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Akuna Architecture and Toolset Components

Akuna Architecture and Toolset Components


Akuna is a collection of integrated toolsets that are accessed through a personal computer. However, to access toolset functionality, the user logins into the Velo server. Hence, Akuna primarily functions as a user interface to the toolsets (Figure 1).

Collaboration, extensibility and scalability are attributes that have driven Akuna's design. Instead of building a simulator-specific application for a single user, architectural mechanisms have been incorporated to create an application that allows a community of scientists to jointly develop and run simulations, seamlessly discover and share results, and easily extend the core of Akuna to support any simulator. It is designed to be simulator agnostic with well-defined extension points for supporting new simulators.

Figure 1. Akuna Architecture.

(Top Circle)

  • User interface to several toolsets, including model setup, data management, simulation and visualization toolsets  
  • Akuna is built around the Velo core, which provides the collaboration component to Akuna, and the connection to the computer where users launch simulations

(Box at Left)

  • Velo capabilities are listed separately to indicate that users execute Akuna on their personal computer, but perform operations on a remote computer

(Bottom Circle)

  • The simulation controller (Agni) launches jobs, performs analyses, and communicates results back to the user through Velo. 
  • Akuna can be linked to different simulation codes.  Although Akuna it has been designed to interface with Amanzi, it can be linked to other codes



The Akuna user platform is built on the Velo framework (Gorton et al, 2012) which provides a rich client environment for managing projects and conducting and analyzing simulations, a server for data sharing, annotation, simulation execution, and communication, and a Tool Integration Framework (TIF) for connecting any type of software application into the Velo front or back end. Velo’s TIF includes embeddable APIs that provide a foundation for integrated desktop and high performance computing (HPC) activities. As part of the TIF, Velo employs declarative extension mechanisms that Akuna leverages for tool registration and job execution. Figure 1 illustrates the areas where Akuna has extended the Velo framework.

The Akuna-Velo framework provides a client-server architecture.  This means that Akuna is installed locally on a user’s desktop computer, and users log into a server to access the Velo framework and launch toolsets within Akuna. All project data are stored on the server and protected with fine-grained access controls. The user environment allows users to create groups and control permissions on their projects, enabling them to work in private workspaces or to enable collaborative modeling as appropriate. Velo's messaging system allows users to see changes made by others in real time.


An important component of the Akuna framework is the use of Agni, the simulation controller and analysis tool. Through Akuna, Agni provides toolkits for parameter estimation (PE), uncertainty quantification (UQ), and sensitivity analysis (SA). It also provides simulation execution control for the simulation ensembles and the single run (SR), risk assessment (RA) and decision support (DS) toolsets. Agni also accepts job launching requests from the Akuna client, executes them and reports information back to the UI. Agni controls the execution of the simulator on the compute server. Agni is also designed to be simulator agnostic for supporting any simulator.


GRIDDER is a simple, interactive grid generation tool for creating orthogonal, 2D quadrilateral or 3D hexahedral grids. Grid spacing can be even, logarithmic, or geometric. Gridder is used in the Model Setup Toolset for generating orthogonal grids (


LaGriT is a library of user callable tools that provide mesh generation and optimization in two and three dimensions. LaGrit is used in the Model Setup Toolset for generating unstructured grids using the Exodus file format supported by Amanzi ( .



VisIt is a distributed, parallel visualization and graphical analysis tool for data defined on two- and three-dimensional (2D and 3D) meshes. Users can quickly generate visualizations, animate them through time, manipulate them with a variety of operators and mathematical expressions, and save the resulting images and animations for presentations . VisIt contains a rich set of visualization features to enable users to view a wide variety of data including scalar and vector fields defined on two- and three-dimensional (2D and 3D) structured, adaptive and unstructured meshes. VisIt is used in Akuna to visualize simulation results through the VisIt Perspective (



The Akuna Visualization Toolset is designed to plot results from multiple simulation runs so that users can quickly analyze results for ensemble simulations. Both simulated and observed data is available for 2D plotting, which is largely focused on observation points that the user has defined within the simulation domain. AkunaViz takes advantage of JFreeChart, an open source Java chart library that supports a wide range of chart types, including line plots, scatter plots and histograms.


Data Management

Akuna also has developed access to a remote Data Management Toolset to import, organize, retrieve, and search across various types of observational datasets needed for environmental site characterization and numerical modeling. The framework provides capabilities to organize, interactively browse on maps, search by filters, select desired data, plot graphs, and save selected data for subsequent use in the modeling process. Users access the database through the simulation toolsets, where measurement data is used in the analysis (


Risk Assessment

The Risk Assessment Toolset was developed from a component of the PHOENIX GIS Software base and provides calculations of dose and risk from simulations that have been executed within the Akuna workflow. The RA Toolset provides data, tools, and guidance to enhance the integration of risk in an environmental regulatory decision process. The Toolset provides user support to facilitate analyses of impacts from current and future exposure to contaminants of concern to human health and ecological endpoints.


Decision Support

The Decision Support Toolset is a component of the MADS (Model Analysis and Decision Support) software, which provides users with a computational framework for scientifically defensible decision making. Specifically, the initial implementation of this toolset focuses on providing guidance for optimizing monitoring well locations. To this end, tools are provided for defining monitoring objectives and performance metrics, as well as for evaluating contaminant plumes and their uncertainties (