SMS:CMS-Flow Model Control 11.2

The CMS-Flow Model Control dialog allows the user to view and edit the current parameters that affect how CMS-Flow runs and what options are to be included in the current simulation. The dialog includes nine tabs which partition the parameters into related groups. The tabs and their related parameters include:

General

CMS-Flow Model Control dialog

This dialog allows the user to specify general flow model parameters, controlling which model options the simulation will employ. The controls include:

Time Control

In this section the user can set the starting time, duration and hydraulic time step. The Ramp duration defines the length of an incremental loading portion at the beginning of the simulation. Controls include:

• Start date and time
• Simulation duration or end date and time
• Ramp duration

Hot Start

These controls allow the user to specify a previously saved hot start file to be used as initial conditions or instruct CMS-Flow to save hot start files for future use.

• Initial conditions file
• Write Hot Start output file
• Time at which Hot Start output file should be written
• Automatic recurring Hot Start file
• Interval for writing recurring Hot Start file

See CMS-Flow Hot Start for more information.

Threads

CMS-Flow can take advantage of multiple processors using Open-MP parallelization technology. This control allows the user to specify the maximum number of threads that the engine should occupy.

Water Parameters

• Water temperature
• Water density

Parameters

• Depth to begin drying cells
• Include wall friction
• Latitude throughout grid

• Cell specific latitude
• Average latitude

Momentum Equation

• Include advective terms
• Include mixing terms

Solution Scheme

CMS-Flow now has two solution schemes. These include the traditional "explicit" scheme. This method requires that flow be tracked through each element, resulting in hydrodynamic time steps in the order of one to two seconds. The new option is an "implicit" scheme which uses finite volume technology, supports much larger time steps resulting in fewer time steps (shorter run times) and is identically mass conserving. When the implicit scheme is being used, one of the following matrix solver types should be specified.

• GMRES
• GAUSS-SEIDEL
• GAUSS-SEIDEL-SOR
• BICGSTAB

Sediment

CMS-Flow Model Control dialog showing the Sediment tab

Time steps Transport rate Morphologic Sediment Calculate sediment transport Use non-equilibrium transport Formulation Advection-diffusion Hard Bottom Create Dataset Select Dataset Delete Dataset D50 Create Dataset Select Dataset Delete Dataset

Salinity

CMS-Flow Model Control dialog showing the Salinity tab

This tab allows the user to specify model parameters relating to salinity modeling in CMS-Flow. The controls include:

Salinity

CMS-Flow includes the capability to simulate the diffusion of saline water in fresh water. This section includes controls to enable and initialize these calculations.

• Calculate salinity – Turn on the calculation of salinity concentrations in the CMS-Flow simulation.

Time Steps

• In addition to the time step specified in the general parameters tab for hydrodynamic calculations, the explicit model also allows the specification of longer time step for the salinity dispersion process.
• Transport rate – If salinity is enabled in this tab, and the solver option is set to "explicit" in the Flow tab, the user must specify a this time step. It must be larger than the hydrodynamic time step and is generally at least a factor of 20. The default transport rate time step is 60 seconds.

Initial Condition

Salinity transport requires that each cell have an initial value for salinity concentration (measured in ppt). CMS-Flow allows this value to start as a constant for each cell, in which case, during the initial (or ramp time)of the simulation the concentrations are distributing to natural values.

• Global concentration – This control allows the user to specify an initial concentration for the entire domain. The value 0.0 ppt (fresh water) is a commonly used value.
• Spatially varied – these controls allow the user to create or select a spatially varied dataset that will be used by CMS-Flow as the initial concentration at each cell. This dataset is editable by the user.
• Create Dataset

CMS-Flow Salinity Global Concentration dialog

• Select Dataset
• Delete Dataset

External Documentation

• Two-Dimensional Depth-Averaged Circulation Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change[1]

Tidal

CMS-Flow Model Control dialog showing the Tidal tab

Flow

This dialog allows the user to specify general hydrodynamic or flow model parameters, controlling which model options the simulation will employ. The controls include:

Hydrodynamic Time Step

This control allows the user to set the hydrodynamic time step for the model. If the explicit solution scheme is being used, a recommended timestep will be calculated based on grid cell size and depths.

Water Parameters

This section allows the user to specify various general parameters to be used by the simulation. This include:

• Water temperature
• Water density
• Depth to begin drying cells: This is a minimum depth of water before the model considers the cell to be dry. Shutting off cells when the depth drops below a tolerance avoids flutter of insignificant transfers of water. The recommended default value is 0.05 meters.
• Include advective terms
• Include mixing terms
• Include wall friction: Normally friction at the closed boundaries are ignored. The model can be instructed to include friction along these boundaries as if a wall exists there.
• Include stokes velocities

Bottom Friction Dataset

Friction datasets can be created and specified to define a spatially variable bottom roughness to provide a resistance to flow. This value has little impact in deep ocean applications but can be important in shallow regions. This is a user editable dataset. The available dataset types are:

• Mannings N
• Bottom friction coefficient
• Roughness height

A bed-slope friction coefficient toggle gives the option to specify a wave-current bottom friction type and a coefficient.

Turbulence Parameters

CMS-Flow now supports turbulence parameters.

• Model: Subgrid, Falconer, Parabolic, Mixing length
• Base value
• Current bottom coefficient
• Current horizontal coefficient
• Wave bottom coefficient
• Wave breaking coefficient

Wind/Wave

CMS-Flow Model Control dialog showing the Wind/Wave tab

This dialog allows the user to specify wind conditions. These are optional inputs to the engine.

