HOS-NWT

Numerical Wave Tank based on High-Order Spectral method

This README file describes the different cases that might be computed with HOS-NWT and gives instructions to set the numerical parameters n1 to p2.

Setting the value of integers n1, n2, M, p1 and p2 in common_vars.f90

2D simulation

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)

## 3D simulation

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)

input_HOS-NWT.dat will have to be attached to run this program.

Setting the value of integer icase in input_HOS-NWT.dat

• icase = 1 : Sloshing case Computation starts with a natural mode of the tank (in x) of a given amplitude

• icase = 2 : Monochromatic case Regular wave is generated in the NWT User defines frequency, amplitude, phase (and angle of propagation if 3D simulation)

• icase = 3 and 31 and 32 and 33 : File case Wavemaker movement is deduced from input file named 'filename'

  • 3 - filename.cfg describes the configuration of wavemaker filename.dat describes the frequency components of wavemaker movement
  • 31 - filename.txt is an output of control software used in ECN Wave Basin
  • 32 - filename.txt is an output of control software used in ECN Towing Tank
  • 33 - filename.txt is an output of control software used in other tanks

• icase = 4 and 41 : Irregular wave Wavemaker movement creates an irregular wave field with a given Hs and Tp

  • 4 - JONSWAP spectrum
  • 41 - Bretschneider spectrum

Further details about input file, output of the code... may be find at the Wiki page of HOS-NWT project: https://github.com/LHEEA/HOS-NWT/wiki

Solution method

Numerical tools

1. Fully FFT resolution for spectral and additionnal modes. 1.1. Fully nonlinear HOS for free surface 1.2. 1st, 2nd and 3rd order wavemaker modeling
2. Runge-Kutta 4th-order scheme in time.

Coordinates system

^ Y (the width of wave tank)
|
|
O ---------> X (the length of wave tank)

Discretization of wave field

Y ^  eta(1,n2) eta(2,n2) --------------- eta(n1,n2)
  |    .         .                          .
  |    .         .                          .
  |  eta(1,3)    .                          .
  |  eta(1,2)  eta(2,2) ----------------- eta(n1,2)
  |  eta(1,1)  eta(2,1) eta(3,1) -------- eta(n1,1)
  0 -------------------------------------------> X

Nondimensionalizations

[L] = h
[T] = 1/sqrt(g/h)