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2006
Hydrostatic and non-hydrostatic modeling
of internal waves (2006) - The capabilities of
both hydrostatic and non-hydrostatic internal wave models using
primitive equations are compared to
laboratory experiments. It is shown that the hydrostatic bore has
similar characteristics to the leading wave of a non-hydrostatic
train of solitary waves, which may provide a basis for subgrid-scale
internal wave closure schemes for hydrostatic models.
<web
abstract> <pdf of first page not yet available> Wadzuk, B.M., and B.R. Hodges (2006), “Hydrostatic
and non-hydrostatic modeling of internal waves,” submitted
to Journal of Engineering Mechanics, (March, 2006)
A
grid-switching strategy for computing high-frequency, high wave
number motions embedded in geophysical flows (2006) - The effects
of altering the model grid when an internal wave transitions from
linear hydrostatic behavior to nonlinear non-hydrostatic behavior
is examined.
<web
abstract> <pdf of first page not yet available> Botelho, D., J. Imberger, C. Dallimore, and B.R.
Hodges (2006), “A grid-switching strategy for computing high-frequency,
high wave number motions embedded in geophysical flows,” submitted
to International Journal for Numerical Methods in Fluids (February,
2006). Baroclinic stability of two-level semi-implicit
numerical methods for the 3D shallow water equations (2006) -
The TRIM method for baroclinic flows is shown to be unstable
in the inviscid limit for a Crank-Nicolson discretization of
the barotropic term. Theoretical stability for predictor-corrector
methods is examined.
<web
abstract> <pdf of first page not yet available>
Rueda, F.J., E. Sanmiguel-Rojas, and B.R.
Hodges (2005), “Baroclinic stability of two-level semi-implicit
numerical methods for the 3D shallow water equations,” submitted
to Journal of Computational Physics, (November, 2005).
Numerical error assessment and a temporal
horizon for internal waves in a hydrostatic model (2006) -
Methods for quantifying basin-wide numerical diffusivity and
numerical viscosity in a closed-basin stratified flow are proposed.
It is demonstrated that a hydrostatic model has a limited temporal
horizon for reasonable representation of internal wave dynamics.
<web
abstract> <pdf
of first page >
Hodges, B.R., B. Laval, and B.M. Wadzuk,
Numerical error assessment and a temporal horizon for internal
waves in a hydrostatic model,Ocean Modelling,
13(1):44-64, doi:10.1016/j.ocemod.2005.09.005
Identification of submerged large woody
debris from single-beam echo soundings (2006) -
Statistical methods for separating the LWD signal from the
background bathymetry in a river channel data set are investigated.
Scale-space analysis methods are found to be too complex and
inaccurate. A method of discrimination based on standard deviation
is proposed and is shown to be simple and effective.
<web
abstract> <pdf of first page not yet available>
White, L. , B.R.
Hodges, B. Austin, and T. Osting, (2006), "Identification
of submerged large woody debris from single-beam echo soundings,” , Journal
of Hydroinformatics, 8(1):1-12.
2005
Drifter modeling and
error assessment in wind driven currents (2005) -
A new approach is developed for modeling drifters that includes
the dynamics of forcing on the drifter body.
Prior methods of error assessment for drifter performance are
analyzed and a new "Circle Assessment" method is proposed that
provides
improved quantitative analyses.
<web
abstract> <pdf
of report (2.5 MB)>
Furnans, J.E., B.R. Hodges, and J. Imberger (2005),
Drifter Modeling and Error Assessment in Wind Driven Currents,
CRWR Online Report 05-5, Center for Research in Water Resources,
University of Texas at Austin, 172 pages, http://www.crwr.utexas.edu/online.html.
Geospatial representation of river channels
(2005) - A method of using curvilinear channel
coordinates (see Hodges & Imberger 2001, below) is adapted
into a GIS representation to provide a method of creating a smooth,
flow-oriented mesh from
bathymetry sampling or river cross-sections.
<web
abstract> <pdf
of first page>
Merwade, V.M., D.R. Maidment and B.R. Hodges,
Geospatial representation of river channels, ASCE
Journal of Hydrologic Engineering, 10(3):243-251 (2005).
