Abstract
A fully Lagrangian method is presented for the accurate simulation of advectiondiffusion transport in both steady and unsteady open channel flows. Numerical results arepresented for Gaussian tracer distributions, top hat tracer distributions, and steep tracerfronts (step function) profiles in a uniform flow and are compared against analyticalsolutions and against the results obtained with an Eulerian Quadratic UpstreamInterpolation for Convective Kinematics with Estimated Streaming Terms (QUICKEST)method. It is demonstrated that the Lagrangian scheme can totally eliminate numericaldiffusion and oscillations including those normally observed in steep frontal regions in mostEulerian schemes. In steady, uniform flow, the scheme allowed a large time step to beused and provides exact solutions for a wide range of Courant numbers (results are presentedfor Cr from 0 to 20) and for an entire range of grid Peclet numbers (from 0 to infinity). Thesesimulation results for a uniform flow were extended to flows due to simple waves,solitary waves, and undular bores; again, the scheme produced excellent results. It is shownthat the simple Lagrangian model is an efficient and accurate tool to predict transport inadvection dominated systems, and when it is coupled with the new Lagrangian river model,the dynamic river model, it can be an ideal model for long-term and large-scale simulation oftransport for water quality in river systems and for transport with steep frontal regions
Original language | English |
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Pages (from-to) | Article number W12406, 14pp |
Journal | Water Resources Research |
Volume | 45 |
Issue number | W12406 |
DOIs | |
Publication status | Published - 2009 |