swanmodel-users Mailing List for SWAN

Hello,
I am using SWAN (via Delft3D-WAVE) with 2D spectral boundary conditions from a .sp2 file.
Setup:

  *
Boundary type: SpectrumSpec = from file
  *
The .sp2 file contains multiple locations (~20 points) along the offshore boundary
  *
Each location has a 2D spectrum constructed from ERA5 sea + swell parameters (JONSWAP + directional spreading)

Issue:
When comparing the input spectrum at a boundary point with the model output at the same location, the results do not match (differences in Hs, Tp, and directional distribution).
What I tested:

  *
Verified spectrum construction and scaling to Hs
  *
Checked units (VaDens, m²/Hz/deg)
  *
Verified frequency and direction axes
  *
Tested different file formats
  *
Created a diagnostic case with a single-location (.sp2) boundary file

Observation:
The model response does not clearly reflect the input spectra, especially when multiple boundary locations are used.
Questions:

  1.
How does SWAN use multiple locations in a .sp2 spectral boundary file?
  2.
Are spectra interpolated along the boundary based on location coordinates?
  3.
Can grid/boundary alignment cause SWAN to effectively use only one spectrum?
  4.
Are there requirements for ordering or spacing of locations in the .sp2 file?

Any clarification would be greatly appreciated.
Thank you.



Fatemeh Ameri

ACOS PhD Student

Dear SWAN community,

I am running a 96-hour forecast and I need to save a hotfile after 24 hours
to use it as a hotstart for the next operational run. Following the User's
Manual, I am using these commands:

$*******************COMPUTE 24 HOURS OF FORECAST
PERIOD***************************
COMPUTE NONSTAT 20260328.060000 3600 SEC 20260329.060000
$
$*******************SAVE HOTFILE***************************
HOTFILE 'hotfile_20260329.060000.hot'
$
$*******************COMPUTE THE REST OF FORECAST
PERIOD***************************
COMPUTE NONSTAT 20260329.060000 3600 SEC 20260401.060000
STOP
$

I am comparing the Hs field at 20260329.060000 from two sources:

   1.

   The output from a BLOCK command (cell centers, grid 185×210) at the end
   of this run.
   2.

   The initial state of a new run starting with INITIAL HOTSTART using the
   file generated above (grid nodes, 186×211).

I am noticing differences in the Hs fields (slight offsets in contours and
small magnitude variations). Since I am using the default format for
HOTFILE (ASCII/FREE), could this be a rounding issue? Or is it expected due
to the interpolation between nodes and cell centers?
How would you recommend verifying if the initial conditions are
mathematically consistent with the previous run's end state?

Thank you so much!

Regards,
Natalia

Dear SWAN supports,

I am currently trying to use boundary conditions generated from WAVEWATCH
III (WW3) directly in SWAN using the following command:

BOUNDNEST3 WW3 'ww3_boundary.dat'

My goal is to apply the wave spectrum computed by WW3 as the boundary
condition for a SWAN coastal model.

However, I am not entirely sure about the required format of the boundary
file (ww3_boundary.dat). In particular, I would like to understand what
kind of information needs to be included in the file and how it should be
structured (e.g., header, frequency grid, direction grid, boundary points,
and spectral data format).

If possible, could you please provide an example of a WW3 boundary file
that can be used with the BOUNDNEST3 WW3 option in SWAN? Seeing a sample
file or a reference to the correct format would help me ensure that I
prepare the boundary data correctly.

Thank you very much for your time and assistance.

Best regards,
Sihyeon Lee

Dear all,

I am using SWAN to generate the wave spectra created under extreme typhoon
conditions and I am encountering several issues.

