FAST3D is a general-purpose three-dimensional (3D) flow model developed by Prof. Wolfgang Rodi’s group at the Institute for Hydromechanics, University of Karlsruhe, Germany. It solves the Reynolds-averaged Navier-Stokes equations with the k-ε turbulence closure using a finite volume method on non-staggered curvilinear grid (Zhu 1992). Wu et al. (2000) enhanced FAST3D to simulation of open-channel flow and sediment transport. The enhanced FAST3D model determines the free water surface level using a 2D Poisson equation derived from the 2D depth-averaged momentum equations. It computes suspended-load transport using the general convection-diffusion equation with a settling term, bed-load transport using a non-equilibrium model, and bed changes using the overall sediment mass balance equation. It uses an adaptive (moving) grid along the vertical to track the bed and water surface changes. FAST3D was validated by Wu et al. (2000) in several experimental cases, including sediment transport and bed change in an 180o channel bend. Later, FAST3D has been used successfully by Prof. Rodi’s group to simulate the 76 years’ sedimentation process near the Three Gorges Project dam (Fang and Rodi 2003) and to solve many other engineering problems. Wu and Wang (2005) and Wu (2007) further enhanced FAST3D to simulate headcut migration and local erosion around hydraulic structures, by implementing correction factors to take into account the effects of localized dynamic pressure gradient, steep bed slope, and downward flow on sediment entrainment in rapidly-varying flows.
W. Wu, W. Rodi, and T. Wenka (2000). “3-D numerical modeling of water flow and sediment transport in open channels.” J. Hydraulic Eng., ASCE, 126(1), 4–15.
H. W. Fang and W. Rodi (2003). “Three-dimensional calculations of flow and suspended sediment transport in the neighborhood of the dam for the Three Gorges Project (TGP) reservoir in the Yangtze River.” J. Hydro. Res., IAHR, 41(3), 291–307.
W. Wu and S. S.Y. Wang (2005). “Empirical-numerical analysis of headcut migration.” Int. J. Sediment Research, 20(3), 233–243.
W. Wu (2007). Computational River Dynamics, Taylor & Francis, UK, 494 p.
J. Zhu (1992). “An introduction and guide to the computer program FAST3D.” Institute for Hydromechanics, Karlsruhe University, Germany.