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DHI MIKE 3 Flow Model FM User Manual

Particle tracking module
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MIKE 3 Flow Model FM
Particle Tracking Module
User Guide
MIKE 2017

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  • Page 1 MIKE 3 Flow Model FM Particle Tracking Module User Guide MIKE 2017...
  • Page 3 DHI. For details please refer to your 'DHI Software Licence Agreement'. LIMITED LIABILITY The liability of DHI is limited as specified in Section III of your 'DHI Software Licence Agreement': 'IN NO EVENT SHALL DHI OR ITS REPRESENTATIVES...
  • Page 4 Particle Tracking Module FM - © DHI...

  • Page 5: Table Of Contents

    CONTENTS ABOUT THIS GUIDE ....... . . Purpose ........Assumed User Background .
  • Page 6 ..........47 Particle Tracking Module FM - © DHI...

  • Page 7: About This Guide

    Purpose ABOUT THIS GUIDE Purpose The main purpose of this User Guide is to enable you to use the MIKE 3 Flow Model FM, Particle Tracking Module, for applications involving the simulation of transport and fate of dissolved and suspended substances discharged or accidently spilled in lakes, estuaries and coastal areas or at the open sea.

  • Page 8: Validation Window

    F1-key on the keyboard after opening the editor and activating the spe- cific property page. Open the Online Help system for browsing manually after a specific  help page: Open the Online Help system by selecting “Help Topics” in the main menu bar. Particle Tracking Module FM - © DHI...

  • Page 9: Introduction

    General Description INTRODUCTION General Description The Particle Tracking module of MIKE 3 Flow Model FM is used for modelling the transport and determine the fate of dissolved, suspended and sedimented substances discharged or accidently spilled in lakes, estuaries and coastal areas or at the open sea.
  • Page 10 INTRODUCTION Monitoring of dredging works  Particle Tracking Module FM - © DHI...

  • Page 11: Getting Started

    Step-by-Step Training Guide A comprehensive training guide covering the Particle Tracking Module of the MIKE 21 Flow Model FM modelling system is also provided with the DHI Soft- ware installation.The objective of this training guide is to set up a Particle Tracking model for the Great Belt area from scratch and to calibrate the model to a satisfactory level.
  • Page 12 GETTING STARTED Particle Tracking Module FM - © DHI...

  • Page 13: Examples

    One of the best ways to get to know how to use a modelling system such as MIKE 3 Flow Model FM is through practical applications. Therefore examples are included which you can go through yourself and which you can modify to see the effects if one or other parameter is changed.

  • Page 14: Parameters

    An overall time step of 0.5 seconds is selected and the duration of the  simulation is 3 hours (21600 time steps). The horizontal eddy viscosity type has been chosen to Smagorintsky for-  mulation with a constant value of 0.28. Particle Tracking Module FM - © DHI...
  • Page 15 Corner Flow Example The bed resistance type has been defined by a constant roughness  height of 0.05 m. Initially the water surface is 0.0 m in the entire domain.  The upstream (south) boundary is defined by a constant water level of ...

  • Page 16: Results

    Note that due to the dispersion, two consecutive runs will not produce the exact same result. Figure 4.3 Time series of current speed Solid black line : P1 Stippled blue line: P2 Dotted green line: P3 Particle Tracking Module FM - © DHI...

  • Page 17: Files

    Dotted green line: P3 Figure 4.5 Particle tracks and instantanoeus location of particles at the end of sim- ulation. 4.2.5 Files The following data files (included in the PT\Corner folder) are supplied with MIKE 3 Flow Model FM, PT module:...
  • Page 18 EXAMPLES File name: Corner.mesh Description: Mesh file including the mesh and bathymetry File name: Setup_Corner.m3fm Description: MIKE 3 Flow Model FM specification file Particle Tracking Module FM - © DHI...

