Running HOS NWT - LHEEA/HOS-NWT GitHub Wiki

HOS-NWT has been developed for command-line run with an input file containing all specifications needed.

All output files will be created in a directory Results that has to be created before the run by the user.

At first, user has to set values of integers n1, n2, M, p1 and p2 in common_vars.f90

• For a 2D simulation,

  • Compile with n2=1 AND p2=1 to adjust the memory allocation to minimum

  • If partial dealiasing is used, compile with p1 set to maximal required value (total dealiasing is obtained with p1=M but it can be reduced if p1 is further set to a value below M

• For a 3D simulation,

  • Compile with n2=1 AND p2 set to required value

  • If partial dealiasing is used in x-direction, compile with p1 set to maximal required value (total dealiasing is obtained with p1=M but it can be reduced if p1 is further set to a value below M

  • If partial dealiasing is used in y-direction, compile with p2 set to maximal required value (total dealiasing is obtained with p2=M but it can be reduced if p2 is further set to a value below M

The input file has the following form and is assumed to be named input_HOS-NWT.dat

• xlen is the length (in m) of the wave tank
• ylen is the beam (in m) of the wave tank (useful only in 3D)
• h is the depth (in m) of the wave tank (constant)

• icase = 1 : Sloshing case

  • Computation starts with a natural mode of the tank (in x) of a given amplitude. It is defined by islosh and aslosh

• icase = 2 : Monochromatic case

  • Regular wave is generated in the NWT
  • User defines amplitude (amp_mono), frequency (nu_mono), phase (ph_mono)
  • 3D simulations uses in addition
    • theta_mono: the angle of propagation
    • ibat: the method used for directional wave generation. ibat=2 uses snake's principle and ibat=3 uses Dalrymple's method
    • xd_mono: uses the wave target distance for Dalrymple's method (ibat=3)

• icase = 3 and 31 and 32 and 33 : File case

  • Wavemaker movement is deduced from input file named 'file_name'
  • Fine description wavemaker motion description in input files may be found here
    • icase=3. - file_name.dat describes the frequency components of wavemaker movement 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
  • i_cut specifies if a frequency cut off is used (i_cut=1) or not. Latter is defined by low nuc_low and high nuc_high cut-off frequency

• icase = 4 and 41 : Irregular wave

  • Wavemaker movement creates an irregular wave field with a given H_s and T_p
    • 4. • JONSWAP spectrum with gammashape factor
    • 41. • Bretschneider spectrum
  • iseed defines the number used for random wave generation

• i_wmk defines the order of non-linearity used for the wavemaker (recommended value is i_wmk=2 but it may be 1,2 or 3)
• igeom defines the wavemaker vertical shape (1: piston, 2: hinged)
• d_hinge defines for hinged wavemaker the rotation axis distance (from bottom, d_hinge >= 0)
• iramp specifies the possible use of time ramp on wavemaker movement at beginning of simulation (iramp /= 0) and its shape (1: linear, 2: 2nd order polynom, 4: 4th order polynom)
• Tramp is the duration (in s) of the time ramp on wavemaker movement at beginning of simulation

• iabsnb defines the use (iabsnb=1) or not (iabsnb=0) of numerical beach at the end of the tank
• xabsf defines the location of the beginning of the numerical beach (ratio to the total length of wave tank)
• coeffabsf defines the absorption strength of the previously defined numerical beach

• iprobes defines the possible use (iprobes /= 0) of probes
• pro_file defines the file name of probes position: pro_file.inp
  • iprobes=1: free-surface probes, each line gives location x (and y in 3D)
  • iprobes=2: pressure probes, each line gives location x z (or x y z in 3D)

• T_stop is the duration (in s) of the simulation (and of the wavemaker movement)
• toler gives the tolerance of the adaptative Runge-Kutta scheme
• f_out gives the output frequency (in Hz)

Depending on the choices (0 to disable output) made in the input file (see above), different output files are created. They are created in a specific folder Results with a specific format dedicated to Tecplot visualization.

The parameter idim specifies if output are dimensional(=1) or nondimensional(=0).

• 3d.dat gives the 3D free surface quantities (η and φ^s) as function of time: i3d=1
• HOS_modes.dat gives the modal amplitudes of free surface quantities (η and φ^s) as function of time: imodes=1
• vol_energy.dat gives the temporal evolution of volume and energy
• wmk_motion.dat gives the wavemaker motion as function of time: iwmk=1
• probes.dat gives the free surface elevation at specific location given in file prob.inp: i_prob=1
• modes_HOS_SWENSE.dat gives the file containing modal information of volumic HOS field for visualization,physical interpretation of wavefield... or possible coupling between HOS and wave-structure interactions model for instance (SWENS method): see post-processing section: i_sw=1

Some input files examples are available in the Benchmark directory

For irregular wave motion (i.e. icase=3, 31, 32, 33, 4 or 41), the description of wavemaker motion is filtered above a cut-off limit of 4Hz. In usual test cases, this is not a problem since HOS-NWT is dedicated to the generation and propagation of gravity waves (no capillary effects taken into account): waves with frequencies higher than 4Hz could not be considered pure gravity waves. However, this may be changed in wavemaking_HOS.f90file for specific purpose.