What's new in SWAN 41.20AB
Feb 21, 2019
- The so-called observation-consistent wind input and white capping, known as the ST6 physics, is included as an option. In addition, dissipation of swell energy is also included. This ST6 package can be considered as an alternative to the Komen and Janssen formulations. Details on the ST6 physics are described in Rogers et al. (2012) and it is based on the work of Babanin, Young, Tsagareli, Ardhuin and others (see references therein).
New in SWAN 40.85 (Mar 23, 2012)
- Inclusion of parallel, unstructured mesh implementation utilizing the parallel infrastructure from ADCIRC.
- Inclusion of hooks for tightly coupled ADCIRC and SWAN models.
- New pre-defined curves for outputting: BOUNDARY, BOUND_01, BOUND_02, etc. See command CURVE in the User Manual.
- A new output quantity for TABLE and BLOCK: peak wave length named as LWAVP.
New in SWAN 40.81 (Mar 23, 2012)
- Wave damping due to vegetation (mangroves, salt marshes, etc.) at variable depths is included as an option. The calculation of this type of dissipation is specified by the drag coefficient, the stem diameter of plant (schematised as a cylinder), the number of plants per square meter and the vegetation height. In addition to the vertical variation, the possibility of horizontal variation of the vegetation characteristics is included as well. This inclusion enables the vegetation in a given region to be varied so as to reflect real density variations in the field.
New in SWAN 40.72 (Mar 23, 2012)
- The use of unstructured mesh in the geographical domain is included. The grid may be comprised of triangular cells only. The following grid generators are supported by SWAN:
- ADCIRC (use of the file fort.14 generated by SMS)
- Triangle
- Easymesh
- For the computation of the integral parameters (e.g. significant wave height, directional spreading, etc.) for output purposes, the choice for carrying out the integration over a user-defined interval [fmin,fmax] is included.
New in SWAN 40.51 (Mar 23, 2012)
- An alternative of the whitecapping expression based on Alves and Banner (2003) is included. This dissipation term depends on quantities that are local in the frequency spectrum, as opposed to ones that are distributed over the spectrum, as in the Komen formulation (1984). This dissipation formulation can also be combined with the adapted formulation of Yan (1987) for wind growth. This alternative formulation is more accurate for young waves than the default expression of Komen et al. (1984). The combination of the alternative wind input and whitecapping expressions is able to correct both the tendency towards underprediction of wave periods in SWAN and the erroneous overprediction of wind-sea energy under combined swell-sea conditions occuring in nearshore zones. This combination can be obtained with the command GEN3 WESTH (instead of GEN3 KOM).
- Three new output quantities for TABLE and BLOCK: water level, bottom level and smoothed peak period named as WATLEV, BOTLEV and TPS, respectively. Besides the water depth, you can also output the water level and/or bottom level. Whereas RTP (relative peak period) is calculated in an discrete manner (only function of frequency bins), the computation of TPS is made more smoother (i.e. can be a function of any frequency).
- The SWAN documentation is extended and improved. The old User Manual has been split up into two new documents: the actual User Manual and the Technical documentation. Morever, the Programming rules and the manual LaTeX for dummies is added.
- Introduction of the online documentation. The abovementioned documents are also available online.
New in SWAN 40.41 (Mar 23, 2012)
- Effects of diffraction is included. The approximation of these effects is based on the mild-slope formulation for refraction and diffraction but with omission of phase information.
- Introduction of scattered and diffuse reflections.
- An alternative stopping criterion is implemented and is based on the curvature of the iteration curve of the significant wave height. It is found to be more effective in locating the point of model convergence, yielding results that are closer to the fully-converged solution.
- A fast version of the DIA approximation for quadruplets is included. Neighbouring interactions are interpolated in a piecewise constant manner instead of linear one. Moreover, the DIA calculation is carried out in the full spectral circle per iteration (instead of a quadrant per iteration). As a result, a significant speed-up in the computation can be obtained. Use of this technique can be realised by setting QUAD IQUAD = 8. This approach has almost no effect on the model results compared to the default method (IQUAD = 2).
- The Xnl exact method for computing quadruplet interaction, appropriate for finite-depth water, is implemented. This method is, however, extremely time consuming.
- Extra output in PRINT file concerning convergence progress in user-selected geographic points. (Already introduced with patch H of the previous version 40.31.)
- Two new output quantities for TABLE and BLOCK: absolute and relative average wave period Tm-1,0 named as TMM10 and RTMM10, respectively. (Already introduced with patch H of the previous version 40.31.)
New in SWAN 40.31 (Mar 23, 2012)
- For the specification of the discrete frequency space, SWAN permits the user to choose one of the following options:
- The lowest frequency, the highest frequency and the number of frequencies can be specified. This choice is the usual one in the previous versions of SWAN.
- The lowest frequency and the number of frequencies can be specified. The highest frequency will be computed by SWAN such that the ratio of frequency resolution is 10%. This is required by the DIA method.
- The highest frequency and the number of frequencies can be specified. The lowest frequency will be computed by SWAN such that the ratio of frequency resolution is 10%. This is required by the DIA method.
- The lowest and the highest frequencies can be specified. The number of frequencies will be computed by SWAN such that the ratio of frequency resolution is 10%. This is required by the DIA method.
- An exact method called the FD-RIAM, for the computation of the nonlinear 4-wave interactions in finite-depth water, is implemented. This method is extremely time consuming. Hence, it should not be used for production runs.
New in SWAN 40.20 (Mar 23, 2012)
- The SWAN code is parallelized both using MPI and OpenMP.
- Alternative approximations for two physical processes are available:
- M(ultiple) DIA for quadruplets and
- Cumulative Steepness Method for white-capping.
- The Stone's SIP solver is implemented for solving action density equation, in case of non-stationary depth or ambient current. This solver is 4 to 5 times faster than the preconditioned BiCGSTAB solver.
- A frequency-dependent under-relaxation technique is implemented.
New in SWAN 40.11 (Mar 23, 2012)
- SWAN allows nesting in WAVEWATCH III.
- Spherical co-ordinates are available.
- The user can define obstacles at which waves are reflected.
- A higher order propagation scheme is introduced for both the stationary and non-stationary modes.
New in SWAN 40.01 (Mar 23, 2012)
- SWAN permits the calculation of wave-induced set-up. It is exact in 1D cases and approximate in 2D cases.
- Non-stationary boundary conditions are introduced.
- Initial conditions for a stationary or non-stationary computation can now be defined by the user.
- SWAN now also permits a "hotstart", i.e. using a initial condition computed by a previous SWAN run ("hotfile").
- The new version also permits the user to combine stationary and non-stationary computations.
- Source terms can be inspected since they are written to file at (user) selected geographic points.
New in SWAN 30.75 (Mar 23, 2012)
- SWAN can now read and write wind and wave directions using both nautical and Cartesian conventions. The command SET NAUT switches to the nautical convention.
- It is now possible to impose stationary boundary conditions defined by wave spectra that vary along the boundary. The model interpolates between the boundary conditions at given points. The command BOUNDSPEC controls this.
- SWAN now produces a warning if the computed significant wave height differs from the prescribed significant wave height at the up-wave boundary. The command SET [hsrerr] controls the error margin for this warning.
- SWAN can now run in one dimensional stationary mode. The features specific for two dimensional calculations are not available when running in one dimensional mode. The command MODE STAT ONED switches to one dimensional mode.
- When calculating in one dimensional mode, the model can optionally include the effects of wave-induced setup. The command SETUP controls this.