  • Page 19: Particle Tracking Module

    Classes PARTICLE TRACKING MODULE The Particle Tracking module calculates the transport and determine the fate of dissolved, suspended and sedimented substances discharged or acci- dently spilled in lakes, estuaries and coastal areas or at the open sea. Classes Particles are divided into different groups called classes. Each class has spe- cific properties regarding decay, settling/buoyancy, erosion, and dispersion that has to be specified separately.

  • Page 20: Particle Source Specification

    If the source definition causes a particle to be released above surface/below bed level, the position is set to the surface/bed respectively. Point source The location of a point source must be defined using one of two sub-types Particle Tracking Module FM - © DHI...
  • Page 21 Sources Fixed location  Moving location  For the Fixed location source option, i.e. the source is stationary during simu- lation time, you must specify the horizontal coordinates of the source point and its vertical position. For the Moving location source option, i.e. the source is moving along a defined path, you must specify a time series file (dfs0) that contains the hori- zontal coordinates and the vertical position of the source as a function of time.
  • Page 22 If particles are placed based on the total area then such ele- ments will not receive any particles! In this case the particles should be placed based on the sub-element count. By this every sub element has the same probability to receive a particle. Particle Tracking Module FM - © DHI...

  • Page 23: Remarks And Hints

    Sources Released class terms The format of the particle class information within the source can be specified Constant in time  Varying in time  For the case with the particles class source information varying in time you have to prepare a data file containing the value of the particle source (in the specified EUM unit for the class) before you set up the hydrodynamic simula- tion.

  • Page 24: Decay

    An example could be decay of BOD (Biochemical oxygen demand). 5.3.2 Class decay The format of the decay factor can be specified as Particle Tracking Module FM - © DHI...

  • Page 25: Remarks And Hints

    Settling Constant (in time)  Varying in time  For the case with time varying decay rate you have to prepare a data file con- taining the decay rate. The data file must be a time series file (dfs0). The data must cover the complete simulation period.
  • Page 26 High levels of turbulence will decrease the floc size due to destruction of flocs. Flocculation Flocculation is when the concentration of sediment is high enough for the sediment flocs to influence each other’s settling velocity. This happens Particle Tracking Module FM - © DHI...
  • Page 27 Settling because collisions between flocs will increase floc size leading to higher set- tling velocities. In case of fine grained cohesive sediment (<0.006 mm), the size of the parti- cles and thereby the settling velocity will depend on the rate of flocculation. With low concentrations of suspended sediment, the probability for collision between the cohesive particles is low and the settling velocity will be close to the settling velocity for a single grain.

  • Page 28: Class Settling

    Depending on the choice of settling type you must specify the settling velocity data and the settling parameters. Settling velocity data The format of the settling velocity coefficient for particles in suspension can be specified as: Particle Tracking Module FM - © DHI...

  • Page 29: Dispersion

    Dispersion Constant (in time)  Varying in time  If constant settling velocity is selected, the settling velocity will be kept con- stant and independent of the concentration of sediment throughout the simu- lation. For the case with time varying settling velocity coefficient you have to prepare a data file containing the velocity coefficients.

  • Page 30: Dispersion Specification

    The area in the data file must cover the model area. If a dfsu-file is used, a piecewice constant interpolation is used to map the data. If a dfs3-file is used, a bilinear interpolation is used to map the data. Particle Tracking Module FM - © DHI...

  • Page 31: Recommended Values

    Erosion 5.5.2 Recommended values When more sophisticated eddy viscosity models are used, as the Smagorin- sky or k- models, the scaled eddy formulation should be used. , where  The scaling factor can be estimated by 1/ is the Prandtl number. To be consistent with the empirical constants for the k-...

  • Page 32: Drift Profile

    This will result in an addi- tional acceleration of the particle in a direction relative to the wind turned with a wind drift angle caused by coriolis forces. Particle Tracking Module FM - © DHI...