Filtering the signature of submerged
large woody debris from bathymetry data (2005) - Digital
filtering methods for separating the LWD signal from the background
bathymetry in a river channel data set are investigated. Linear
filters are shown to be difficult to consistently apply. A method
using nonlinear filters is proposed. It is shown that a scaling
analysis can be used to remove the analyst's judgement from the
selection of the filter scale
<web
abstract> <pdf
of first page>
White, L., and B.R. Hodges, Filtering the
signature of submerged large woody debris from bathymetry data,
Journal of Hydrology, 309:53-65, (2005).
Grid-scale dependency of subgrid-scale structure
effects in hydraulic models of rivers and streams (2005)
- Subgrid-scale heterogeneity creates difficulties for hydraulic
modeling because the effects of turbulence propagate upscale, resulting
in turbulence models that implicitly require different calibrations
at different grid scales. We explore new approaches to addressing
this issue.
<web
abstract> <pdf
of McMat2005 conference paper (256kb)>
<pdf
of UT Graduate Student Conference paper (200kb)> <pdf
of poster (260kb)>
Fu, S. and B.R. Hodges, Grid-scale dependency
of subgrid-scale structure effects in hydraulic models of rivers
and streams, Mechanics and Materials Conference 2005 (McMat 2005),
June 1-3, 2005, Louisiana State University, Baton Rouge, Electronic
Proceedings (CD-ROM), 5 pgs.
Fu, S. and B.R. Hodges, A hybrid RANS and
LES model for studying the flow around large woody debris in a river,
University of Texas at Austin Engineering Graduate Student Research
Conference, April 28, 2005, 4 pgs.
Improved techniques for gravity current modeling
(2005) - Shallow estuaries present problems for modeling
the fate of thin layer gravity currents. This paper reflects some
of our initial work in this area.
<web
abstract> <pdf
of McMat2005 conference paper (50 kb)>
Kulis, S. and B.R. Hodges, Improved techniques
for gravity current modeling, Mechanics and Materials Conference
2005 (McMat 2005), June 1-3, 2005, Louisiana State University, Baton
Rouge, Electronic Proceedings (CD-ROM), 4 pgs.
2004
Hydrostatic and Non-hydrostatic Internal
Wave Models (2004) - An investigation of the errors
resulting from using the hydrostatic approximation in modeling internal
waves.
<web
abstract> <pdf
of report (3.2 MB)>
Wadzuk, B.M and B.R.
Hodges, Hydrostatic and Non-hydrostatic Internal Wave Models, CRWR
Online Report 04-09, Center for Research in Water Resources, University
of Texas at Austin, (2004), 77 pages, http://www.crwr.utexas.edu/online.html.
Modeling a Plunging Underflow (2004)
- This is an extension of the work Dallimore et al., 2003 (see below).
In this paper the method for coupling a 2D benthic boundary layer
model to a 3D model is extended to handle plunging underflows.
<web
abstract> <pdf
of first page>
Dallimore, C.J., J. Imberger and B.R. Hodges,
“Modeling a Plunging Underflow,” ASCE
Journal of Hydraulic Engineering, 130(11): 1068-1076, (2004).
Accuracy order of Crank-Nicolson discretization
for hydrostatic free surface flow (2004) - This
examines the use of C-N discretization in CWR-ELCOM for the free
surface, and derives a correction term that is necessary to preserve
formal second-order accuracy. Of particular interest is a demonstration
accuracy of the free surface solution for free waves is less than
second-order when the barotropic CFL is greater than unity. Some
initial results associated with this paper were presented at a conference
<more
info>. <web
abstract>. <pdf
of first page>
Hodges, B.R., “Accuracy order of Crank-Nicolson
Discretization for Hydrostatic Free Surface Flow,” ASCE
Journal of Engineering Mechanics, 130(8): 904-910 (2004).
