2.2 Simulation Tiers

A TUFLOW FV simulation is comprised of three simulation tiers as illustrated in Figure 2.1. Each TUFLOW FV simulation comprises:

• Tier 1 — Simulation class: A user defined simulation class instance (Section 2.2.1)
• Tier 2 — Model classes: A suite of model class instances associated with the simulation class (Section 2.2.2)
• Tier 3 — Model implementations: A selected implementation for each model class instance (Section 2.2.3)

Figure 2.1: TUFLOW FV model architecture tiers

2.2.1 Tier 1: Simulation Class

A simulation class defines the type of TUFLOW FV model being constructed and the modelling objective it is intended to address. It determines which physical and numerical processes are active in the simulation and, by extension, which model components must be configured. The available simulation classes and their typical applications are summarised in Table 2.1, which can be used to identify the appropriate simulation class for a given modelling problem.

Table 2.1: TUFLOW FV simulation class instances

Simulation Class Instance	Potential Uses
Two Dimensional Hydrodynamics (2D HD)	Simulation of 2D hydrodynamic use cases such as: \(\cdot\quad\)Storm tide or tsunami impact assessment \(\cdot\quad\)Astronomical tide modelling \(\cdot\quad\)Flooding and floodplain management
Three Dimensional Hydrodynamics (3D HD)	Simulation of 3D hydrodynamic use cases which do not require the simulation of salinity, temperature and density effects such as: \(\cdot\quad\)Rudimentary scour assessment \(\cdot\quad\)Hydraulic structure design \(\cdot\quad\)Flooding and floodplain management
Advection Dispersion (AD)	Simulation in 2D or 3D with salinity, temperature and/or non-transformative tracers for use cases such as: \(\cdot\quad\)Coastal and estuarine assessments \(\cdot\quad\)Lake hydrodynamics \(\cdot\quad\)Rudimentary tracer assessments
Sediment Transport (ST)	Simulation of coastal, estuarine, riverine, lake and catchment sediment transport processes for use cases such as: \(\cdot\quad\)Dredging and navigation management \(\cdot\quad\)Scour assessments \(\cdot\quad\)Channel design \(\cdot\quad\)Environmental impact assessment
Water Quality (WQ)	Simulation of coastal, estuarine, riverine, lake and catchment transformative water quality processes for use cases such as: \(\cdot\quad\)Disolved oxygen, inorganics and organic matter dynamics \(\cdot\quad\)Outfall impact assessment \(\cdot\quad\)Water supply and bathing waters \(\cdot\quad\)Aquaculture operations
Particle Tracking (PT)	Discrete particle tracking for use cases such as: \(\cdot\quad\)Environmental impact assessments \(\cdot\quad\)Rescue and salvage \(\cdot\quad\)Animal migration \(\cdot\quad\)Aquaculture operations

Simulation classes are cumulative: more advanced classes extend the capability of simpler classes, with the 2D Hydrodynamic (2D HD) simulation class providing the foundation for all other simulation classes. The dependency relationships between simulation classes are summarised in Table 2.2. Each simulation class has a corresponding model construction chapter.

Table 2.2: TUFLOW FV simulation class dependencies

Simulation Class Instance	Simulation Class Dependencies
2D HD	Not applicable - 2D HD is the fundamental simulation class
3D HD	2D HD
AD	2D HD or 3D HD
ST	AD
WQ	AD or ST
PT	Can be run on any of the above simulation classes

2.2.2 Tier 2: Model Class

Each simulation class (Tier 1) is associated with a defined suite of model classes (Tier 2). For a given simulation class, individual model classes may be either required, conditionally required, or optional, and this status is identified consistently throughout the model construction chapters. As simulation classes build on one another, the underlying model class suites expand, with model classes introduced in earlier simulation classes reused or extended in later classes.

Model classes represent discrete physical or numerical components of a simulation and form the primary organisational units of the model construction chapters. The model class suites associated with each simulation class are summarised in Table 2.3 and illustrated in Figure 2.2.

Table 2.3: TUFLOW FV simulation class instances and corresponding model class suites

Simulation Class Instance	Model Class Suite
2D HD	\(\cdot\quad\) Coordinate Reference Frame \(\cdot\quad\) Hardware (optional) \(\cdot\quad\) Spatial Order (optional) \(\cdot\quad\) Simulation Time Settings \(\cdot\quad\) Computational Timestep \(\cdot\quad\) Wetting And Drying (optional) \(\cdot\quad\) Bottom Drag \(\cdot\quad\) Horizontal Mixing \(\cdot\quad\) Wind Stress (optional) \(\cdot\quad\) Computational Mesh \(\cdot\quad\) Bathymetry \(\cdot\quad\) Materials \(\cdot\quad\) Initial Conditions (optional) \(\cdot\quad\) Boundary Conditions \(\cdot\quad\) Hydraulic Structures (optional) \(\cdot\quad\) Model Output
3D HD	2D HD Simulation Class plus \(\cdot\quad\) Vertical Mixing
AD	2D HD or 3D HD Simulation Class plus \(\cdot\quad\) Salinity (optional) \(\cdot\quad\) Temperature (optional) \(\cdot\quad\) Tracer (optional) \(\cdot\quad\) Atmospheric Heat Exchange (optional)
ST	AD Simulation Class plus \(\cdot\quad\) Sediment \(\cdot\quad\) Sediment Configuration
WQ	AD or ST Simulation Class plus \(\cdot\quad\) Water Quality \(\cdot\quad\) Water Quality Configuration
PT	Any of the above simulation classes plus \(\cdot\quad\) Particle Tracking Configuration

Figure 2.2: TUFLOW FV simulation class and model class instance

2.2.3 Tier 3: Model Implementations

Model implementations (Tier 3) configure a model class (Tier 2). Each model class can select only one model implementation. Available model implementations are summarised in Table 2.4.