To begin and to consider the worst typhoon condition, what I did is to
provide a spatial wind grid, which corresponds to the worst time of my
typhoon, and to keep this same typhoon conditions for 24h. The ones that
can be seen here:

[image: image.png]

and the, I calculated in the 5 points that can be seen in the image the
wave spectra. However, I expected to get several results in the 5 points,
since their position relative to the eye of the typhoon is the same (same
radius). This is not the case and I am encountering high differences. For
instance, in the top point i get:
Hsig          Tm01          RTpeak        Dir           Depth
[m]           [sec]         [sec]         [degr]        [m]
17.77686       14.5555       15.6174       139.607      200.0000

whereas in the third one, for instance, I get:
Hsig          Tm01          RTpeak        Dir           Depth
[m]           [sec]         [sec]         [degr]        [m]
24.51752       15.0597       17.1698       232.165      200.0000

I am quite confused by these results. I am new in typhoon and waves
modelling and I am not sure if they make any sense. I would expect them to
be similar since the velocity module is similar from one to another. Could
anyone help me?

Also, I am also not sure of which physics I should select. I got these
results using this:
$ -----------------------------
$ PHYSICS
$ -----------------------------
GEN3 KOMEN
WCAPPING KOMEN 2.36E-5 3.02E-3 2.0 1.0 1.0
BREAKING CONSTANT 1.0 0.73
FRIC JONSWAP 0.038

but I also used this for comparison, after reading some papers, and got
very different results:
$ -----------------------------
$ PHYSICS
$ -----------------------------
GEN3 ST6 1.5E-7 2.0E-6 4.0 4.0 UP HWANG VECTAU U10PROXY 32.0 AGROW
SSWELL ARDHUIN 1.2
QUADRUPL
PROP GSE

Now I am not sure which model is more convenient for my case. Could anyone
please help me?

Thank you in advance,

Natalia

Dear all,

I am running SWAN using an unstructured mesh and nautical convention for 
wind and wave direction. Should I use the same convention for the 
current direction? I wondering about it because when I use the same 
convention the current effect seems to be abnormal. When I inverse the 
current direction, the results are more acceptable.

regards,

Hafedh

Dear Swan users,

In my SWAN simulations, the directional spreading parameter (DSPR) seems to
be important for the boundary wave conditions. However, the data available
to me are limited to Hs, TMM10, mean wave direction, wind speed, and wind
direction.

Since DSPR cannot be directly derived from these bulk parameters, I would
like to ask whether it should be estimated using assumed values. If so,
what criteria are typically used in practice (e.g., wind–wave alignment or
wind-sea versus swell conditions), and are there commonly accepted
reference ranges for DSPR?

Any guidance would be appreciated.

Best regards,
Sihyeon

Hi
I believe you are after hot starting the model.

HOTFILE 'restart_abc.xy'

Parallel runs might need concatenation.
 The swan file saves the 2d spectral state, which should be fairly
compatible for next run, unless the wind structure changed significantly.
The following provides the context.
https://www.myroms.org/forum/viewtopic.php?t=4637

--
Nga Mihi
Namaste

KarunaKar Kintada.,


On Thu, 25 Dec 2025, 07:46 Zeinab Salah, <zei...@gm...> wrote:

> Hi,
> Thank you for your reply.
> Please, can you explain clearly how to restart (or make a hot start) for
> SWAN after stopping in the middle of a run? If I run SWAN for a period of
> one year, It will be very difficult to start again from scratch after
> running one or two months.
>
> Best wishes,
> Zeinab
>
>
> ‫في الثلاثاء، 23 ديسمبر 2025 في 2:01 م تمت كتابة ما يلي بواسطة ‪Ali Qorban
> Sarvi‬‏ <‪ali...@al...‬‏>:‬
>
>> hi,
>>
>> simply you could redesign your model from the last time in which the model stopped.but sometimes when the model stops it has a fundamental issue
>> that needs to be addressed ; so previous answers would be wrong, and you need to rebuild the model from scratch again.
>> ------------------------------
>> *From:* Zeinab Salah <zei...@gm...>
>> *Sent:* Monday, December 22, 2025 2:03 PM
>> *To:* swa...@li...; amany Hamdy
>> *Subject:* [swanmodel-users] How to restart swan run
>>
>> Dear All,
>> I want to ask if the SWAN program stops mid-run, how can I start from the
>> last time it stopped?
>> I attached the input file which used to run swan from 20210713.000000
>> to 20210713.230000 every 10 minutes, my questions:
>> 1- how to create a restart file every timestep to be used in case the
>> model stops.
>> 2- Can we run swan for a long time (ex. 10 years )?  In this case if we
>> run it year by year, will we need a restart file?
>> 3- should we modify our input file?
>>
>> Thank you in advance.
>> Best regards,
>> Zeinab
>>
>>
>> _______________________________________________
> swanmodel-users mailing list
> swa...@li...
> https://lists.sourceforge.net/lists/listinfo/swanmodel-users
>

