FASTER2D
FASTER2D is a depth-averaged two-dimensional (2D) model for Flow And Sediment Transport in Estuaries and Rivers. It is based on the general-purpose FAST2D (Flow Analysis and Simulation Tool) model developed by Prof. Wolfgang Rodi’s group at the Institute for Hydromechanics, University of Karlsruhe, Germany. FAST2D solves the Reynolds-averaged Navier-Stokes equations using a finite volume method on non-staggered curvilinear grid, which adopts the SIMPLE(C) algorithms with Rhie and Chow’s momentum interpolation technique for the coupling of velocity and pressure (Zhu 1992). FASTER2D applies the numerical algorithms of FAST2D to solve the depth-averaged shallow water flows (Wu 2004). FASTER2D adopts a non-equilibrium approach for nonuniform total-load sediment transport. The model calculates bed load and suspended load separately or jointly according to sediment transport mode. It calculates flow and sediment transport in a decoupled manner, but adopts a coupling procedure for the calculations of sediment transport, bed change and bed material sorting.
FASTER2D has the following special features:
- The eddy viscosity is determined using five depth-averaged 2D turbulence closures, including the depth-averaged parabolic eddy viscosity model, modified mixing length model, standard k-ε, non-equilibrium k-ε and re-normalized group (RNG) k-ε turbulence model (Wu et al. 2004).
- The vegetation effects are taken into account by including the drag force exerted by the flow on vegetation in the momentum equations, and the generation and dissipation of turbulent energy due to the presence of vegetation in the k and ε equations (Wu et al. 2005).
- The sediment transport capacity is determined using four formulas, which are capable of accounting for the hiding and exposure effects among different size classes.
- The time lag between water and sediment transport is considered, in which the depth-averaged suspended-sediment velocity and the bed-load velocity are smaller than the depth-averaged flow velocity (Wu et al. 2006).
- The effects of helical flow on main flow and sediment transport in curved channels are considered by including dispersion terms in the depth-averaged 2-D momentum equations and suspended-load transport equation, as well as modifying the bed-load transport angle (Wu and Wang 2004a).
- The effects of the gravity on the sediment transport capacity and the bed-load movement direction in channels with steep slopes are considered (Wu 2004).
- The model is enhanced to simulate the local scour around hydraulic structures after modifying Wu et al.’s (2000) sediment transport capacity formulas to account for the influences of pressure gradient and turbulence intensity on sediment movement (Wu and Wang 2002).
- The model can simulate tide flow, salinity and cohesive sediment transport in estuaries, taking into account the influence of sediment size, sediment concentration, salinity and turbulence intensity on the flocculation of cohesive sediment (Wu and Wang 2004b).
References:
W. Wu (2004). “Depth-averaged 2-D numerical modeling of unsteady flow and nonuniform sediment transport in open channels,” J. Hydraulic Eng., ASCE, 130(10), 1013–1024.
W. Wu and S.S.Y. Wang (2004a). “Depth-averaged 2-D calculation of flow and sediment transport in curved channels,” Int. J. Sediment Research, 19(4), 241–257.
W. Wu and S.S.Y. Wang (2004b). “Depth-averaged 2-D calculation of tidal flow, salinity and cohesive sediment transport in estuaries,” Int. J. Sediment Research, 19(3), 172–190.
W. Wu, P. Wang, and N. Chiba (2004). “Comparison of five depth-averaged 2-D turbulence models for river flows,” Archives of Hydro-Engineering and Environmental Mechanics, Polish Academy of Science, 51(2), 183–200.
W. Wu, F.D. Shields, Jr., S.J. Bennett, and S.S.Y. Wang (2005). “A depth-averaged 2-D model for flow, sediment transport and bed topography in curved channels with riparian vegetation,” Water Resources Research, AGU, 41(W03015), p. 15.
W. Wu, M. Altinakar, and S.S.Y. Wang (2006). “Depth-average analysis of hysteresis between flow and sediment transport under unsteady conditions,” Int. J. Sediment Research, 21(2), 101–112.
W. Wu and S.S.Y. Wang (2002). “Prediction of local scour of non-cohesive sediment around bridge piers using FVM-based CCHE2D model,” Proc. First International Conference on Scour of Foundations, Texas A&M University, Nov. 17-20. (on CD Rom)
W. Wu, S.S.Y. Wang, and Y. Jia (2000). “Nonuniform sediment transport in alluvial rivers,” J. Hydraulic Research, IAHR, 38(6), 427–434.
J. Zhu (1992). “FAST2D: A computer program for numerical simulation of two-dimensional incompressible flows with complex boundaries.” Institute for Hydromechanics, Karlsruhe University, Germany.