  • Page 33: Class Drift Profile

    Drift Profile 5.7.2 Class drift profile The different drift profile types can be combined in the following ways: Use raw data from hydrodynamics  Use bed shear profile  Use surface wind acceleration  Use bed shear profile and surface wind acceleration ...

  • Page 34: Hydrodynamic Conditions

    Wind induced profile can only be applied for 2D simulations. Hydrodynamic conditions If the Hydrodynamic Module is not included in the simulation you have to pro- vide the flow information using these settings. The Particle Tracking module Particle Tracking Module FM - © DHI...

  • Page 35: Temperature

    Temperature will then run in a so called stand-alone mode, using an external flow field. The flow information can be read from both unstructured (dfsu) or gridded (dfs2/dfs3) data files. The data files need to cover the model area and span over the entire simulation period.

  • Page 36: User Specified Salinity

    For the case with values varying in domain you have to prepare a data file containing the information before you set up the hydrodynamic simulation. The file must be a 2D unstructured data file (dfsu) or a 2D grid data file (dfs2). Particle Tracking Module FM - © DHI...

  • Page 37: Bed Roughness

    Bed Roughness The area in the data file must cover the model area. If a dfsu-file is used, a piecewise constant interpolation is used to map the data. If a dfs2-file is used, a bilinear interpolation is used to map the data 5.12 Bed Roughness The bed roughness is used in the Particle Tracking module if the Drift Profile...

  • Page 38: User Specified Bed Roughness

    2D unstructured data file (dfsu) or a 2D grid data file (dfs2). The area in the data file must cover the model area. If a dfsu-file is used, a piece- Particle Tracking Module FM - © DHI...

  • Page 39: Outputs

    Outputs wice constant interpolation is used to map the data. If a dfs2-file is used, a bilinear interpolation is used to map the data. Furthermore a soft start interval must be speficied. 5.14 Outputs Standard data files with computed results from the simulation can be speci- fied here.
  • Page 40  selected variable are saved on separate lines in the file In compressed format the values of the xyz-coordinates and each  selected variable are saved in the same line in the file Particle Tracking Module FM - © DHI...
  • Page 41 Outputs Figure 5.1 Example of data in XML file using uncompressed particle format Figure 5.2 Example of data in XML file using compressed particle format Treatment of flood and dry For 2D and 3D field parameters the flood and dry can be treated in three dif- ferent ways Whole area ...
  • Page 42 In case the mesh is a combined sigma-z level mesh, the number of active layers may vary in the domain. An example is shown in Figure 5.3. Particle Tracking Module FM - © DHI...
  • Page 43 Outputs Figure 5.3 Example of layer numbers in point output specification in case of com- bined sigma-z level mesh. Line series You must specify the first and the last point on the line and the number of dis- crete points on the line. The geographical coordinates are taken from the dia- log or from a file.
  • Page 44 The layer number(s) selected for the volume output are numbered 1 at the lowest layer and increase upwards. In case of a combined sigma-z level mesh only the elements containing water are saved in the output. An exam- ple is shown in Figure 5.4. Particle Tracking Module FM - © DHI...

  • Page 45: Output Items

    Outputs Figure 5.4 Example of layer numbers in volume output specification in case of combined sigma-z level mesh. 5.14.2 Output items 2D field variables You can select basic output variables and additional output variables. The basic variables consist of derived concentrations of the included classes. For each class, all the particles of the class are distributed according to the computational mesh, and the summarized mass of particles in each element is divided with the volume of the element cell to estimate the concentration in...
  • Page 46 Note that the two basic variables only differs in the bottom layer (layer 1) where some of the material may be sedimented. The additional variables are U Velocity  V Velocity  W Velocity  Particle Tracking Module FM - © DHI...

  • Page 47: Index

    INDEX...
  • Page 48 Settling velocity ... . . 28 User background ... . . 7 Z-Range output ... . . 46 Particle Tracking Module FM - © DHI...

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