CMS-Flow

CMS-Flow is a component of the Coastal Modeling System (CMS). It is a finite-volume numerical engine which presently includes various two dimensional capabilities. Present features are:

• Hydrodynamics - water levels and current flow values under any condition of tide, wind, surge, waves and river flow
• Sediment Transport - as bedload, suspended load, and total load dependent on various transport algorithms
• Morphology Change
• Salinity Transport

For more information on the model itself, refer to the users manual published by USACE-ERDC.

Pre- and post-processing of CMS-Flow grids is accomplished with the Surface-water Modeling System (SMS), version 10.0 and later. The user can set up and edit computational grids, specify model parameters, define interaction of this model with the wave counterpart (CMS-Wave), launch the model and visualize the results.

The model is intended to be run on a project-scale, meaning the domain should only be on the order of 1-100 kilometers in length and width; however, future features will allow for more regional applications. The following sections describe the interface and make recommendations for the applications of the model.

Graphical Interface

The CMS-Flow Graphical Interface is contained in the Cartesian Grid Module as well as the Map Module and includes tools to create and edit a CMS-Flow simulation. The simulation consists of a geometric definition of the model domain (the grid) and a set of numerical parameters. The parameters define the boundary conditions and options pertinent to the model.

The interface is accessed by selecting the Cartesian Grid Module and setting the current model to CMS-Flow. If a grid has already been created for a CMS-Flow simulation or an existing simulation read, the grid object will exist in the Project Explorer and selecting that object will make the Cartesian grid module active and set the model to CMS-Flow. See Creating 2D Cartesian Grids for more information.

Using the Model / Practical Notes

For new simulations, users will create the CMS-Flow grid based on a conceptual model. The conceptual model includes:

• A CMS-Flow Coverage: this coverage defines the domain of the grid using a grid frame. The coverage also defines the location of land and water in the grid using one of three methods:
  • Land/Water cells defined based bathymetric values. CMS-Flow uses depths, so positive depth indicates water, negative depth indicates land. Cells with depth less than the negative value of the water surface are dry. This option requires a geometric survey that includes both the bathymetric area and the areas that could potentially be flooded. This is the most intuitive option and the preferred method if geometric data is available.
  • Land/Water interface defined by coastline arcs. This option allows the user to define, read or import arc definitions that delineate the water area. These arcs include an orientation. To the left of the arc is land, to the right is water. The user can select an arc and swap its orientation. All the area inside the grid frame on the "water" side of the arc must have elevations defined either from a survey, or by specification. Cells created on the "land" side of the arc will never be included in calculations (they are permanently dry). These arcs also include an attribute defining how cells spanning this interface are to be classified. They may be forced to be water (ocean preference), forced to be land (land preference) or split based on the percentage of the cell on each side of the arc (percent preference).
  • Land/Water interface defined by polygons. This option also requires the user to define arcs delineating the extents of the computational area. However, these arcs must be closed into polygons. Each polygon is specified to enclose land or water and cells are classified accordingly.

• An Area Property Coverage: this is an optional coverage or set of coverages which contain polygons of material types.

New Features/Capabilities

With the introduction of CMS-Flow version 3.75, several new features have been added. Below is a list of these new features/capabilities which link to additional pages of documentation.

• Multiple Processor Capability -- Animation
• Salinity Calculation
• Non-equilibrium Sediment Transport
• Subgrid Turbulence Model

More information to be added at a later time.

Case Studies / Sample Problems

The following tutorials may be helpful for learning to use CMS-Flow in SMS:

• Models Section
  • CMS - CMS-Flow

Links and References

• SMS Models page
• CMS-Wave

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• Sep 2008 Modeling of Morphologic Changes Caused by Inlet Management Strategies at Big Sarasota Pass, Florida [1]
• Jul 2007 ERDC/CHL CHETN-IV-69 Tips for Developing Bathymetry Grids for Coastal Modeling System Applications [2]
• Aug 2006 ERDC/CHL TR-06-9 Two-Dimensional Depth-Averaged Circulation Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change [3]
• Feb 2006 ERDC/CHL CHETN-IV-67 Frequently-Asked Questions (FAQs) About Coastal Inlets and U.S. Army Corps of Engineers' Coastal Inlets Research Program (CIRP) [4] Updated FAQ Website [5]
• May 2005 ERDC/CHL CHETN-IV-63 Representation of Nonerodible (Hard) Bottom in Two-Dimensional Morphology Change Models [6]
• May 2004 ERDC/CHL TR-04-2 Two-Dimensional Depth-Averaged Circulation Model M2D: Version 2.0, Report 1, Technical Documentation and User’s Guide [7]
• Dec 2003 ERDC/CHL CHETN-IV-60 SMS Steering Module for Coupling Waves and Currents, 2: M2D and STWAVE [8]