Wind Data

The user can turn on the option to tell CMS to include wind calculations in the simulation. Wind is simulated in CMS-Flow as a spatially constant, but temporally varying quantity. The model does not currently support tropical cyclonic winds.

• Spatially constant

• Import from File...: Button allowing the user to import wind data from a file. The file must be in an "m2w" wind format.
• Velocity (m/s): Button which invokes a time series editor to specify the variation of wind velocity through time in the simulation.
• Direction (deg): Button which invokes a time series editor to specify the variation in direction of the wind through time in the simulation.
• Anemometer height (m)

• Meteorologic stations – This option allows the user to insert data for multiple locations

• Import from File...: Button allowing the user to import wind data from a file. The file must be in an "m2w" wind format.
• Coordinates (X,Y): Location of meteorologic station
• Velocity (m/s): Button which invokes a time series editor to specify the variation of wind velocity through time in the simulation.
• Direction (deg): Button which invokes a time series editor to specify the variation in direction of the wind through time in the simulation.
• Anemometer height (m)

• Temporally and spatially varying from file

• Navy fleet numeric with pressure
• OWI/PBL
• Single ASCII file

Navy fleet and ASCII files require the following input:

• Number of X values
• Number of Y values
• Minimum X location
• Maximum Y location
• Time increment
• Distance between X values
• Distance between Y values

OWI/PBL requires three different files:

• Oceanweather Wind File
• Oceanweather Pressure File
• Oceanweather XY File

For more wind file information, see: http://cirp.usace.army.mil/wiki/CMS-Flow_Wind_Forcing#Spatially_Variable_Wind_and_Atmospheric_Pressure.

Wave Data

CMS-Flow includes three options on how to use wave data.

• None – No wave data is imputed into the model.
• Single wave condition – The effects of waves are input to the model in the form of spatially varying datasets. These datasets must already exist on the grid. The user simply selects which dataset to use

• Height
• Period
• Direction
• Dissipation
• Stress gradients (vector dataset)
• Surface roller stress gradients (optional)

• Inline steering

• CMS-Wave file. Location of the grid file or the simulation file
• Steering Interval or automatic value
• Specify extrapolation distances. If checked this will write out FLOW_EXTRAPOLATION_DISTANCE and WAVE_EXTRAPOLATION_DISTANCE cards.
• Wave Water Level – Option to select Tidal, Last, or Tidal plus variation (default value).

Output

CMS-Flow Model Control dialog showing the Output tab

This dialog allows the user to specify global output options for the simulation. This controls the datasets created by the engine which consist of spatially and temporally varied quantities (values per cell at each output time value).

These output datasets are stored in an XMDF solution file.

Output Times Lists

Due to the potentially long simulation times, CMS-Flow does not output at a constant interval during the simulation. Instead, the user defines one or more lists of times. For each dataset output by the engine, the user selects one time list. The selected quantity will be saved at each time in the time list.

• Lists: CMS-Flow supports up to four different and individual sets of time values.
• Output Times: The times included in the selected time list are displayed in this window.
• Type: The user adds and removes times to/from a time list using the tools in the time type section.

Output Datasets

CMS-Flow can output each of the following datasets. For each group, a time list must be specified. The optional datasets may turned off/on by clicking on their checkboxes in the output dataset tree.

• Water surface elevation
• Velocity

• Current Magnitude (optional)
• Current Velocity

• Morphology

• Depth (through time)
• Morphology Change (optional)

• Transport

• Sediment Total-Load Concentration (optional)
• Sediment Total-Load Capacity (optional)
• Fraction Suspended (optional)
• Total Sediment Transport
• Salinity Concentration (optional)

• Waves

• Wave Height
• Wave Period
• Wave Height Vector
• Wave Dissipation (optional)

• Wind

• Wind Speed (optional)
• Wind Speed Vector

• Eddy Viscosity

Statistical Output

Statistical data can be written out for hydrodynamics, sediment transport, and salinity. This option is turned on by toggles, and a start time, increment, and end time must be specified.

Output Options

Output can be written out in ASCII format and using XMDF file compression. These options are turned on by toggle boxes. All datasets created by the model will be labeled with a simulation label and quantity label. An edit field allows specification of the simulation label.

Cells

CMS-Flow Model Control dialog showing the Cells tab

Time Series Observation Output U velocity V velocity Water surface (ETA) Output interval Row Rate Observation Output X direction Y direction Output interval Transport Observation Output X direction Y direction Output interval

Input

CMS-Flow Model Control dialog showing the Input tab

Bottom Friction Dataset Manning's n Bottom friction coefficient Roughness height (m) Create Dataset Select Dataset Delete Dataset Custom Input Datasets

Advanced Options

CMS-Flow Model Control dialog showing the Advanced tab

This dialog allows the user to specify experimental options when working with the model developers.

Advanced Cards

Model options not available in the interface can be specified in the CMS-Flow model control under the advanced tab. Each row in the spreadsheet will be saved as a different line in the *.cmscards file. The cards can be inserted and deleted using the insert and delete rows.

• The lines will be written out exactly as typed.
• The lines will be written out in the order in which they appear in the dialog.
• Any lines encountered in a *.cmscards file that is not recognized will appear in this list.
• Lines beginning with a "!" character are treated as comment lines and will be skipped over during a read.
• Comment lines are automatically generated and will not be preserved.
• All of these advanced cards will be grouped together at the bottom of the file regardless of where they appeared during reading.

See CMS-Flow Advanced Cards

Related Topics

• CMS-Flow