Hodges, B.R., “A second-order correction
for semi-implicit shallow water methods,” 16th ASCE Engineering
Mechanics Conference, July 16-18 2003, University of Washington,
Seattle, Electronic Proceedings (CD-ROM ).
Numerical diffusion and dissipation
in hydrostatic models in internal waves (2004) - We
demonstrate that numerical diffusion of mass and dissipation of
energydo not monotonically decrease with grid resolution in a hydrostatic
internal wave model. Instead, changing the grid scale changes the
horizontal length scale of small waves produced through nonlinear
steepening in the absence of nonhydrostatic pressure.
<web
abstract> <pdf
of EM2004 conference paper>
Hodges, B.R., and S. K. Delavan, “Numerical
diffusion and dissipation in hydrostatic models in internal waves,”
17th ASCE Engineering Mechanics Conference, June 13-16, 2004, University
of Delaware, Newark, Electronic Proceedings (CD-ROM ), 4 pgs..
Isolation of hydrostatic regions within
a basin (2004) - This paper demonstrates how a hydrostatic
model can be used to predict regions of expected non-hydrostatic
behavior.
<web
abstract> <pdf
of EM2004 conference paper>
Wadzuk, B.M , and B.R. Hodges, “Isolation
of hydrostatic regions within a basin,” 17th ASCE Engineering
Mechanics Conference, June 13-16, 2004, University of Delaware,
Newark, Electronic Proceedings (CD-ROM ).
Lake Kinneret surface circulation with
particle tracking (2004) - Preliminary results of
model results for drifters in Lake Kinneret are presented.
<web abstract> <pdf of EM conference paper>
Furnans, J.E., B.R. Hodges and J. Imberger,
“Lake Kinneret surface circulation with particle tracking,”
17th ASCE Engineering Mechanics Conference, June 13-16, 2004, University
of Delaware, Newark, Electronic Proceedings (CD-ROM ).
2003
Coupling an underflow model to a 3D
hydrodynamic model (2003) - To solve problems of "numerical
convective entrainment" when high-density water flows under
low-density water, we develop a method to couple a 2D benthic boundary
model to 3D CWR-ELCOM. It is demonstrated with field data from Lake
Ogawara, Japan, and Lake Kinneret, Israel, that the coupled model
maintains coherent underflow characteristics that cannot be captured
by a 3D model alone.
<web
abstract> <pdf of first page>
Dallimore, C., B.R. Hodges, and J. Imberger,
"Coupling an underflow model to a 3D hydrodynamic model."
ASCE Journal of Hydraulic Engineering
129: (10): 1-10, (2003).
Reducing Numerical Diffusion Effects
with Pycnocline Filter (2003) - A methodology is proposed
to counter the cumulative effects of numerical diffusion for models
of density-stratified systems. The accumulation of even small amounts
of diffusion over a long simulation can signifcantly distort the
properties of internal waves. This journal paper is related to a
prior conference paper
<web
abstract> <pdf
of first page>
Laval, B., B.R. Hodges,
and J. Imberger, "Reducing Numerical Diffusion Effects with
Pycnocline Filter." ASCE Journal of Hydraulic Engineering
129: (3): 215-224 (2003).
Modeling Circulation in Lakes: Spatial
and Temporal Variations (2003) - The effects of spatial
and temporal variations in the wind field are examined with the
CWR-ELCOM model and field data. The mixed-layer algorithm in CWR-ELCOM
is improved with a mixing time-scale to provide temporal invariance
in results as the time step is changed.
<web
abstract> <pdf
of first page> <download
paper from L&O (420KB)>
Laval, B., J. Imberger,
B.R. Hodges, R. Stocker, “Modeling Circulation in Lakes: Spatial
and Temporal Variations,” Limnology and Oceanography,
48:(3):983-994 (2003).
