CMS-Flow Boundary Conditions

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CMS-Flow Boundary Conditions window

CMS-Flow has five types of boundary conditions which are listed and discussed below. The figure below shows the CMS-Flow Boundary Conditions window in SMS. All CMS-Flow boundary conditions are forced at the edges of the domain by use of cellstrings defined with the Surfacewater Modeling System (SMS). Cellstrings can either be created manually or using the SMS tool called Generate Along Boundary which is found under the Cellstring menu.


Land

The land boundary conditions is equivalent to a zero flux boundary condition. The land boundary condition is the default boundary condition when a cell string is created. It is not necessary to define land boundaries in the interior of the CMS-Flor domain, since land boundarys will automatically be detected by CMS-Flow based on the local water depths and the presence of inactive land cells.

Flow Rate-Forcing

The flow rate boundary condition specifies a time series of water fluxes in units of m^3/s per cell.

NOTES:

  • Total flow rate specified is divided between the total number of cells in the cellstring with each carrying a portion of the total.
  • This boundary type may only be specified along cell strings which are straight.
  • The sign of the flow rate curve is dependent on the direction of flow with respect to the origin (always lower-left hand corner of the grid).
This guide should assist in proper assignment:
    • Flow rate from the East - Negative value
    • Flow rate from the West - Positive value
    • Flow rate from the North - Negative value
    • Flow rate from the South - Positive value

Water Surface Elevation Forcing

Two types of Water Surface Elevation Forcing exist for CMS-Flow. Once a water surface elevation curve (or series of curves) is applied, the user is able to display the curve information graphically.

1. User defined curve (single time series curve for each cell string)

User creates a cellstring for the given boundary and defines a time series curve. The value for each time on this curve is applied to all cells along the designated cellstring. The time series curve may be specified by either importing an SMS *.xys file, copying tabular data into SMS, or manually entered the time series information in SMS.


2. Extract from data set (time series curve for each cell on cell string)

User creates a cellstring for the given boundary and extracts multiple time series curves from a dataset or database. Each cell along the cellstring is given its own time-series curve information. Examples are:

  • Extraction of water surface elevation values from a larger domain solution (ie. Larger CMS-Flow or ADCIRC grid)
  • Extraction of tidal constituent information from a tidal database, from which a water surface elevation curve can be generated.


Figure 1. Selecting the cellstring along the ocean boundary, and clicking on
  • Tidal Boundary Condition

1. Open one of the generated grids and select the Select a Cellstring button, rt-click the blue cellstring along the ocean boundary (if this cannot be selected it is because all cellstrings were deleted; this can be regenerated by clicking and clicking around the ocean cells or selecting Cellstring and Generate Along Boundary), select Assign BC (Figure 19),

2. Select the WSE-forcing boundary condition, and click curve undefined (Figure 19)


Figure 2. Top: is the blank XY Series Editor; Bottom: after the data is pasted in.

3. Open the excel file (SandHook_vs_Belmar.xls) in the Hands-on/Example 1 - Shark River Inlet/Tide folder, and select the time series in yellow for Sandy Hook with the time in hours on the left, and paste it into the XY Series Editor (Figure 20),

4. Zoom in on the graph on the right (Figure 20) to view the data up close,

5. Click export to save the xys (time series file) of the tide for use in other of the Shark River grid’s cellstrings, and save in the Tide folder, click OK when finished inspecting the pasted data, click OK.

6. Save the CMS-Flow Simulation File (.cmcards) in the original folder this alternative was saved in, and the new cellstring information will be saved with the card file.


Tidal Constituent Forcing

Tidal Constituent Forcing window in SMS

CMS-Flow as the option of forcing with a harmonic tidal water surface elevation. To assign a boundary as a tidal boundary:

  1. Select a cellstring
  2. Click under CMS-Flow | Assign BChttp://cirp.usace.army.mil/CIRPwiki/index.php?title=CMS-Flow_Boundary_Conditions&action=edit...
  3. In the CMS-Flow Boundary Conditions window, click on Tidal constituent-forcing, and click OK.
  4. Open the CMS-Flow Model Control window and click on the tab labeled Tidal.
  5. Enter the amplitudes and phases of the tidal constituents. Note that the same amplitude and phase are applied to entire cellstring and click OK

Tidal constituents used in CMS

Constituent Speed Constituent Speed Constituent Speed Constituent Speed
SA* 0.041067 SSA* 0.082137 MM* 0.54438 MSF* 1.0159
MF* 1.098 2Q1* 12.8543 Q1* 13.3987 RHO1* 13.4715
O1* 13.943 M1* 14.4967 P1* 14.9589 S1* 15.0
K1* 15.0411 J1* 15.5854 OO1* 16.1391 2N2* 27.8954
MU2* 27.9682 N2* 28.4397 NU2* 28.5126 M2 28.9841
LDA2* 29.4556 L2* 29.5285 T2* 29.9589 S2 30
R2* 30.0411 K2 30.0821 2SM2* 31.0159 2MK3* 42.9271
M3* 43.4762 MK3* 44.0252 MN4* 57.4238 M4 57.9682
MS4* 58.9841 S4* 60.0 M6 86.9523 S6* 90.0
M8* 115.9364

* Only available through advanced cards for CMS >v4.0


Water Surface Elevation and Velocity Forcing

Users are able to extract both water surface elevations and velocity components from a larger domain solution (ie. Larger CMS-Flow or ADCIRC grid).

Documentation Portal

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