Sediment Transport with Particle Tracking

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Particle Tracking

The TUFLOW Particle Tracking Module (PTM) allows the 2D or 3D simulation of discrete Lagrangian particles as they are transported by the flow field (or other drivers such as wind or waves). Particle behavior such as settling, buoyancy, decay, sedimentation and re-suspension can all be simulated. It can be run in conjunction with the sediment transport module to simulated the fate and age of sediment particles within the hydraulic model.

In this optional exercise we will take the existing FMA2_SED_003 model and add some particle tracking to track the input of particles.

Copy and paste the existing FMA2_SED_003.fvsed file and rename as FMA2_SED_003a.fvsed.

Under the Boundary Conditions Block add the following particle tracking block to reference a particle tracking file that we will generate.

!PARTICLE TRACKING INPUT
Particle Tracking Control File == FMA2_SED_003a.fvptm	

In the output commands block, under the current specification for the XMDF file add the following block to output results to a netcdf file. This will output hydraulic parameters, sediment transport parameters as well as results from the particle tracking module.

output == netcdf
      output parameters == h,v,d, Rhow, Taub, TauC, PTM_1, PTM_2, PTM_BED_2
      output interval == 900.
end output

Save and close the file.

Generate a new file called FMA2_SED_003a.fvptm. This is where we will generate the characteristics of our particle tracking module. We will use the same sediment characteristics that we have already applied to the sediment transport model. Add the following commands

! PTM to assess fate of STP plume - TEST POLYGON SEEDING ! use nodestring definition from HD model to allow particles to leave model domain. Open boundary nodestring == 2  ! downstream tidal boundary

!TIME COMMANDS !_________________________________________________________________ lagrangian timestep == 120. ! seconds eulerian timestep == 120. ! seconds

! Sediment Transport COMMANDS (required if a particle group interacts with bed) bed roughness model == ks bed roughness parameters == 0.01,0.01 ! ksc, ksw

!Global COMMANDS Nscalar == 1

!PARTICLE GROUP COMMANDS !_________________________________________________________________

Group == fineSed

   d50 == 0.000002
   particle density == 2650
   Settling model == constant
   settling parameters == 0.0002 !(m/s)
   deposition model == ws0
   Erosion Model == Mehta	
   Erosion parameters == 0.1, 0.5, 0.5 !Er, taucr, alpha

End Group

Group == Gravel

 d50 == 0.032
  particle density == 2650
  Settling model == constant
  settling parameters == 0.6 !(m/s)
  Critical stress model == Soulsby
  Bed load model == MPM_Shimizu
  Bed load parameters == 8.0, -1 ,1.5	

End Group

!_________________________________________________________________

! This is required due to adding deposition and settling. Material == 0 Layer == 1 dry density == 1890.,1890 End layer

end material

!Upstream seed particles == point, 10796.514,8285.014 particle groups == fineSed, Gravel group mass == 100,100 end seed

! OUTPUT SETTINGS !_________________________________________________________________

output dir == ..\results\

output == ptm_netcdf

 output groups == all
 output parameters == age, state_age, mass, uvw, uvw_water, depth, water_depth
 output interval == 300.

end output