intro story D-Flow FM

 

D-Flow Flexible Mesh

D-Flow Flexible Mesh (D-Flow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D-2D-3D. Together with the familiar curvilinear meshes from Delft3D 4, the unstructured grid can consist of triangles, pentagons (etc.) and 1D channel networks, all in one single mesh. It combines proven technology from the hydrodynamic engines of Delft3D 4 and SOBEK 2 and adds flexible administration, resulting in:

  • Easier 1D-2D-3D model coupling, intuitive setup of boundary conditions and meteorological forcings (amongst others).
  • More flexible 2D gridding in delta regions, river junctions, harbours, intertidal flats and more.
  • High performance by smart use of multicore architectures, and grid computing clusters.
An overview of the current developments can be found here.
 
The D-Flow FM - team would be delighted if you would participate in discussions on the generation of meshes, the specification of boundary conditions, the running of computations, and all kinds of other relevant topics. Feel free to share your smart questions and/or brilliant solutions! 

 

=======================================================
We have launched a new website (still under construction so expect continuous improvements) and a new forum dedicated to Delft3D Flexible Mesh.

Please follow this link to the new forum: 
/web/delft3dfm/forum

Post your questions, issues, suggestions, difficulties related to our Delft3D Flexible Mesh Suite on the new forum.

=======================================================

** PLEASE TAG YOUR POST! **

 

 

Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 


Message Boards

sediment transport formulation problem

LF
Fan Liyang, modified 4 Years ago.

sediment transport formulation problem

Youngling Posts: 3 Join Date: 11/24/15 Recent Posts
Hello, everyone
recently I am working on an morphology simulation with 3D flow model, and my model doesn't include wave. i have some trouble with transport formulation input file .tra, hope someone could give me some advice. my questions are as follows:
1. since wave has not been considered in the model, i abandoned the default option"Van Rijn 1993 and chooses "Van Rijn 1984" as my non-cohesive sediment transport formulation. my first question is :is it neccessary to switch the default formulation because of no wave situation?(Van Rijn 1993 takes both current and wave into account)
2. after i swithced to "Van Rijn 1984", i made a test run. 3 non-cohesive sediment and one cohesive sediment are included in the .sed file. i made 3 different .tra file for different non-cohesive fractions. when i check the .diagnose file, i have found something ridiculous! the cohesive fraction was given a .tra file, actually i didn't make such difinition for cohesive fraction. the diagnose file reads:
##########################################################################
*** Start of transport formulation
Input file : 3d001.tra
Inputfile in traditional MOR-format.
Transport formula used = 7
Parameters
1.00000000000000
0.000000000000000E+000
3.000000000000000E-002
4.000000000000000E-003
*** End of transport formulation

Sediment fraction 1: Sediment-coase.sand
Sediment fraction 2: Sediment-medium.sand
Sediment fraction 3: Sediment-fine.sand
Sediment fraction 4: Sediment-mud
*** Start of sediment input
Sediment File Version: 02.00
Ref concentration : 0.1600E+04
Option Dss : 0
Sediment number : 1
Name : Sediment-coase.sand
Type : sand
RHOSOL : 0.2650E+04
sed. distribution : piecewise loguniform
SedD10 : 0.1125E-02
SedD50 : 0.1500E-02
SedDM : 0.1607E-02
SedD90 : 0.2250E-02
CDRYB : 0.1800E+04
Uniform IniThick : 0.5000E+01 [m]
FACDSS : 0.1000E+01
Transport formula :
Input file : coase.sand.tra
Inputfile in traditional MOR-format.
Transport formula used = 7
Parameters
1.00000000000000
0.000000000000000E+000
3.000000000000000E-002
0.170000000000000
Sediment number : 2
Name : Sediment-medium.sand
Type : sand
RHOSOL : 0.2650E+04
sed. distribution : piecewise loguniform
SedD10 : 0.2625E-03
SedD50 : 0.3500E-03
SedDM : 0.3749E-03
SedD90 : 0.5250E-03
CDRYB : 0.1450E+04
Uniform IniThick : 0.5000E+01 [m]
FACDSS : 0.1000E+01
Transport formula :
Input file : medium.sand.tra
Inputfile in traditional MOR-format.
Transport formula used = 7
Parameters
1.00000000000000
0.000000000000000E+000
3.000000000000000E-002
3.700000000000000E-002
Sediment number : 3
Name : Sediment-fine.sand
Type : sand
RHOSOL : 0.2650E+04
sed. distribution : piecewise loguniform
SedD10 : 0.5250E-04
SedD50 : 0.7000E-04
SedDM : 0.7498E-04
SedD90 : 0.1050E-03
CDRYB : 0.1400E+04
Uniform IniThick : 0.5000E+01 [m]
FACDSS : 0.7000E+00
Transport formula :
Input file : fine.sand.tra
Inputfile in traditional MOR-format.
Transport formula used = 7
Parameters
1.00000000000000
0.000000000000000E+000
3.000000000000000E-002
4.000000000000000E-003
Sediment number : 4
Name : Sediment-mud
Type : mud
RHOSOL : 0.2650E+04
CDRYB : 0.1000E+04
Uniform IniThick : 0.5000E+01 [m]
FACDSS : 0.1000E+01
Transport formula :
Input file : fine.sand.tra
Inputfile in traditional MOR-format.
Transport formula used = 7
Parameters
1.00000000000000
0.000000000000000E+000
3.000000000000000E-002
4.000000000000000E-003
SALMAX : 0.0000E+00
WS0 : 0.5000E-04
WSM : 0.5000E-04
*** End of sediment input
###################################################################################
3. after the test run finished, i have checked Settling velocity at some observation points with QuickPlot. i have found two confusing thing:i have set 6 layers in total ,but quickplot GUI "k" number shows 7;settling velocity presented in QuickPlot is different from .tra files. for example, "medium sand.tra" setup is shown below:
7 Number of transport formula IFORM
*--------------------------------------------------------
#7 Van-Rijn-1984
1 -Par 1- calibration coefficient Acal
0 -Dummy
0.03 -Par 2- Reference level
0.037 -Par 3- settling velocity ws
# End of specification of transport relation
settling velocity is set to be 0.037m/s, but result shows in quickplot are 0.048m/s.

waiting for your advice and best regards
Liyang
Qinghua Ye, modified 4 Years ago.

RE: sediment transport formulation problem (Answer)

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Liyang,

Since the settling velocity is defined at the cell boundary, when you have n layers, you always have n+1 layer boundaries. Thus you have n+1 settling velocities at one column and QUICKPLOT will read n+1 values.

For output settling velocity from QUICKPLOT is from computation from the diameter you specified, and the settling velocity input for VR84 is only used to compute sediment transport. That is why these 2 numbers are different. Very good you noticed this difference, but I would think you should match these 2 numbers in your input, as a modeller.

Regards,

Qinghua