HPC Introduction: Difference between revisions
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=Introduction=
TUFLOW HPC is now industry standard. While TUFLOW Classic is still supported, it is recommended to use TUFLOW HPC.
TUFLOW Classic is limited to running a simulation on a single CPU core, whereas HPC provides parallelisation of the TUFLOW model allowing modellers to run a single TUFLOW model across multiple CPU cores or GPU graphics cards (which utilise thousands of smaller CUDA* cores). Simulations using GPU hardware has shown to provide significantly quicker model run times for TUFLOW users.<br>
In general, most of the functionality and features of TUFLOW Classic are available in HPC. Additionally, HPC offers several advanced features not supported in Classic, including:
* Quadtree and sub-grid sampling
* High resolution map output grids
* Groundwater infiltration and sub-surface flows
* Wu turbulence formulation
* TMR bridge inputs (2d_bg) and simulation methods
===Solution Scheme, Cell Discretisation and Parallelisation===
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* Represent where the momentum equation terms are centred and where upstream controlled flow regimes are applied;
* Deactivate if the cell has dried (based on the ZC point) and cannot flow; and
* Wet and dry independently of the cell wetting or drying (see Cell Wet/Dry Depth). This allows for the modelling of “thin” obstructions such as fences and thin embankments relative to the cell size (
ZH points:
* Play no role hydraulically. This point location is used for output processing;
* The only elevations written to the
Within the above sub-grid framework, using TUFLOW HPC time derivatives of cell averaged water depth, u-velocity and v-velocity are computed on a cell-by-cell basis and the model evolved using an explicit ODE solver. Calculation of the cell based derivatives are highly independent of each other making it possible to run this solution scheme across multiple processors or GPU cards. Parallelisation is done by breaking up the model into vertical ribbons. Each ribbon of the model is run on a different processor (or GPU card) with boundary information shared between processors at each timestep.<br>
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===Benefits of HPC===
So what does this mean for modellers? <br><br>
* Monte Carlo design assessments
* Rainfall ensemble design assessments
* High resolution 1D underground / 2D above ground integrated urban drainage
* High resolution floodplain lumped hydrology / hydraulic modelling (either fully 2D or including nested 1D open channels and pipes)
* Whole of catchment direct rainfall
* Flood forecast modelling
* Long-term water resource management modelling
The unconditional stability and higher order accuracy of TUFLOW HPC also lends itself well to highly transient situations, such as dam break assessments, where other solvers would either become unstable, lose accuracy or experience impractical simulation slow-down due to the need to solve at an extremely small timestep.<br>
▲So what does this mean for modellers? By providing the ability to run models on Graphics Cards, we can achieve significantly shorter model run times, increasing our modelling capabilities to be able to run continuous hydraulic models, with higher cell resolution, across larger extents and more scenarios (Monte Carlo, rainfall ensembles, high resolution 1D underground / 2D above ground urban, etc.).<br>
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