SUNTANS

Criterion

Explanation

General Description

SUNTANS is an open-source 3-D circulation model developed at Stanford University that computes flows on an unstructured grid using a finite-volume method. SUNTANS is highly parallelized and designed to be used on large parallel computing clusters. SUNTANS is similar to the 3-D unstructured-grid UnTRIM model. It includes algorithms for sediment transport and surface wave effects on bottom stresses and flows. Various grids have been created for parts and the entirety of the Bay–Delta in the context of applications to the South Bay Salt Pond restoration as well as for detailed flow modeling in the Delta.

Model Domain

The model domain is flexible and can be specified by the user, and can include coastal, estuarine, lakes and river areas.

Developer

Stanford University

Hardware computing requirements

SUNTANS is highly parallelized and designed to be used on large parallel computing clusters.

Code language

C

Original application

SUNTANS is an unstructured-grid tool that adaptively simulates multiscale physics in the coastal ocean; specifically designed for coastal and estuarine processes. Early applications were to the San Francisco bay and Snohomish River estuary.

Public/proprietary and cost

The model source code is open source.

Physically or empirically based

Physically based

Mathematical methods used

SUNTANS computes flows on an unstructured grid using a finite-volume method, and implements two key approaches: (1) a semi-implicit free surface; and (2) a fractional step method to efficiently calculate the effects of nonhydrostatic pressures.

Input data requirements

Model developers recommend the grid generation package GAMBIT from Fluent, Inc. All input files are ASCII text files. Input data includes:

• Domain (grid parameters, bathymetry)
• Initial conditions (water level, salinity, water temperature, water velocity)
• Boundary conditions (inflows, outflows, water level, salinity, water temperature)
• Physical parameters (describing constants, viscosity, heat flux, sediment, tidal forces)
• Environmental parameters (wind speed and direction)

Outputs

A standalone GUI is provided to view results (but cannot output results to standard figure file formats). Model outputs are provided in ASCII or binary files. Model output includes: free surface, velocity vectors, salinity, temperature, nonhydrostatic pressure, eddy viscosity, scalar diffusivity, water depth.

Pre-processing and post-processing tools

Model developers recommend the grid generation package GAMBIT from Fluent, Inc. A standalone GUI is provided to view results (but cannot output results to standard figure file formats).

Representation of uncertainty

Uncertainty is not represented.

Prevalence

The model is used by the academic community, therefore most or all known applications are in the peer-reviewed literature.

Ease of use for public entities

SUNTANS is highly parallelized and designed to be used on large parallel computing clusters, therefore the barrier is high for widespread public use.

Ease of obtaining information and availability of technical support

The model is maintained on Github which acts as a user forum; there is no formal help desk. The Github repository does not have an active user base.

Source code availability

The model source code is open source.

Status of model development

The model is available for immediate use. The following features were recently implemented in SUNTANS: a suspended sediment transport model and a spectral wave model to include the effects of wave-driven currents and bottom stresses. The following features are under development: simulation of flows in salt-marsh estuaries with a marsh vegetation drag module along with a culvert module; and the method of subgrid bathymetry, whereby bathymetry data at a resolution that is finer than the mesh are incorporated into the solution without increasing the resolution of the underlying computational mesh.

Challenges in integration

Although the model is open source, it is designed as a research tool and is not well documented for public use. The model is highly parallelized and designed to be used on large parallel computing clusters, therefore the barrier is high for widespread public use.