Post-processing

The post-processing of outputs of HOS-NWT is available in sources/PostProcessing directory. This is written as a program to compile and execute with a given input file named input_post_process.dat containing necessary informations and described hereafter. The installation procedure is available in Getting started section. The following commands can be executed:

  • Linux environment (in a terminal):

./HOS-NWT-PostProcessing input_post_process.dat

  • Windows environment (using the standard command prompt cmd):

HOS-NWT-PostProcessing.exe input_post_process.dat

Input file

The input file has the following form and is assumed to be named input_post_process.dat

--- Choice of post-processing options
VP-card output               :: i_card           :: 2
Starting time analysis       :: T_start          :: 0.0
Stoping time analysis        :: T_stop           :: 0.40
--- Velocities/pressure cards
Minimum x in VP-card         :: x_min            :: 0.0
Maximum x in VP-card         :: x_max            :: 50.0
Minimum y in VP-card         :: y_min            :: 0.0
Maximum y in VP-card         :: y_max            :: 10.0
Minimum z in VP-card         :: z_min            :: -5.0
Maximum z in VP-card         :: z_max            :: 0.5
Number of points in z        :: i_zvect          :: 20
--- Input files
Tecplot version              :: tecplot          :: 11
Name of modal description    :: file_mod         :: Results/modes_HOS_SWENSE.dat

Choice of post-processing options

  • i_card defines the output of velocity and pressure cards (i_card /= 0)

    • i_card = 1 : Mesh is defined with constant z and (x,y) from HOS-NWT simulation. This is the most efficient way to generate cards or for coupling since it allows use of FFTs

    • i_card = 2 : Mesh is defined with boundary (free-surface) fitted z and (x,y) from HOS-NWT simulation.

  • T_start gives the time (in s) of the beginning of post-processing

  • T_stop gives the time (in s) of the end of post-processing

Velocities/pressure cards

This section of input file describes the mesh of the output of velocity and pressure card:

  • x_min is the minimum (in m) of the x-mesh

  • x_max is the maximum (in m) of the x-mesh

  • y_min is the minimum (in m) of the y-mesh (for 3D simulation)

  • y_max is the maximum (in m) of the y-mesh (for 3D simulation)

  • z_min is the minimum (in m) of the z-mesh

  • z_max is the maximum (in m) of the z-mesh (for i_card = 1)

  • i_zvect is the number of points to describe z vector

Input files

  • tecplot gives the tecplot version of output files (default 11)

  • file_mod gives the name of file of modal amplitudes of volumic informations (with possible relative path)

Description of kinematics inside fluid domain i_card ≠ 0

HOS-NWT is able to create a modal description of some volumic informations in the fluids. All necessary informations to compute velocities, pressure, acceleration (or whatever derivatives of these quantities) are included in this file usually named modes_HOS_SWENSE.dat

We give as an example of treatment of this file the possibility to create representation of velocities and pressure field (i_card /= 0). Depending on the choice of user following files are created:

  • data_VP_card.dat gives useful informations about the card created in VP_card.dat. This is used at ECN as coupling informations file. (i_card=1)

  • VP_card.dat contains the velocities and pressure card in the case i_card=1, i.e. when the mesh is at constant z. This file is adapted to Tecplot visualization.

  • VP_card_fitted.dat contains the velocities and pressure card in the case i_card=2, i.e. when a boundary fitted (free surface) mesh is used. This file is adapted to Tecplot visualization.

Note that the process used to create those cards is similar to the one used for coupling between HOS and CFD solver (see the dedicated package for coupling Grid2Grid).

We refer to Ferrant et al. [2003], Luquet et al. [2004], Choi et al. [2017], Li et al. [2021], Kim et al. [2024] for details about the coupling strategy.