Solvers

TUFLOW Classic has 1D and 2D CPU based solvers. The 2D solver is a proven, industry established, implicit 2nd order spatial finite difference solution of the full 2D hydrodynamic equations, while the 1D solver is an explicit 2nd order solution of the full 1D equations. Both solvers include the handling of upstream controlled flow regimes such as weir and supercritical flows, and can be easily linked.

The TUFLOW Classic solvers are one of the world’s most successfully applied with extensive use to a wide range of applications for over 25 years. During the last 15 years, numerous enhancements have been made to fine-tune the performance of both 1D and 2D solutions, especially for modelling the more complex flows associated with flooding and for urban drainage. The 1D/2D dynamic linking capabilities are also tried and proven through 25 years of continual application and enhancement, and lead the way in seamless 1D/2D dynamically linked models.

TUFLOW’s GPU Module is a powerful new 2D solver that value adds to the TUFLOW “Classic” product. As its name implies it utilises the substantial parallel computing ability of NVidia Graphics Processor Units, or GPUs. The new GPU solver was developed so that it was efficiently parallelised with maximum speed as the implicit TUFLOW Classic solver is not optimal for maximum speed parallelisation due to dependencies within some of its logical loops.

The 2D solver is an explicit solution of the full 2D Shallow Water Equations, including sub-grid scale eddy viscosity. The scheme is volume and momentum conserving, is 1st order spatially and 4th order in time (1st and 2nd order in time are also available but not recommended). Adaptive (conditionally stable) or fixed time-stepping options are available. The solver has been designed for high-speed solutions of complex 2D flow behaviour. A 2nd order spatial solution is planned for a future update, and dynamic links with TUFLOW Classic’s 1D solver are currently under development.

The power of modern GPUs combined with the super fast TUFLOW GPU solver allows very large models (>100 million cells) with fine grids to be simulated within a practical timeframe. The adaptive time-stepping guarantees that the model remains stable. The solver can operate over multiple GPU cards.

The Green-Ampt, Horton and IL/CL infiltration algorithms are incorporated, Manning’s n can be varied with depth, and spatially and temporally varying rainfall grids can be utilised, so GPU is well-suited to modelling direct rainfall applications.

The GPU solver is built inside TUFLOW Classic, therefore the powerful pre and post-processing capabilties that make TUFLOW hydraulic modelling highly work flow efficient are available.

TUFLOW GPU was submitted for the 2012 UK Environment Agency 2D Benchmark Tests, where along with TUFLOW and TUFLOW FV, were top performers in terms of consistent results and run times. The scheme has also been benchmarked against theoretical solutions and through comparisons with other hydraulic solvers.

TUFLOW GPU in its present form is ideally suited to:

  • first-pass or broad-scale regional rapid hydraulic solutions;
  • as an alternative to using hydrologic models (ie. whole of catchment modelling);
  • real-time flood inundation forecasting; and
  • high resolution 2D solutions.

TUFLOW Classic’s 1D pipe/pit/manhole functionality is presently being incorporated for future versions. The first phase of this development has been completed allowing the ability to simulate depth-discharge type pits. This feature, called Virtual Pipes, is available in the 2016-03 TUFLOW release. Testing has commenced on full pipe network functionality in TUFLOW GPU with the aim of incorporating it in the 2017 TUFLOW release.