SMS:RMA2

RMA2 Model Info Model type Two-dimensional depth averaged finite element hydrodynamic numerical model. Computes water surface elevations and horizontal velocity components for subcritical, free-surface flow in two dimensional flow fields. Developer Resource Management Associates United States Army Corps of Engineers (USACE) Web site RMA2 web site Tutorials General Section Mesh Editing Observation Overview Sensitivity Models Section RMA2 RMA2 Steering

RMA2 is a 1D/2D hydrodynamic model using the finite element method. RMA2 was written by Ian King and is maintained by the Army Corp of Engineers Engineering Resource Development Center (ERDC). RMA2 has been applied to multi-dimensional problems since the mid 1970s. As such, it was one of the first widely used multi-dimensional hydrodynamics engine applied to riverine and estuarine applications. The current interface to RMA2 in the Surface-water Modeling System originated as a program named FastTABS.

Functionality

RMA2 has these capabilities:

• Compute water levels and velocities for a 2D mesh structure
• 1D elements (trapezoidal shape)
• 1D flow control structures
• Allow elements to wet and dry
• 2D structures are permitted in version 4.50 or higher (US Army Corps of Engineers employees only)
• Account for effects of the earth's rotation ( Coriolis effect)

• Accepts a wide variety of boundary conditions including:

• Discharge by node/element/ or line
• Tidal radiation boundary conditions by line
• Discharge as a function of elevation by line
• Water surface elevation along a line
• Apply wind stress either

• Uniformly over the model domain; constant or time-varying
• As a storm; front or tropical cyclonic event (time-varying)

• Read an STWAVE radiation stress file to incorporate wave induced currents

• Identify errors in the computational mesh specification
• Accept either English or standard SI units
• Restart (Hotstart) the simulation from a prior RMA2 run and continue
• Account for Marsh Porosity wetting and drying (wetlands)

• Employ either direct or automatic dynamic assignment of Manning's n-value by water depth
• Employ user selectable manual or automatically assigned turbulent exchange coefficients
• Compute flow across continuity check lines.
• Revisions within a time step (both coefficients and/or boundary conditions)

Using the Model / Practical Notes

• RMA2 Spindown Steering (Incremental Loading)
• RMA2 2D Control structures are only available to employees of the US Army Corps of Engineers.
• The TABS models are built to expire after a set date. The latest version can be downloaded from the Software Updates section of the Aquaveo website.
• According to the RMA2 model documentation, "Because of lack of experience in using storms in a simulation, including storms in simulations remains experimental."
• Boundary condition time series curves are resampled by the model based on the time step. If changing the time step, a user may want to re-enter the time series curve since SMS will automatically resample the curve and resampling the curve multiple times may result in a loss of important information.

Graphical Interface

SMS provides a graphical interface that is designed to allow users to visualize the projects they are creating, easily modify project parameters, and view the solutions produced by the RMA2 model. See RMA2 Graphical Interface for more information.

The RMA2 Graphical Interface contains tools to create and edit an RMA2 simulation. The simulation consists of a geometric definition of the model domain (the mesh) 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 2D Mesh Module and setting the current model to RMA2. If a mesh has already been created for a RMA2 simulation or an existing simulation read, the mesh object will exist in the Project Explorer and selecting that object will make the 2D Mesh module active and set the model to RMA2. See the Mesh Module documentation for guidance on building and editing meshes as well as visualizing mesh results.

The interface consists of the 2D Mesh Module Menus and tools augmented by the RMA2 Menu. See RMA2 Graphical Interface for more information.

Saving RMA2

When completing the File | Save As... command, the following files get saved in the *.sms

• *.mat referenced to new save location
• *.sim referenced to new save location

Related Topics

• SMS Models Page
• TABS Models
• RMA4
• Nodal Transition Dialog
• Roughness Options Dialog
• Rainfall Values Dialog

External Links

• CHL RMA2 Website [1]
• CHL RMA2 Frequently Asked Questions [2]
• Users Guide To RMA2 WES Version 4.5 [3]
• Users Guide to RMA2 Version 4.35 [4]
• MERGAVE – Utility for Merging RMA2 Solution Files [5]