Coastal / Estuary

HYCOM data for gridded wind and pressure fields

2021-09-01T14:12:49Z

I am having trouble converting HYCOM data into a FM-readable format (gridded wind fields).

gridded p-field: "airprs" in file "cfsv2-sec_2018_01hr_sfcprs.nc" has a scale_factor = 0.00390625f and offset = -29.236965f and add 100,000 to convert to Pa.

gridded x-field: "wndewd" in file "cfsv2-sec2_2018_01hr_uv-10m.nc" has scale_factor = 0.0026041667f

gridded y-field: "wndnwd" in file "cfsv2-sec2_2018_01hr_uv-10m.nc" has scale_factor = 0.001953125f

Has anyone written a code that converts these fields into an .amu, .amp, .amv format that Delft3D-FM can read?

RE: Model Output as Boundary Condition for Nested Model

2021-07-13T08:23:01Z

Hi Kevin,
You can try to use Nesting toolbox in Delft DashBoard. I believe it supports D-Flow FM models.
Regards,
Dmitry

RE: Model Output as Boundary Condition for Nested Model

2021-07-02T20:01:50Z

To add, I see that there is a NESTHD tool for Delft3D-FLOW but do not see this tool for the Flexible Mesh Suite. Thank you.

Model Output as Boundary Condition for Nested Model

2021-07-02T19:31:28Z

Hi there, I am relatively new to Delft and am using the Flexible Mesh Suite to develop a hydrodynamic and sediment transport model for a coastal system within a large bay area. My study site is a short piece of shoreline within the larger coastline and I am performing runs over long time periods, which becomes computationally challenging when incorporating the entire bay as part of my domain. Even when creating nested domains of finer scale within a coarser domain, the computational time is extreme. I am wondering if there is a way to easily use the output from a coarser, larger domain model run as the input for boundary conditions of a smaller, finer domain that is focused around my project site. I imagine this would be similar to an offline coupling of the Flow and Wave model, but I am looking to essentially couple two Flow models.

Any help would be much appreciated.

Thank you!

Integrated Wave and Flow model Setup issues

2021-06-23T22:05:26Z

Hello,

I am developing an integrated wave and flow model to compute combined shear stresses in a system. The flow model will compute shear stresses in standalone mode, but when linked to the wave model, shear stresses result in zeros. Wave conditions are also not output in the flow model his or map results but are included in the wave outputs. The com file has both wave and flow data but the wave model does not always converge on a solution resulting in intermittent wave results in the com files.

Below are a few questions that may help me troubleshoot the issue

Can the wave model grid be smaller than the flow grid? The Wave and flow grid do not cover the same extents. With the wave model being smaller.
What happens to the communication and computation steps if the wave model does not converge on a solution?
Do the Hurdle-Stive or Young-Verhagen wave models work with complex structures in the flow model?
In Delft3D-Flow, two shear stress variables were generated. TauMax, and Taucurrent. In Dflow-Fm, only one shear stress result is output. In Dflow-FM, does the taucurrent represent flow+wave induced shear stress or is there another variable that includes that?
Is there a document that outlines best practices to develop a successful integrated model?

One other issue is the inability to assign wave boundaries using the gui interface. The wave boundary tool will snap to some grid extents but not others. Is there a workaround or something to look out for that would be causing this issue?

Thank you for any help or guidance you could provide.
-Sam

RE: Error using Flow+Wave+Sediment with multiple layers

2021-06-21T15:42:18Z

Dear Marina,

Conjugate gradient SAAD errors are very difficult to solve without further information, since it can result from many causes/issues/bugs. When you're using an official Delft3D-FM release under your affiliation's support contract, please direct your questions directly to: delft3d.support@deltares.nl. When you don't have a support contract, you can ask delft3d.support@deltares.nl, what the possibilities are for helping you in resolving the conjugated (gradient) SAAD errors.

Best regards,
Tjitske

RE: Error while initializing space-varying wind

2021-06-17T07:23:56Z

I have the same problem (version: 1.2.110.68456M)

Storm surge modelling - extremely high wind drag coefficients?

2021-05-21T06:31:59Z

Dear all,
I run a model of the Venetian lagoon, which has been calibrated against for the tide based on a extended period without the influence of wind (see tidalcalibration.png). Performance is really good. However, I want to actually run the model for very stormy conditions. When taking into account a uniform wind- and pressure field over the model domain which had been done in other studies as well the default linearly varying drag coefficient (cf. Smith and Banke (1975)) underestimate the peak by about 20 cms (see StormEvent_windDrag_adjustment.png). I have to change the wind drag coefficient for 100 m/s from 0.00723 to 0.0123 in order to be able to reproduce the peak.