Comparing hydrostatic and nonhydrostatic
Navier-Stokes models of internal waves (2003) - Preliminary
results for modeling hydrostatic and nonhydrostatic internal waves
are presented and discussed. A related paper was presented at Texas
Water 2003
<web
abstract> <pdf
of EM2003 conference paper 273 KB>
Wadzuk, B.M., and B.R. Hodges, “Comparing
hydrostatic and nonhydrostatic Navier-Stokes models of internal
waves,” 16th ASCE Engineering Mechanics Conference, July 16-18
2003, University of Washington, Seattle, Electronic Proceedings
(CD-ROM )
Wadzuk, B.M. and B.R. Hodges 2003, "The
Limitation of the Hydrostatic Approximation for Nonlinear Internal
Waves." Proceedings of Texas Water 2003, April 1-4, 2003, Corpus
Christi, TX.
A second-order correction for semi-implicit
shallow water methods (2003) - This
examines the use of C-N discretization in CWR-ELCOM for the free
surface, and derives a correction term that is necessary to preserve
formal second-order accuracy. This was the precursor to the paper
on C-N methods in 2004 (see above).
<more
info>
Hodges, B.R., “Accuracy order of Crank-Nicolson
Discretization for Hydrostatic Free Surface Flow,” ASCE
Journal of Engineering Mechanics, 130(8): 904-910 (2004).
Hodges, B.R., “A second-order correction
for semi-implicit shallow water methods,” 16th ASCE Engineering
Mechanics Conference, July 16-18 2003, University of Washington,
Seattle, Electronic Proceedings (CD-ROM ).
2002
Impacts of
Hydrological Changes on Phytoplankton Succession in the Swan River,
Western Australia (2002)- The CWR-ELCOM hydrodynamic
code is linked to the CAEDYM water quality code (also developed
at CWR) to examine the species succession in the Swan River and
how changes in the catchment during European settlement and development
may have altered the ecosystem behavior.
<web
abstract> <pdf
of first page>
Chan, T.U., D.P.
Hamilton, B.J. Robson, B.R. Hodges, and C. Dallimore. "Impacts
of hydrological change on phytoplankton succession in the Swan River,
Western Australia." Estuaries 25: 1406-1415, (2002).
2001
Simple curvilinear method for numerical
methods of open channels (2001) - A Cartesian grid
model (CWR-ELCOM) can be converted into a curvilinear model with
relatively small effort through the use of a perturbation expansion
approach - which is valid as long as the width of the system is
smaller than the large-scale radius of curvature (a typical case
for rivers and narrow reservoirs). This also allows estimation of
the scales of error for models which "straighten" the
curves in a river. Reprints are available on
request. This paper is complemented by a more detailed technical
report <more
info>. A related paper on straightening reservoir bathymetry
was also presented at a conference <more
info>.
<web
abstract> <pdf
of first page>
Hodges, B.R., and
J. Imberger. "Simple curvilinear method for numerical methods
of open channels." Journal of Hydraulic Engineering
127: (11): 949-958, (2001).
Model bathymetry for sinuous, dendritic
reservoirs (2001) - We apply the methods developed
in Hodges and Imberger (2001), above, to develop an approximate
"straightened" bathymetry that can be used for 3D reservoir
modelling.
<web
abstract> <pdf
of paper>
Waduzk, B. and B.R. Hodges, “Model bathymetry
for sinuous, dendritic reservoirs,” 6th Workshop on Physical
Processes in Natural Waters,” University of Girona, Catalonia-Spain,
27-29 June 2001, pp. 205-209 .
2000
Modeling basin-scale
internal waves in a stratified lake (2000) - The advanced
mixed-layer model algorithm used in CWR-ELCOM is described, and
the model's ability to represent the large internal wave signatures
in Lake Kinneret, Israel, is demonstrated. Direct comparisons to
extensive field data are made, with very favorable results. Reprints
are available on request.
<web
abstract> <pdf
of first page>
Hodges, B.R., J.
Imberger, A. Saggio, and K. B. Winters,"Modeling basin-scale
internal waves in a stratified lake." Limnology and Oceanography
45:(7):1603-1620, (2000).
The effects of freshwater flows and
salinity on phytoplankton biomass and composition in an urban estuary,
the Swan River, Western Australia (2000) - Preliminary
results of field and modeling studies on the Swan River are reported.
See Chan et al (2002) above for the more complete analysis.
