Breaking the gridlock

Posted on December 9, 2010


Conventional  mathematical  models of river and floodplain flows employ reference grids that are fixed in space.  While convenient in some respects, this approach has drawbacks – for example, tracking expanding flows over dry river beds using fixed grids is a complicated matter, and inserting new grids to increase the spatial resolution is computationally awkward.   These problems can be circumvented by using moving-grid (Lagrangian) models, in which parcels of water retain their identity as they move, and where the equations of motion describe fluid particles, not fluid volumes.  The use of moving-grid models also avoids the introduction of truncation errors caused by the need to convert from different types of equation systems (differential to discrete).  Australian researchers have developed a moving-grid model capable of describing flows in rivers and their associated floodplains.   The model was calibrated with 1995 flood data from the upper reaches of theGascoyneRiver, and validated with 1999 flood data.  Output from the model gave good agreement with data on the flood hydrograph (changes in flow depth with time) in the river, and accurately reproduced patterns of wave propagation observed in flume experiments.  

Reference:  Devkota, B.H. & Imberger, J.  2009.  Lagrangian modeling of the dynamics of river and floodplain flow.  Journal of Hydraulic Engineering 135, 771-782.

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Posted in: water flow