However, when running a validation calculation for another storm event (see tidal_signal_PuntaSallute.png) the chosen wind drag coefficients seem to overestimate the peaks.

I am now trying to find possible reasons why I need so extremely high wind drag coefficients in the first place. Does anybody know possible reasons for this?
I checked my boundary forcing (identical with the ones used in other studies), bathymetry (make sure to use correct reference datum), and bottom friction. I define the wind input by means of a uniform wind speed and direction .tim file. Same for the pressure.

Looking forward to your thoughts on this,
Thank you and all the best,
Julius

Error using Flow+Wave+Sediment with multiple layers

2021-05-14T12:42:28Z

Hey guys, I'm actually using version 2021.03 for my master thesis, I do have a problem and I don't know how to solve it. I coupled Flow and Wave and added Sediment for modeling the profile of a coastline. If I'm running the simulation with only one layer everything works. If I'm running the simulation with multiple sigma layer and only Flow+wave everything works. If I use multiple layers and flow+wave+sedi I do get the error "Remote process not available / terminated during call Update" immediately. I don't know what to do.. In the flow output dia there is the error "ERROR : conjugategradientSAAD: error" show. Does anyone know how to solve that problem?

Thanks for help!

Error while initializing space-varying wind (solved)

2021-10-04T05:51:05Z

Hello,
The diagnosis file shows the error below when I use the time- and space-varying wind on an equidistant grid format,
even with the same computational grid that worked well with different external forcing input such as spider-web.
----------------------------------------------------------------------------------------------------------------------------------
** WARNING: ERROR: Looking for ncols (arc-info), but getting: FileVersion = 1.03
** ERROR : flow_initexternalforcings: Error while initializing quantity: windx Check preceding log lines for details.
----------------------------------------------------------------------------------------------------------------------------------
(but log file shows nothing)

Have you experienced such errors?
I would appreciate it if you can share any ideas or check if the attached files have anything wrong.

=================================================================================================
I've found how to deal with this.
This can be solved by inserting three comments lines before the input information of each file (.amu, .amv, and .amp),
because it is sensitive to the number of lines of the header to be initialized.
For example:
### Start of Header
### This file is created by ...
### Additional comments
FileVersion = 1.03
...
unit1 = m s-1
### End of Header
TIME = 0 minutes since 0000-00-00 00:00:00 +00:00
...

Jets/problems on open boundary of 3D sigma model

2021-03-16T18:15:16Z

Hi All,
We are setting up a 3D sigma model with salt to look at circulation in the northern Gulf of Mexico, USA. The hydrodynamics appear smooth and reasonable for the 2D and 3D model, until meteorological forcing is included. Once the winds/pressure are applied, velocities on the open boundary become elevated and generate jets without ultimately blowing up the run. We have tried most of the numerical filters and other options without success. Has anyone seen this problem before or have experience stabilizing this type of model?

See the depth-averaged currents, top layer salinity, and a summary of the model:
https://rdedrivepub.erdc.dren.mil/url/mec3nkjiqgawtxeb pw: 84q2ddjd
https://rdedrivepub.erdc.dren.mil/url/rzd5yifztzpr2pbp pw: uz9r4a5b
https://rdedrivepub.erdc.dren.mil/url/quh2iucvvhpcgcj2 pw: tjnc3yrp

model set up:

10 sigma layers
cold start with 35 ppt initial salt distribution
constant, uniform 35 ppt salt condition on offshore open boundary
tidal water level on open boundary
15+ fresh water inputs on coast line
spatially, temporally varying winds/pressures from NOAA North American Regional Reanalysis products
36 MPI subdomains

Thanks
Cody JohnsonUS Army Corps of EngineersCoastal and Hydraulics Laboratory (CHL) Engineer Research and Development Center(601) 634-2552 (office)(239) 233-0155 (cell)Cody.L.Johnson@erdc.dren.milCody.L.Johnson@usace.army.mil

tidal boundaries

2021-02-17T08:02:27Z

I have a problem each time i try to make the open boundaries water level it gives me an empty file bca or sometimes even refuse to generate it, so can anybody help me in that

RE: positive and negative values below reference plane

2020-11-18T08:21:17Z

Hi Marina,
I don't know the exact reason for this. My guess is that D-Waves can handle only structured grids (recti- or curvilinear), which where initially used by Delft3D-FLOW and Delt3D-WAVE (structured). This implies that one have to prepare separate set of files for D-Waves (including grids), to perform coupled simulation. Check out example 12_dflowfm, which contains test case "e100_f02_c02-FriesianInlet_schematic_FM_wave" for the coupled FM + Wave simulation. To answer your question about converting bed level from FM to Wave notation: the simplest way to do that is to export D-Flow FM bathymetry to .xyz-file, load it into Waves model and then multiply samples by -1 using "Set value" - "Multiply" in Delta Shell spatial editor tab (screen-grad attached).

