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how to model a brine discharge in the sea

Hello, I would like to know how to perform a near and far field modeling with OpenFlow Flood of the brine discharge (coming from a desalination plant) in the sea.

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  • Hello Jorge,

    A brine discharge can be simulated by OpenFlows FLOOD. To do it you'll need to setup a 3D hydrodynamic simulation by creating a new domain using MOHID Water numerical engine (see more information here). Then create a new simulation

    Being a 3D simulation, the setup of the model will greatly depend on the area you're trying to simulate and the processes governing hydrodynamic circulation in that area. For simulation brine discharges, where buoyancy plays a decisive role, your model should be setup to simulate tide and 3D wind and density driven currents. This is required as the initial dilution and shape of brine plume will depend directly from it. 

    So you'll require realistic initial and boundary conditions for water level, currents, temperature and salinity. For water elevations at the open boundary you can use a global tide solution as described here. For the currents, temperature and salinity it depends on the area you're simulating, but using a global/regional circulation solution (EU Marine Copernicus, NOAA; etc) is rtypically recommended. The use of nested models methodology may be required when doing this type of applications. For 3D applications the use of an appropriate treatment of vertical turbulence is of extreme importance, so you'll need to activate module GOTM your simulation. Also the vertical resolution of your model must be adequate to be able to represent the vertical density gradients especially near the bottom, as the brine plume will be transported near the bottom. 

    As this is a complex simulation (not related with tide) FLOOD user interface for configuring each module does not contain all the necessary options, so you'll need to use the text editor to setup each module. To do this follow the instructions here

    Once you have your 3D hydrodynamic simulation implemented and validated, you can then setup the brine discharge. There are several ways of doing it depending on the characteristics of the discharge. Is the brine discharge made via a submarine outfall or a surface discharge? If it's a submarine outfall you will want to activate module Lagrangian which simulates using particle tracking methods the dispersion of the plume (in the near field and far field). In the Lagrangian module input file. you can specify specific commands to compute the near field namely COMPUTE_PLUME   : 1 and the path to the submarine outfall configuration file (JET_DATA_FILE         : ..\General Data\Outfall\Outfall.dat) where you define parameters such as outfall length, position and orientation, number of ports and orientation, etc. You'll need to specify the characteristics of the discharge (flow, temperature and salinity). Then run the simulation and check the outputs from the near field model (dilution, shape and position of the equilibrium point of the plume in the far field, etc). You can then use the Eulerian transport module (Water Properties and DIscharges module) to configure your discharge in the far field. This is required as it is a negatively buoyant plume 

    I understand this is a very generic answer to your question. If you provide more details regarding the type of application you're trying to do I'll be glad to help. 

    Kind regards,
    Luis

  • I was reviewing some youtube videos and to create the domain, several photos must be uploaded to the Digital Terrain Model section, these photos correspond to the place where I want to model? should I upload many photos of the same place? Beforehand thank you very much

  • Hello Jorge,

    Could you clarify what you mean about photos? 

    To create a digital terrain model, for your specific case which is a coastal application, you'll need bathymetry data (xyz, raster, shapefile, etc). 

    You can find detailed information about constructing a digital terrain model here

    Kind regards,

    Luis

  • Hi Luis! , Thank you very much for your answers, you have been very helpful.
    I had a doubt regarding OpenFlows Flood, the software can simulate both the near field and the far field? If yes, should I calibrate and validate each field separately?. Where could I find information on input parameters to calibrate and how to do it? In advance, thank you very much!

  • Hi Jorge,

    Yes, OpenFlows FLOOD can simulate the near field and far field, but for brine discharges you'll probably need to use a different approach. As I mentioned before the methodology depends on the characteristics of the discharge, specially if the outflow is very high.

    One of the most common ways to simulate a brine discharge (with negative buoyancy), would be to simulate the near field (using Lagrangian/Jet modules) to calculate the initial dilution and shape/position of the plume and output the results. Then run a 3D high resolution simulation (with thin vertical layers near the bottom) using that information and determine the far field using an Eulerian approach.

