wave Basin
-  icase=32 - *file_name.txt* is an output of control software used in ECN Towing Tank
-  icase=33 - *file_name.txt* is an output of control software used in other tanks

.. _cfg-and-dat-file-icase3:

.cfg and .dat file (icase=3)
----------------------------

This is the basic description of wavemaker motion using file. The HOS-NWT's user has to give two files described hereafter

-  ``file_name.cfg``: describes the wavemaker configuration. One value per line (real value unless specified):

   -  ``rnum`` is an integer
   -  ``clock`` defines the clockrate (Hz) of the wavemaker motion

      -  Previous parameters define frequency spacing df = clock/2\ :sup:`rnum`

   -  ``depth`` is the depth (in m) of the wave tank
   -  ``ramp`` defines length of time ramp in number of cycles (i.e. ramp = Tramp*clock) (useless for now, uses ``input_HOS-NWT.dat`` information)
   -  ``typ_ramp`` [characters], defines type of ramp, use ``lin`` (useless for now uses ``input_HOS-NWT.dat`` information)
   -  ``cutoff_low`` defines the low frequency cut-off (Hz)
   -  ``cutoff_high`` defines the high frequency cut-off (Hz)
   -  ``Ly`` gives the beam of the wave tank (in m)
   -  ``typ_wmk`` [characters], choose between: ``hinged`` and ``piston``
   -  ``hinge`` defines for hinged wavemaker the rotation axis distance (>= 0, in m)

-  ``file_name.dat`` gives the frequency description of **linear waves generated by wavemaker motion** (i.e. in frequency domain this is the wavemaker motion multiplied by transfer function of the chosen wavemaker ; note that no additional phase shift is applied (this is the wave at x=0)). Each line corresponds to a frequency and should contain (separated with commas)

   -  ``n_harmo`` [integer]: number of present harmonic (i.e. f=n_harmo*df)
   -  ``f``: frequency (f=n_harmo*df) (in Hz)
   -  ``ampli``: amplitude of the component (in m)
   -  ``angle``: angle of the component (deg)
   -  ``phase``: phase of the component (rad) [-π ; π]

.txt file (icase=31, 32 or 33)
------------------------------

This configuration is specific to the wave tanks of Ecole Centrale Nantes (ocean wave basin or towing tank) or tanks using same control software of wavemaker motion. The wavemaker motion control software developed by Edinburgh Designs Limited allows a specific output under ``.txt``\ file format which may be given as input to HOS-NWT. This way, the reproduction of an experiment conducted in those tanks is straightforward, using the exact same wavemaker motion in physical wave basin and the Numerical Wave Tank.