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.
Installation steps to create the executable program are similar to the ones of the main program. Particularly, note that same library is used for Fast Fourier Transforms (FFTW) with identical linking.
A Makefile is provided with the source code for compiling PostProcessing in Linux/Unix environment. The GNU Fortran compiler gfortran shall be used. Other Fortran compilers may be used with small adjustments of compiler options, libraries...
Makefile makes use of executable makedepf90 to extract automatic dependencies available here
Description of compilation, linking... with Windows environment will be completed later.
The input file has the following form and is assumed to be named input_post_process.dat
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i_carddefines 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.
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T_startgives the time of the beginning of post-processing -
T_stopgives the time of the end of post-processing
This section of input file describes the mesh of the output of velocity and pressure card:
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x_minis the minimum of the x-mesh -
x_maxis the maximum of the x-mesh -
y_minis the minimum of the y-mesh (for 3D simulation) -
y_maxis the maximum of the y-mesh (for 3D simulation) -
z_minis the minimum of the z-mesh -
z_maxis the maximum of the z-mesh (for i_card = 1) -
i_zvectis the number of points to describe z vector
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tecplotgives the tecplot version of output files -
file_modgives the name of file of modal amplitudes of volumic informations (with possible relative path)
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:
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data_VP_card.datgives useful informations about the card created inVP_card.dat. This is used at ECN as coupling informations file. (i_card=1) -
VP_card.datcontains 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.datcontains 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 at ECN for coupling between HOS and RANS solver with the SWENS method (Spectral Wave Explicit Navier-Stokes). The quantities to reconstruct have to be adapted for the problem solved but the core is the one proposed in this post-processing routines.
We refer to the following publications for details about the SWENS coupling strategy
- Monroy, C., Ducrozet, G., Bonnefoy, F., Babarit, A., Gentaz, L., Ferrant, P., RANS Simulations of a calm buoy in regular and irregular seas using the SWENSE method, International Journal of Offshore and Polar Engineering, Vol. 21, No 4, 264-271, 2011.
- Luquet, R., Gentaz, L., Ferrant, P., Alessandrini, B., Viscous flow simulation past a ship in waves using the SWENSE approach, 25th Symposium on Naval Hydrodynamics, St. John’s, Canada, 2004
- Ferrant, P., Gentaz, L., Alessandrini, B., Le Touzé, D., A potential / RANSE approach for regular water wave diffraction about 2D structures, Ship Technology Research, Vol. 50, No 4, 2003.