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Lagrangian sedimentation methods (OPENFLOWS FLOOD)

Nikolas Souza
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Dear all,

I have been struggling to manage Lagrangian Module sediment density dynamic. As I couldn't find information on how to run plastic simulation in openflows flood, I have been trying using cohesive sediments as an input, trying to observe the sedimentation (Z points) from the output (HDF file).

I have noticed that OpenFlows Flood owns few sedimentation models (stokes/imposed/density dynamic/FergusonChurch2004 / Secondary Clarifier). I have been studying how they apply to plastic sedimentation and also trying to observe how to manage to find its sedimentation based on the water column density. The thing is: no matter how I change D50 and D50_density on Lagrangian Module, I can't manage to find difference in the Z Position output in Lagrangian.HDF5 file. I wouldn't like to impose settling velocity. In fact, I wish Openflows would work it out based on density difference between the water column and the particle. Is there a recommended way to work it out?

Regards,

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    Hi Nicolas,

    OpenFlows FLOOD does not have any explicit way to simulate plastic transport, dispersion and sedimentation, but it's possible to use the approach you mention using the Lagrangian module, but it is still a workaround.

    Could you post/send your model files for us to have a look and see what's the problem?

    Thanks and regards,
    Luis

  • Offline in reply to Luis Fernandes

    Hello Luis,

    Thanks for the reply.

    In fact, I have used a basic hydrodynamic with Lagrangian. Only Stokes sedimentation process showed some interesting result. The other two I have tried have showed constant Z value.

    !Output Options
    OUTPUT_TIME : 0 60.
    TIME_SERIE : 0

    !Origin Block
    <BeginOrigin>
    ORIGIN_NAME : TEST
    OLD : 0
    EMISSION_SPATIAL : Point
    EMISSION_TEMPORAL : Instantaneous
    POINT_VOLUME : 0.9
    NBR_PARTIC : 60
    DT_EMIT : 5
    !FLOW : 0
    FLOAT : 0
    MOVEMENT : SullivanAllen
    POSITION_COORDINATES : -43.7833 -23.1248
    SEDIMENTATION : Secondary Clarifier
    VARVELHX : 0.0015
    VARVELH : 0.003
    !VARVELVX : 0.0015
    !VARVELV : 0.003

    TURB_V : Profile
    ADVECTION_Z : 1
    D50 : 1000
    D50_DENSITY : 0.05


    EMISSION_ON : 1
    SURFACE_EMISSION : 0
    DEPTH_METERS : 1.5 


    COMPUTE_AVERAGE_POSITION : 1


    !COMPUTE_BUOYANCY : 1 #not working, whatever I do I couldn't make it work.
    DENSITY_METHOD : 2


    !Lagrangian Property Block

    <<BeginProperty>>
    NAME : sediment
    UNITS : psu
    CONCENTRATION : 1.
    AMBIENT_CONC : 1.0
    OUTPUT_HDF : 1
    !D50 : 5
    <<EndProperty>>

    <<BeginProperty>>
    NAME : cohesive sediment
    UNITS : mg/l
    CONCENTRATION : 1
    AMBIENT_CONC : 1.0
    OUTPUT_HDF : 1
    TIME_SERIE : 0
    !D50 : 5
    <<EndProperty>>

    <EndOrigin>

    <BeginOrigin_Clone>
    !INSTANT_PARTIC_EMIT : 2019 8 6 3 0 0
    CLONE : TEST
    ORIGIN_NAME : P01
    GROUP_ID : 1
    !IMMERSION_RATIO : 70
    POSITION_COORDINATES : -44.0251 -23.1525
    !OIL_TIMESERIE : A02
    !TIME_SERIE_LOCATION : 1
    SEDIMENTATION : Stokes
    DEPOSITION : 1
    <EndOrigin_Clone>

    <BeginOrigin_Clone>
    !INSTANT_PARTIC_EMIT : 2019 8 6 3 0 0
    CLONE : TEST
    ORIGIN_NAME : P02
    GROUP_ID : 1
    !IMMERSION_RATIO : 70
    POSITION_COORDINATES : -44.0797 -23.0449
    !OIL_TIMESERIE : A02
    !TIME_SERIE_LOCATION : 1
    SEDIMENTATION : Density Dynamic
    DEPOSITION : 1
    <EndOrigin_Clone>

    Once again, thanks a lot.

    Let me know if that is the way you wanted to see the model or if you'd rather have it fully uploaded as a .ows

    Regards,

  • Offline in reply to Nikolas Souza

    Hello,

    "Stokes" computes the settling velocity based only on the size of the particles (D50). It does not take into account the water density and the density of the particle. 

    "Density Dynamic" is actually used for oil droplets (so not valid for your case). 

    "Secondary Clarifier" is use to simulation sedimentation in waste water treatment sedimentation tanks, so also not applicable. 

    "FergusonChurch2004" is also computes the settling velocity based only on the size of the particles (multiple size classes), and does not take into consideration water or particle density. 

    So, Stokes and FergusonChurch2004 maybe the best approach here, although not exactly what you wanted.

    Kind regards,
    Luis

  • Offline in reply to Luis Fernandes

    The information above has been added to the following link: Lagrangian sedimentation methods in OpenFlows FLOOD.

    Regards,

    Scott

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