Hi,
Thank you for your reply.
Please, can you explain clearly how to restart (or make a hot start) for
SWAN after stopping in the middle of a run? If I run SWAN for a period of
one year, It will be very difficult to start again from scratch after
running one or two months.

Best wishes,
Zeinab


‫في الثلاثاء، 23 ديسمبر 2025 في 2:01 م تمت كتابة ما يلي بواسطة ‪Ali Qorban
Sarvi‬‏ <‪ali...@al...‬‏>:‬

> hi,
>
> simply you could redesign your model from the last time in which the model stopped.but sometimes when the model stops it has a fundamental issue
> that needs to be addressed ; so previous answers would be wrong, and you need to rebuild the model from scratch again.
> ------------------------------
> *From:* Zeinab Salah <zei...@gm...>
> *Sent:* Monday, December 22, 2025 2:03 PM
> *To:* swa...@li...; amany Hamdy
> *Subject:* [swanmodel-users] How to restart swan run
>
> Dear All,
> I want to ask if the SWAN program stops mid-run, how can I start from the
> last time it stopped?
> I attached the input file which used to run swan from 20210713.000000
> to 20210713.230000 every 10 minutes, my questions:
> 1- how to create a restart file every timestep to be used in case the
> model stops.
> 2- Can we run swan for a long time (ex. 10 years )?  In this case if we
> run it year by year, will we need a restart file?
> 3- should we modify our input file?
>
> Thank you in advance.
> Best regards,
> Zeinab
>
>
>

hi,

simply you could redesign your model from the last time in which the model stopped.but sometimes when the model stops it has a fundamental issue that needs to be addressed ; so previous answers would be wrong, and you need to rebuild the model from scratch again.

________________________________
From: Zeinab Salah <zei...@gm...>
Sent: Monday, December 22, 2025 2:03 PM
To: swa...@li...; amany Hamdy
Subject: [swanmodel-users] How to restart swan run

Dear All,
I want to ask if the SWAN program stops mid-run, how can I start from the last time it stopped?
I attached the input file which used to run swan from 20210713.000000 to 20210713.230000 every 10 minutes, my questions:
1- how to create a restart file every timestep to be used in case the model stops.
2- Can we run swan for a long time (ex. 10 years )?  In this case if we run it year by year, will we need a restart file?
3- should we modify our input file?

Thank you in advance.
Best regards,
Zeinab

Dear All,
I want to ask if the SWAN program stops mid-run, how can I start from the
last time it stopped?
I attached the input file which used to run swan from 20210713.000000
to 20210713.230000 every 10 minutes, my questions:
1- how to create a restart file every timestep to be used in case the model
stops.
2- Can we run swan for a long time (ex. 10 years )?  In this case if we run
it year by year, will we need a restart file?
3- should we modify our input file?

Thank you in advance.
Best regards,
Zeinab

Dear Community,

We are performing a SWAN-SWASH coupling study. In this context, for a better
understanding of the coupling concept, we obtained spectral output from SWAN
model at 1, 10 and 500 points along the open boundary of the SWASH domain.
Then we used these spectra as boundary condition in SWASH model and ran
60-minute simulations for each case.

We are aware that SWASH internally interpolates the input spectra along the
boundary. However, we are uncertain about the appropriate spatial spacing of
the spectral output points.

