RMA4 - The RMA4 model is a water quality transport model, modeling, modelling software - constituent transport
RMA4 DESCRIPTION
RMA4
RMA4 is a one-dimensional and two-dimensional finite element depth-averaged numerical model of constituent transport. RMA4 can accommodate all hydrodynamic options available in RMA2 including one-dimensional control structures. It reads an RMA2 hydrodynamic solution and an RMA2 geometry as input. It calculates the advective diffusion equations to model up to six non-interacting constituents. SMS supports postprocessing only for RMA4.
RMA4 is a general purpose model designed to investigate physical processes which are responsible for the distribution of pollutants in the environment and testing the effectiveness of remedial control measures. The methodology is restricted to one-dimensional and two-dimensional systems in which the concentration distribution in the third dimension is assumed uniform.
RMA4 has the following capabilities:
- Reads one-dimensional and/or two-dimensional geometry files from GFGEN, and modifies as needed.
- Restarts (Hotstarts) the simulation from a prior RMA4 run and continues.
- Reads one-dimensional and/or two-dimensional hydrodynamic solutions from RMA2 or allows manual specification of the velocity field.
- Appropriately handles marsh porosity and wetting and drying from RMA2.
- Handles all one-dimensional flow control structures that are available in RMA2.
- Computes mass flux at continuity check line points.
- Accepts boundary condition concentrations by node, line, or mass loading.
- Models up to six constituents as conservative or non-conservative using a first order decay.
- Permits temporary storage of resolution files designed to speed up the solution calculations when the velocity file recycles such as during a simulation of many repeated tidal cycles.
RMA4 has the capability to simulate advection-diffusion in the aquatic environment.
The formulation of RMA4 is limited to one-dimensional (cross-sectional averaged) and two-dimensional (depth-averaged) situations in which the concentration is fairly well mixed in the vertical. It will not provide accurate concentrations for stratified situations in which the constituent concentration influences the density of the fluid. The accuracy of the transport model is dependent on the accuracy of the hydrodynamics (e.g., as supplied from RMA2). If you need to model water quality transport in three-dimensional domains, refer to models such as RMA11. Note that RMA4 currently only accepts System International (SI) Metric units.
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