    Regarding the input parameters, you would need to setup the Jet options (near-field) inside the Lagrangian module setup. Keep in mind that you first need to setup a high resolution model in near the submarine outfall to get the 3D velocity and density fields, as I've mentioned in an earlier answer. Then setup a simulation with the Lagrangian module. when you do this a sample Lagrangian file is added to your simulation, where you can specify the discharge parameters (e.g. position, type of emission, flow, etc). Below an example

    <BeginOrigin>

    ORIGIN_NAME                :  Brine discharge 

    EMISSION_SPATIAL        :  Point

    EMISSION_TEMPORAL  : Continuous

    MOVEMENT                     : SullivanAllen

    VARVELHX                       : 0.2

    VARVELH                         :  0.05

    TURB_V                           : Constant

    VARVELVX                       : 0.02

    VARVELV                         : 0.005 

    DT_EMIT                           : 60 !emission frequency, e.g. every 60 seconds

    NBR_PARTIC                    : 10 !number of particles emitted in each emission

    FLOW                                : 0.5  !flow in m3/s

    ...

    <EndOrigin>

     

    Still inside the block <BeginOrigin>/<EndOrigin>.you'll need to define the submarine outfall parameters by adding the following keywords that respectively 

    COMPUTE_PLUME           : 1   !run near field model (0/1)

    JET_DATA_FILE               : ..\General Data\Outfall\Outfall.dat   !path to the outfall characteristics

    JET_DT                             : 600.   !run near field model every 600 seconds

    Then inside the file defined by the JET_DATA_FILE keyword, add the following keywords: 

    PORT_DIAMETER             : 0.1  -> Diameter of each port (m)

    PORT_BOTTOM_DISTANCE      : 0.5      -> Port distance from the bottom (m)

    PORT_ANGLE_XY             : 90  -> Port horizontal angle (º)*

    PORT_ANGLE_HZ             : 0  -> Port vertical angle (º)**

    OUTFALL_LENGTH            : 100       -> Outfall length (m)

    OUTFALL_ANGLE             : 180       -> Outfall angle (º)*

    PORTS_NUMBER             : 50    -> Number of ports

    *Angle with XX axis (0º = East, 90º = North)

    ** Angle with bottom (0º = parallel to bottom, 90º = perpendicular to bottom)

    Don't forget that in the Lagrangian origin you must also define the salinity and temperature of the discharge by adding the following blocks inside the  <BeginOrigin>/<EndOrigin> block:

    <<BeginProperty>>

    NAME                          : temperature

    UNITS                          : degC

    CONCENTRATION      : 21

    <<EndProperty>>

    <<BeginProperty>>

    NAME                        : salinity

    UNITS                       : psu

    CONCENTRATION    : 72

    <<EndProperty>>

     Then run the simulation and a results file will be written in the "res" folder of your domain. The name of the file is the name of the origin with an extension ".jet". The output file contains the initial dilution, and position of the plume and concentration in the equilibrium with ambient water. You can then use this information to set an eulerian discharge and run a simulation for the far field and analyze the plume dispersion. 

    I know this is a rather extensive answer and still probably very incomplete, but it contains most of the information necessary to start. Please let me know if you have any additional questions. 

    Kind regards,
    Luis

  • Hello Luis, thank you for your previous answer.
    I had a doubt, by following the instructions of "Global tidal solutions for coastal hydrodynamics" (Loading the FES2014 file) And in order to do that, my computational grid must be at geographic coordinates WGS84 or UTM. So far in the only section where something about geographical coordinates comes out is in the section "Raster Layer collection", Laster Properties, projections, In the type I have marked "Projections" or "Geographic", and i have searched in the option Major for some coordinate WGS84 or UTM option, I only find the option in Major "TransverseMercator" and Minor is automatically marked with a coordinate. Anyway, when I want to upload the FES2014 file for "Global Tidal Solutions for Coastal Hydrodynamics" I keep getting the same message that the coordinates must be in WGS84.

