My interest in computational fluid dynamics
(CFD) models has been motivated by three factors:
To date, I have primarily used a two-dimensional (2D) code called
FESWMS and marketed by BOSS as SMS (Surface
Water Modelling System
). In general, with good topographic boundary
conditions we can produce very reasonable simulations over short temporal
scales and over small reach scales (e.g. figure at right). CFD modelling
is very time consuming and computationally demanding, but is very
helpful for gaining insight into research questions at sub-reach scales.
However, 2D and 3D CFD models of meaningful spatial resolutions are
impractical at catchment scales or over longer time-scales. Furthermore,
with a few notable exceptions (CFD codes with sediment transport capability
for sand-bedded rivers), most CFD codes are impractical to run with
a dynamic bed boundary condition. These limitations have led me to
explore a reduced-complexity class of models (cellular automaton).
Example CFD Simulation. A) Portion of
a 2D CFD simulation of flow around and over boulder complexes in a
spawning habitat enhancement site on the lower Mokelumne River. The
intensity of blue is scaled to the water depth solution (dark blue
is deep); the arrows represent depth-averaged flow directions with
the color scaling to the velocity magnitude (red is slow, green and
blue are fast). Notice the boulder complex in the upper right where
the model effectively captures flow around the boulder, and the hydraulic
jump over the submerged boulder complex. B) A photograph of the boulder
complex in the upper right of figure A at the same flow as the simulation
(approx 6 cumecs) ©2002 Wheaton (See Photo Copyright
Publications using CFD Tools
- MacWilliams, M. L. Jr.,
Wheaton, J.M., Pasternack, G.B., Street, R. L. and Kitanidis,
P. K. , 2006.
Flow convergence and routing hypothesis for pool-riffle maintenance
in alluvial rivers, Water Resources Research, 42, W10427.
- Pasternack, G.B., Gilbert,
A.T., Wheaton, J.M. and Buckland, E.M., (In Press). Error
Propagation for Velocity and Shear Stress Prediction: Using 2D
Models For Environmental Management. Journal of Hydrology.
- Wheaton, J. M., Pasternack,
G. B., & Merz, J. E. 2004. Spawning
Habitat Rehabilitation - II. Using Hypothesis Testing and Development
in Design, Mokelumne River, California, U.S.A., International
Journal of River Basin Management, 2(1): 21-37.