Hamilton, D.P., T.U. Chan, B.J. Robson and
B.R. Hodges, “The effects of freshwater flows and salinity
on phytoplankton biomass and composition in an urban estuary, the
Swan River, Western Australia,” Proceedings, 3rd International
Hydrology and Water Resources Symposium, Nov. 2000, Vol 1, pp. 114-119
.
Recirculation and equilibrium displacement
of the thermocline in a wind-driven stratified lake (2000)
- Analysis of effects of vertical recirculation on the internal
wave setup due to wind forcing. It is shown that underpredicting
the depth of the surface-mixed layer in a vertically-recirculating
system can result in undepredicting the initial setup of the internal
seiche.
<web
abstract> <pdf
of paper>
Hodges, B.R. “Recirculation and equilibrium
displacement of the thermocline in a wind-driven stratified lake,”
Fifth International Symposium on Stratified Flows, Vancouver, Canada,
July 7-11, 2000, pp. 327-330 .
Numerical
diffusion in stratified lake models (2000) - Preliminary
development of a technique for ad hoc correction of numerical diffusion.
See paper Laval et al. (2003), "Reducing
Numerical Diffusion Effects with Pycnocline Filter
<web
abstract> <pdf
of paper>
Laval, B., B.R. Hodges, and J. Imberger,
“Numerical diffusion in stratified lake models,” Fifth
International Symposium on Stratified Flows, Vancouver, Canada,
July 7-11, 2000, pp. 343-348 .
Modeling the hydrodynamics of stratified
lakes (2000) - Review of principle advances in modeling.
Delivered as invited plenary lecture at Hydroinformatics 2000.
<web
abstract> <pdf
of paper>
Hodges, B.R., J. Imberger, B. Laval, J. Appt,
“Modeling the hydrodynamics of stratified lakes,” Proceedings
of Hydroinformatics 2000 (CD-ROM), Iowa Institute for Hydraulic
Research, University of Iowa, July 23-27, 2000 .
1999
and earlier
On simulation of turbulent nonlinear
free-surface flows (1999) - A moving-grid fractional-step
method in boundary-fitted curvilinear coordinates is used with dynamic
large-eddy simulation (LES) to model the turbulent flow beneath
a water wave. It is pointed out that the nonlinear kinematic boundary
condition, when filtered using LES, provides subgrid-scale correlations
that are similar to the Leonard, Cross and Reynolds terms of LES.
These terms have not been considered in any models to date. THis
work is based on my dissertation (Hodges, 1997, see top of this
page)
<web
abstract> <pdf
from journal: doi:10.1006/jcph.1998.6166 >
B.R. Hodges and R.L. Street, “On simulation
of turbulent nonlinear free-surface flows,” Journal of Computational
Physics, 151:425-457, (1999).
Wave-induced enstrophy and dissipation
in a sheared turbulent current (1998) - Taking the
results from my dissertation (Hodges, 1997; see top of this page)
a step further, we analyzed how the surface waves distort the fluctuating
enstrophy in the current.
<web
abstract> <pdf
of paper>
Hodges, B.R. and R.L. Street, Wave-induced
enstrophy and dissipation in a sheared turbulent current ,”Wave-induced
enstrophy and dissipation in a sheared turbulent current, in M.C.
Thompson and K. Hourigan (editors), Proceedings of the Thirteenth
Australasian Fluid Mechanics Conference, Monash University,
Melbourne, Australia, 13-18 Dec. 1998. Vol II, pp. 717-720.
Other conference papers that were precursors
to my dissertation:
B.R. Hodges and R.L. Street, “Three-dimensional,
nonlinear, viscous wave interactions in a sloshing tank,”
in Proceedings of the Fluids Engineering Summer Meeting, Vol. 3,
FED-Vol. 238, ASME, pp. 361-367, (1996).
B.R. Hodges, R.L. Street and Y. Zang, “A
method for simulation of viscous, nonlinear, free-surface flows,”
in Twentieth Symposium on Naval Hydrodynamics, National Academy
Press, pp. 791-809, (1996).
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