Regards, Dmitry

RE: positive and negative values below reference plane

2020-11-17T15:05:21Z

Thanks Dmitry,do you know the reason for that?And if I want to couple them and I say I want to use the Bed level from Flow, is the program converting the values by itself, or can't I use the values automatically and I need a separate bathymetry?

RE: positive and negative values below reference plane

2020-11-17T12:54:08Z

Hi Marina, That's right. In D-Flow FM (unstructured grids), the sign convention for bathymetry is positive upwards. In D-Waves (curvilinear grids) depth is positive downward.
Regards, Dmytro

RE: positive and negative values below reference plane

2020-11-13T09:42:24Z

Hei Sebastian, thanks for your response, but in the manual is written:
Flow: 5.4.4 Bed level
When you double click on Bed level in the Project window or select Bed level from the dropdown box in the spatial editor section of the Map ribbon, the spatial editor is activated (Figure 5.34). This editor can be used to generate a bathymetry for your computational grid. How to work with the spatial editor is described in Appendix H. Be aware that the bathymetry in D-Flow FM is de?ned as the bed level (e.g. positive upward), implying that all bed levels below the reference plane are negative. By default the bed levels are de?ned on the net nodes.

Wave: page 35:
During the computations, D-Waves determines the water depth from the bottom level, the water level and the water level correction. Bottom levels are de?ned as the level of the bottom relative to some horizontal datum level (e.g. a still water level), positive downward. Water levels are de?ned with respect to the same datum as the bottom; the water level is positive upward.

If I get it right, two different directions (negative or positive) of the axis are explained?

Storm Surge Model showing abrupt result! How to set Initial Conds and BC?

2020-11-10T17:02:40Z

Hi,
I am trying to set up a coastal flooding model using Delft3D FM for Hurricane Florence, NC, USA. However, the model without wind and pressure fields shows tidal water level liitle bit reasonable but with wind- and pressure-field of Florence, it shows wiered results. Could anyone give me some expert comments on that how I can improve the model.
here is my Water Level with, and without hurricane, the lower one is for the hurricane, where water level has drastically depressed instead of increasing!
I have also added the pressure field of Hurricane from HWRF.
Note: I will also upload the model credentials if anyone is interested to look into it!

RE: positive and negative values below reference plane

2020-11-10T13:26:52Z

Hi Marina!In Delft3D-FM all levels are measured with a positive vertical axis "pointing up", i.e. oposed to the vector "g" (gravity).
Hope it helps.Sebastian

positive and negative values below reference plane

2020-11-10T10:54:44Z

Hi everyone,I'm using Delft3d-FM for a university project and during studying the Manuels for Flow and Wave I recognized a discrepancy. Flow is measuring the bed below the reference plane as negative, so e.g. land above the water surface -> positive, bed level in the middle of the lake ->negative.
In the Wave manual is written that the bed level is measured downwards positive.Is that only valid if I do both programs standalone? If I want to couple them and I say I want to use the Bed level from Flow, is the program converting the values by itself, or can't I use the values automatically and I need a separate bathymetry?I hope you understand my struggle and that someone can help me or share their experiences?
Thanks and kind regards,
Marina

D-Flow FM model crashes with evaporation and precipitation on

2020-04-16T15:20:33Z

Hi all,
I'm investigating physical processes (temperature and salinity ) in a coastal lagoon, using 10 sigma-layers in vertical direction.
When I try to add a cross-section to the model, it crashes with no warning message.
When switching temperature and salinity off, the model seems to be run smoothly with cross-sections.
Nb: The screen shots messages inform that the Deltares integrated model runner stopped working and that it doesn't work (it happens all the time I try to start a model with cross-sections).

Update. The crash was caused by a line in the *.mdu-file "Wrimap_evaporation = 1", not by a cross-section addition. When this parameter is set to 0, the model runs fine. The behaviour is observed even in the last tagged version of the D-Flow FM source code (66357).

Kind regards,
Dmitry