Our literature review did not yield a clear answer. Therefore, we consider
that it is reasonable to define the spectral inputs at intervals of
approximately one wavelength for swell and wind waves, separately. However,
we are very interested your opinion and suggestions on this subject.        

Best regards,

Semih CAN
Civil/Coastal Engineer, MSc.

Dolfen Consultancy&Engineering

Üsküp Caddesi (Çevre Sokak) 20/3,

Kavaklıdere, 06680 Ankara

T: (312) 468 5930 pbx

F: (312) 468 5941

E:  <mailto:sem...@do...> sem...@do...

W: <http://www.dolfen.com/> www.dolfen.com

 

 

 In case this is helpful, the rompy-swan python package provides a framework to help setting up SWAN, including the generation of the input files like wind, and the full SWAN INPUT cmd file itself. There are a few example notebooks you could check that may be helpful, for example this one. All you need to do is define some base objects like Grid and TimeRange, then you could use them with your wind data (which could be prescribed in different ways, like an xarray object or a netcdf file) to generate your SWAN input files.
Rafael



    On Tuesday, 11 November 2025 at 08:27:05 am NZDT, Sergio Veliz <ser...@gm...> wrote:  
 
 Hello
I left this link to other question with similar answer:
https://sourceforge.net/p/swanmodel/mailman/message/59222557/

Never used grib files, and always have to process a netcdf to a ascii file

Hope it helps!
El lun, 10 nov 2025 a las 15:56, Natalia Rodeiro (<nat...@gm...>) escribió:

Dear SWAN community,
I've been trying to set up the SWAN model for the past few weeks, but I keep running into issues with the wind field input. I downloaded 96 hours of GFS winds, and I'm not quite sure what the correct format is for SWAN to read them.
Since I’m downloading GRIB files, I tried using a Python script to convert them into the format I need. However, even after trying different ways of organizing the data (using u/v components, wind speed and direction, and changing the IDLA options), SWAN still doesn’t read the wind input file properly.

Does anyone have an example of this type of input file? How did you organize the information? Were you also working with GRIBs?
Thank you so much! 
Best regards,Natalia_______________________________________________
swanmodel-users mailing list
swa...@li...
https://lists.sourceforge.net/lists/listinfo/swanmodel-users

_______________________________________________
swanmodel-users mailing list
swa...@li...
https://lists.sourceforge.net/lists/listinfo/swanmodel-users
  

Hello
I left this link to other question with similar answer:
https://sourceforge.net/p/swanmodel/mailman/message/59222557/

Never used grib files, and always have to process a netcdf to a ascii file

Hope it helps!

El lun, 10 nov 2025 a las 15:56, Natalia Rodeiro (<nat...@gm...>)
escribió:

> Dear SWAN community,
>
> I've been trying to set up the SWAN model for the past few weeks, but I
> keep running into issues with the wind field input. I downloaded 96 hours
> of GFS winds, and I'm not quite sure what the correct format is for SWAN to
> read them.
>
> Since I’m downloading GRIB files, I tried using a Python script to convert
> them into the format I need. However, even after trying different ways of
> organizing the data (using u/v components, wind speed and direction, and
> changing the IDLA options), SWAN still doesn’t read the wind input file
> properly.
>
> Does anyone have an example of this type of input file? How did you
> organize the information? Were you also working with GRIBs?
> Thank you so much!
>
> Best regards,
> Natalia
> _______________________________________________
> swanmodel-users mailing list
> swa...@li...
> https://lists.sourceforge.net/lists/listinfo/swanmodel-users
>

Dear SWAN community,

I've been trying to set up the SWAN model for the past few weeks, but I
keep running into issues with the wind field input. I downloaded 96 hours
of GFS winds, and I'm not quite sure what the correct format is for SWAN to
read them.

Since I’m downloading GRIB files, I tried using a Python script to convert
them into the format I need. However, even after trying different ways of
organizing the data (using u/v components, wind speed and direction, and
changing the IDLA options), SWAN still doesn’t read the wind input file
properly.