    I hope you can help me,

    thank you very much

Reply
  • Hello Luis, thank you for your previous answer.
    I had a doubt, by following the instructions of "Global tidal solutions for coastal hydrodynamics" (Loading the FES2014 file) And in order to do that, my computational grid must be at geographic coordinates WGS84 or UTM. So far in the only section where something about geographical coordinates comes out is in the section "Raster Layer collection", Laster Properties, projections, In the type I have marked "Projections" or "Geographic", and i have searched in the option Major for some coordinate WGS84 or UTM option, I only find the option in Major "TransverseMercator" and Minor is automatically marked with a coordinate. Anyway, when I want to upload the FES2014 file for "Global Tidal Solutions for Coastal Hydrodynamics" I keep getting the same message that the coordinates must be in WGS84.

    I hope you can help me,

    thank you very much

Children
  • Hello Jorge,

    I believe you may be confused with the workflow to create a computational grid and digital terrain model.

    Please read this article regarding coordinate systems and projections in OpenFlows FLOOD. Then to create a computational in WGS84 geographical coordinates please read this article. After creating the grid you can create the digital terrain model (bathymetry). You can find information here

    Additionally this video may also help to have a clearer idea of the workflow. Keep in mind that you can load different sources of data to construct your digital terrain model (xyz, raster, etc) in different coordinate systems. 

    Please let me know if you require any additional information. 

    Kind regards,
    Luis

  • Hello Luis ! , I appreciate your previous answers. I wanted to consult on global/ regional circulation solution that you mentioned for currents, temperature and salinity. Where could I find information on what global/regional circulation solution means, is some kind of information archive with the currents, temperature and salinity of different parts of the world? as is FES2014?. In advance, thank you very much!

  • Hi Jorge,

    You can find that in EU Marine Copernicus Service.

    If you register and download data from there, then there are some OpenFlows FLOOD support tools (ConvertToHDF5) that can convert this data into HDF5 format that OpenFlows FLOOD can read. 

    Kind regards,
    Luis

  • Hello Luis! ,

    I would like to ask about the necessary models that I should choose for the simulation of the near and far field. I have carefully read every answer given to me,

    So for the near field model I intended to use the modules:
    Lagrangian (jet model); Hydrodinamyc; Model, Geometry, Turbulence model (GOTM).

    While for the far field I intended to use the modules:
    Hydrodynamic, Model; Geometry, Eulerian (Waterproperties, discharge model), interfacesedimentwater.

    I’d like to know what you think about those models. In my case, generally I want to simulate the discharge of brine into the sea by submarine emissary with different number of diffusers (I want to do several simulations to find the optimal number of diffusers to ensure faster dilution), also that both spatially extend the brine plume and in which concentrations, calculate the initial dilution of the mixing zone, the point at which the concentration of the feather is equal to that of the middle and also that both the feather can be extended spatially and at how many meters the equilibrium of concentrations is reached and how long it takes.

    In advance, thank you very much!

  • Hello Jorge,

    In fact you always need all these modules for running a simulation (using MOHID Water numerical engine). Only the Lagrangian module is optional, if you simulate the dispersion simply in the far field. The near field model is activated in the Lagrangian module. Please keep in mind that before you run any dispersion simulation, you need to setup, calibrate and validate the 3D hydrodynamic model.

    Once you have the hydrodynamic model ready, you can activate the Lagrangian module (as described in this thread) and define the parameters of the discharge (characteristics of the outfall and the effluent). Model results for the near field will be output and will provide you information about the initial dilution, position and length of the plume, its velocity etc. You can then use this information and run a Eulerian simulation, where you use the near field output results, process them to setup a Eulerian discharge using the Discharges module and compute the far field dispersion of the plume taking into account baroclinicity (density driven currents) - see available options in Hydrodynamic setup. 

    I hope this helps to clarify some aspects. Please let me know if you have any other specific questions regarding this topic. 

    Kind regards,
    Luis