Table 2.4: TUFLOW FV model classes and available model implementations

Model Class	Model Implementation
Coordinate Reference Frame	\(\cdot\quad\)Cartesian (Metric Units) \(\cdot\quad\)Cartesian (US Customary Units) \(\cdot\quad\)Spherical (Metric Units)
Spatial Order (optional)	\(\cdot\quad\)First Order \(\cdot\quad\)Second Order
Hardware (optional)	\(\cdot\quad\)CPU \(\cdot\quad\)GPU
Simulation Time Settings	\(\cdot\quad\)Hours \(\cdot\quad\)ISODate
Computational Timestep	\(\cdot\quad\)Computational Timestep
Wetting And Drying (optional)	\(\cdot\quad\)Wetting And Drying
Bottom Drag	\(\cdot\quad\)Manning \(\cdot\quad\)ks \(\cdot\quad\)ks (sediment coupled)
Horizontal Mixing	\(\cdot\quad\)None \(\cdot\quad\)Constant \(\cdot\quad\)Smagorinsky \(\cdot\quad\)Wu \(\cdot\quad\)Elder \(\cdot\quad\)Warmup
Wind Stress (optional)	\(\cdot\quad\)Wu \(\cdot\quad\)Constant \(\cdot\quad\)Kondo
Computational Mesh	\(\cdot\quad\)Unstructured \(\cdot\quad\)Structured
Bathymetry	\(\cdot\quad\)Static (potentially multiple) \(\cdot\quad\)Time Varying (potentially multiple)
Materials	\(\cdot\quad\)Spatially Constant \(\cdot\quad\)Spatially Varying (potentially multiple)
Initial Conditions (optional)	\(\cdot\quad\)Spatially Constant \(\cdot\quad\)Spatially Varying (potentially multiple) \(\cdot\quad\)Ocean Circulation Model \(\cdot\quad\)Restart File
Boundary Conditions	\(\cdot\quad\)Water Level (potentially multiple) \(\cdot\quad\)Inflow/Outflow (potentially multiple) \(\cdot\quad\)Stage Discharge (potentially multiple) \(\cdot\quad\)Ocean Circulation Model (potentially multiple) \(\cdot\quad\)Atmospheric (potentially multiple) \(\cdot\quad\)Spectral Wave (potentially multiple) \(\cdot\quad\)Mass (potentially multiple) \(\cdot\quad\)Force (potentially multiple) \(\cdot\quad\)Zero Gradient and Reflective (potentially multiple) \(\cdot\quad\)Transport File
Hydraulic Structures	\(\cdot\quad\)Weir (potentially multiple) \(\cdot\quad\)Culvert (potentially multiple) \(\cdot\quad\)Bridge (potentially multiple) \(\cdot\quad\)Porous (potentially multiple) \(\cdot\quad\)User-Defined Matrix (potentially multiple) \(\cdot\quad\)User-Defined Timeseries (potentially multiple) \(\cdot\quad\)Wall (potentially multiple) \(\cdot\quad\)Bubble Plume (potentially multiple) \(\cdot\quad\)Operational Control (optional, potentially multiple)
Model Output	\(\cdot\quad\)Log Files And Diagnostics \(\cdot\quad\)Check Files (potentially multiple) \(\cdot\quad\)Point (potentially multiple) \(\cdot\quad\)Line (potentially multiple) \(\cdot\quad\)Mesh (potentially multiple) \(\cdot\quad\)Hydraulic Structure (potentially multiple) \(\cdot\quad\)Mass Balance \(\cdot\quad\)Restart File \(\cdot\quad\)Transport File
Vertical Mixing	\(\cdot\quad\)None \(\cdot\quad\)Constant \(\cdot\quad\)Parametric \(\cdot\quad\)K-Epsilon \(\cdot\quad\)K-Omega
Salinity (optional)	\(\cdot\quad\)None \(\cdot\quad\)Barotropic \(\cdot\quad\)Baroclinic
Temperature (optional)	\(\cdot\quad\)None \(\cdot\quad\)Barotropic \(\cdot\quad\)Baroclinic
Tracer (optional)	\(\cdot\quad\)None \(\cdot\quad\)Conservative \(\cdot\quad\)Decay \(\cdot\quad\)Settling
Atmospheric Heat Exchange (optional)	\(\cdot\quad\)On \(\cdot\quad\)Off
Sediment	\(\cdot\quad\)None \(\cdot\quad\)Barotropic \(\cdot\quad\)Baroclinic
Sediment Configuration	\(\cdot\quad\)Sediment Control File
Water Quality	\(\cdot\quad\)None \(\cdot\quad\)TUFLOW
Water Quality Configuration	\(\cdot\quad\)Water Quality Control File
Particle Tracking Configuration	\(\cdot\quad\)None \(\cdot\quad\)Particle Tracking Control File