Does anyone have an example of this type of input file? How did you
organize the information? Were you also working with GRIBs?
Thank you so much!

Best regards,
Natalia

Dear Sihyeon Lee

If you define the boundary conditions at two or more points along a
boundary line, SWAN will handle the interpolation itself.
See the manual information for the BOUNDSPEC command with the VARIABLE option.

Best regards

Paulo Avilez-Valente


Dr-Eng Paulo Avilez-Valente
Assistant Professor
Faculdade de Engenharia
Universidade do Porto
Rua Dr Roberto Frias
P-4200-465 Porto
Portugal

On Thu, 6 Nov 2025 at 20:17, 이시현학부생 via swanmodel-users
<swa...@li...> wrote:
>
> Dear SWAN supports,
>
> Hi there, I am currently conducting numerical wave modeling using the SWAN model.
> At present, I have observed wave data (such as significant wave height, period, and direction) from a single point. For one latitude line, there are only two or three observation points available.
>
> So far, I have applied the data from a single observation point uniformly along one boundary side (SIDE) to run SWAN. However, I have found some limitations with this approach.
>
> To improve the boundary condition, I am now trying to construct the boundary using multiple observation points — specifically, by interpolating between two points to generate wave conditions along the segments between them.
>
> My question is:
>
> What interpolation methods are generally recommended for such boundary construction (e.g., linear, spline, or others)?
>
> Or, are there alternative approaches to represent spatially varying wave conditions along the boundary instead of simple interpolation?
>
> Any guidance or references you could share would be greatly appreciated.
>
> Thank you very much for your time and help.
>
> Best regards,
> Sihyeon Lee
>
> _______________________________________________
> swanmodel-users mailing list
> swa...@li...
> https://lists.sourceforge.net/lists/listinfo/swanmodel-users

Dear SWAN supports,

Hi there, I am currently conducting numerical wave modeling using the SWAN
model.
At present, I have observed wave data (such as significant wave height,
period, and direction) from a single point. For one latitude line, there
are only two or three observation points available.

So far, I have applied the data from a single observation point uniformly
along one boundary side (SIDE) to run SWAN. However, I have found some
limitations with this approach.

To improve the boundary condition, I am now trying to construct the
boundary using multiple observation points — specifically, by interpolating
between two points to generate wave conditions along the segments between
them.

My question is:

   -

   What interpolation methods are generally recommended for such boundary
   construction (e.g., linear, spline, or others)?
   -

   Or, are there alternative approaches to represent spatially varying wave
   conditions along the boundary instead of simple interpolation?

Any guidance or references you could share would be greatly appreciated.

Thank you very much for your time and help.

Best regards,
Sihyeon Lee

Dear SWAN group,

I'm using SWAN v41.51 with an unstructured triangular mesh generated for
ADCIRC (fort.14 file), and I need to define boundary conditions between
certain nodes.

I've tried different methods, for example, specifying the nodes:
BOUndspec SEGMent IJ 650 125 1 57 170 225 1161

I also tried using xy coordinates (BOUndspec SEGMent XY), but I get the
following error:
'Terminating error: SwanBpntlist: list of boundary vertices could not be
completed'

I've attached the model files, along with the fort.14 mesh, to this Google
Drive link:

https://drive.google.com/drive/folders/1m26MyRWZ8fEMOa5Ej_VP74WF0CiJ5BMJ?usp=drive_link

Any guidance would be greatly appreciated.


-- 

Cristián Santander Escudero.
Ingeniero Civil Oceánico.
Universidad de Valparaíso.
LinkedIn <https://www.linkedin.com/in/cristi%C3%A1n-santander-70262921/>

Dear SWAN community,

We recently replicated a wave modeling case in Antarctic polynyas using
SWAN. The full scenario runs in about 4.25 hours on average using the
Inductiva API.

We’ve documented the setup and results here:
🔗 https://inductiva.ai/guides/swan/modeling-waves-in-polynyas/index

Feedback is very welcome. If there are other cases or published studies you
think would be worth exploring, feel free to share them.

