| Product(s): | OpenFlows FLOOD |
| Version(s): | 10.XX.XX.XX |
| Area: | Modeling |
This article briefly explains how to simulate the transport and dispersion biogeochemical oxygen demand (BOD) in OpenFlows FLOOD with the 3D coastal modelling engine MOHID Water using a Lagrangian approach.
Overview
To implement a BOD dispersion simulation, you must first implement, run and validate your hydrodynamic model. Then to activate the Lagrangian module, go to the Model input options and set the "Enable Lagragian Module" to True.
Then in your simulation properties (select simulation, right-click and select Properties), and add the Lagrangian and WaterQuality modules to the left hand-side list of Modules in Simulation.
Lagrangian module setup
To setup a Lagrangian BOD discharge set the following commands to the Lagrangian input options file.
Set the Lagrangian model integration time step (in seconds):
DT_PARTIC : 30
Set the output time step (in seconds). 2 values must be defined. The first is the time of the first output and the second is the output frequency.
OUTPUT_TIME : 0 600.
For each discharge a block <BeginOrigin>/<EndOrigin> must be defined. For a continuous discharge with constant flow (FLOW) set the following commands. POSITION_COORDINATES sets the coordinates (same as used in the computational grid) of the discharge. In the <<BeginProperty>><<BeginEndProperty>> blocks you must define temperature, salinity, oxygen and BOD concentration of the effluent. AMBIENT_CONC sets the concentrations in the ambient water. If ommited, the model will consider the concentrations computed by the WaterProperties module.
WQM_DATA_FILE sets the path to the WaterQuality input data file. TVOL200 sets the time for doubling the Lagrangian tracer volume (a parameterization of ambient water entrainment). Typical values range from 2 to 4 hours.
<BeginOrigin>
ORIGIN_NAME : Discharge_1
OLD : 0
EMISSION_SPATIAL : Point
EMISSION_TEMPORAL : Continuous
DT_EMIT : 30
FLOW : 0.5
NBR_PARTIC : 1
FLOAT : 0
MOVEMENT : SullivanAllen
VARVELHX : 0.05
VARVELH : 0.001
TURB_V : Constant
VARVELVX : 0.001
VARVELV : 0.000
POSITION_COORDINATES : -9.1395357 39.5119165
DEPTH_CELLS : 0.5
TVOL200 : 10800.
VOLUME_INCREASE : Double
VOLFAC : 10
WQM_DATA_FILE : ..\data\WaterQuality_1.dat
<<BeginProperty>>
NAME : salinity
UNITS : psu
CONCENTRATION : 0.1
AMBIENT_CONC : 0.1
OUTPUT_HDF : 1
<<EndProperty>>
<<BeginProperty>>
NAME : temperature
UNITS : degC
CONCENTRATION : 20.
AMBIENT_CONC : 20.0
OUTPUT_HDF : 1
<<EndProperty>>
<<BeginProperty>>
NAME : oxygen
UNITS : mg/l
CONCENTRATION : 8
AMBIENT_CONC : 8.0
OUTPUT_HDF : 1
<<EndProperty>>
<<BeginProperty>>
NAME : biochemical oxygen demand
UNITS : mg/l
CONCENTRATION : 16
AMBIENT_CONC : 4
OUTPUT_HDF : 1
<<EndProperty>>
<EndOrigin>
The WaterQuality file must be set with the following commands:
DTSECONDS : 60.
NITROGEN : 0
PHOSPHOR : 0
PHYTO : 0
ZOO : 0
OXYGEN : 1
DIATOMS : 0
SILICA : 0
BACTERIA : 0
CILIATE : 0
BOD : 1
LARVAE : 0
AGE : 0
EXPLICIT : 1
--------------BOD----------------------------------------
BODCOEF : 1.047 !BOD oxidation coefficient
BODREF : 0.18 !Reference BOD oxidation
BODOSSAT : 0.5 !Oxygen limitation half-saturation constant
--------------OXYGEN----------------------------------------
OCRATIO : 2.67 !Oxygen/Carbon Ratio in CO2
PHOTOSOC : 2.67 !Photosynthesis Oxygen/Carnon Ratio
NITONRAT : 3.43 !Oxygen/Nitrogen ratio in Nitrate
PHOSOPRAT : 2.06 !Oxygen/Nitrogen ratio in Phosphate
PLANK_OC_RAT : 2.67 !Plankton Oxygen/Carbon Ratio
ZOCRATIO : 2.67 !Mesozooplankton respiration O:C Ratio
CILOCRATIO : 2.67 !Microzooplankton respiration O:C Ratio
BACTRATIOOC : 1.4 !Bacteria Oxygen/Carbon Ratio (Redfield)
OMRATIONC : 0.18 !Organic matter Nitrogen/Carbon Ratio (Redfield)
OMRATIOPC : 0.024 !Organic matter Phosphorus/Carbon Ratio (Redfield)
MINOXYGEN : 1e-5 !Minimum oxygen concentration for growth