Best regards,
-- 
*Eunice Oliveira*
Product Owner at Inductiva.AI

Dear SWAN support team,

I am currently setting up a SWAN model using a *curvilinear grid*. My input
lines are:

CGRID CURVILINEAR 3 1 EXC -999 -999 CIRCLE 36 0.05 1.0 30READGRID COOR
1. '/Volumes/Krong/Pohang/Depth_data/Pohang_CoordBlocks.txt' 1 0 0
FREE

However, SWAN does not seem to read my coordinate file correctly.
I would like to ask for clarification about the exact format required for
the coordinate file when using READGRID COOR.

   -

   Should the file contain two blocks (first the X-coordinates, then the
   Y-coordinates) in matrix form?
   -

   For example, for a grid defined as CGRID CURVILINEAR 3 2 ..., should the
   file look like this?

129.45 129.46 129.47
129.45 129.46 129.47

36.00  36.00  36.00
36.01  36.01  36.01

I would greatly appreciate it if you could confirm the correct formatting,
or provide a small working example file for reference.

Thank you very much for your time and support.

Best regards,
Sihyeon

Hi Zhiyun,
Good day.
The time series input is a great approach, but essentially the model
indicates the energy needs redistribution in some sorts.

Wondering if the depth is too shallow for assumed spectral construct, i.e.,
the model isn't as simple as TPAR, might need better parameterisation or
change the model domain.

Regards

--
Nga Mihi
Namaste

KarunaKar Kintada.,


On Thu, 25 Sept 2025, 06:13 Zhiyun Du via swanmodel-users, <
swa...@li...> wrote:

> Dear SWAN group,
>
> I am running a SWAN model and having boundary convergence issues. The open
> boundary condition to force swan was downloaded from the WW3 model outputs.
> I used TPAR files for boundary inputs.
>
> I started my model from 2005, and when it ran until some times, some of
> the TPAR files showed this error:
>
> Boundary data type TPAR processed, time: 83289600.
> Boundary data type TPAR processed, time: 83300400.
> Boundary data type TPAR processed, time: 83311200.
> Boundary data type TPAR processed, time: 83322000.
> ** Severe error : No convergence calculating the spectrum
> ** Severe error : at the boundary using parametric bound. cond.
>
> Then, I changed my start time to 2008 just to let the model check the
> boundaries. I found many "severe no convergence error" in different files
> and at different times.
>
> The only way I can let the model run is to comment out the TPAR files that
> had this error. However, I will lose wave inputs at these TPAR
> locations(?). I tried to modify the values at these "bad times" by (1)
> simply deleting or (2) interpolating from near hours, but none worked, and
> the error still existed.
>
> I am writing to ask if you may have this issue before and know how to fix
> it. Thank you very much.
>
> Best,
> Zhiyun
>
>
>
> Zhiyun Du
> Andrews Hall 215 | PhD student
> Department of Physical Sciences
> Virginia Institute of Marine Science
> _______________________________________________
> swanmodel-users mailing list
> swa...@li...
> https://lists.sourceforge.net/lists/listinfo/swanmodel-users
>

I am out of the office this week so please allow additional time for responses. 

 
If you are at the Workshop on Waves, Storm Surge and Coastal Hazards in Santander, ES, you can find me there as well.

 
For urgent matters please email er...@oc... or oc...@oc....

 
 
Thanks for your understanding!

 

Dear SWAN group,

I am running a SWAN model and having boundary convergence issues. The open boundary condition to force swan was downloaded from the WW3 model outputs. I used TPAR files for boundary inputs.

I started my model from 2005, and when it ran until some times, some of the TPAR files showed this error:
Boundary data type TPAR processed, time: 83289600.
Boundary data type TPAR processed, time: 83300400.
Boundary data type TPAR processed, time: 83311200.
Boundary data type TPAR processed, time: 83322000.
** Severe error : No convergence calculating the spectrum
** Severe error : at the boundary using parametric bound. cond.

Then, I changed my start time to 2008 just to let the model check the boundaries. I found many "severe no convergence error" in different files and at different times.

The only way I can let the model run is to comment out the TPAR files that had this error. However, I will lose wave inputs at these TPAR locations(?). I tried to modify the values at these "bad times" by (1) simply deleting or (2) interpolating from near hours, but none worked, and the error still existed.

I am writing to ask if you may have this issue before and know how to fix it. Thank you very much.

Best,
Zhiyun



Zhiyun Du
Andrews Hall 215 | PhD student
Department of Physical Sciences
Virginia Institute of Marine Science
[cid:55e85f39-e879-4ab2-b5e8-779ffb595fef]

Hi Sihyeon,
It's bit tricky to understand the problem with out knowledge of area being
simulated. But two things to consider.
1. Is there any wind generation component.
2. Is the water shallow for spectral changes within few cells?
Definitely not wave breaking, as wave heights are increasing, not strong
reflection unless specified and not sure triads are. Is friction enough?

--
Nga Mihi
Namaste

KarunaKar Kintada.,


On Thu, 18 Sept 2025, 23:52 이시현학부생 via swanmodel-users, <
swa...@li...> wrote:

> Dear SWAN Support Team,
>
> I am currently conducting wave modeling using SWAN for a coastal region,
> and I have encountered an issue at the model boundary.
>
> At the beginning of the simulation, the significant wave height (Hs) at
> the open boundary matches the prescribed input condition. However, as time
> progresses, I observe that the wave height on the right-hand side of the
> boundary becomes larger than the intended input, in some cases by up to 0.6
> m.
>
> From my understanding, this may be related to wave energy not leaving the
> domain properly and being accumulated near the boundary. I have learned
> that some other wave models (e.g., Boussinesq-type models, CFD solvers)
> implement a "sponge layer" to absorb excess energy, but it seems that SWAN
> does not provide such a direct option.
>
>
> Could you kindly advise how to properly handle this boundary condition in
> SWAN, so that the incoming wave at the open boundary remains constant
> throughout the simulation?
> For example, is there a recommended practice (such as domain extension,
> nesting, or applying certain dissipation mechanisms) to avoid this kind of
> boundary growth?
>
> Your guidance would be greatly appreciated. Thank you very much for your
> support.
>
> Best regards,
> Sihyeon
> _______________________________________________
> swanmodel-users mailing list
> swa...@li...
> https://lists.sourceforge.net/lists/listinfo/swanmodel-users
>

Dear SWAN Support Team,

I am currently conducting wave modeling using SWAN for a coastal region,
and I have encountered an issue at the model boundary.

At the beginning of the simulation, the significant wave height (Hs) at the
open boundary matches the prescribed input condition. However, as time
progresses, I observe that the wave height on the right-hand side of the
boundary becomes larger than the intended input, in some cases by up to 0.6
m.

>From my understanding, this may be related to wave energy not leaving the
domain properly and being accumulated near the boundary. I have learned
that some other wave models (e.g., Boussinesq-type models, CFD solvers)
implement a "sponge layer" to absorb excess energy, but it seems that SWAN
does not provide such a direct option.


Could you kindly advise how to properly handle this boundary condition in
SWAN, so that the incoming wave at the open boundary remains constant
throughout the simulation?
For example, is there a recommended practice (such as domain extension,
nesting, or applying certain dissipation mechanisms) to avoid this kind of
boundary growth?

Your guidance would be greatly appreciated. Thank you very much for your
support.

Best regards,
Sihyeon

Dear SWAN community,

We are pleased to share that we have integrated *UnSWAN*, the
unstructured-mesh version of the SWAN model, into our platform.

To help validate the implementation and move toward making it available for
broader community use, we are currently looking for a *public use case*
suitable for testing.

If you know of any open or well-documented test cases or if you are
interested in collaborating on this effort, we would greatly appreciate
your input.

Best regards,

Eunice Oliveira
Inductiva.AI
eol...@in...