Basic information about CWR-ELCOM (Technical manuals)

Numerical Techniques in CWR-ELCOM - a technical report outlining the detailed numerical implementaton of the model. Citation: Hodges, Ben. R. (2000). Numerical techniques in CWR-ELCOM. Centre for Water Research, University of Western Australia. Technical Report WP 1422-BH, 37 pgs. <web abstract> <download pdf (300 KB)>

CWR-ELCOM User Guide - a brief outline of the basic concepts of operating CWR-ELCOM. Since the code is a resesarch tool and is continually undergoing revision, the user guide is generally out of date. Citation: Laval, Bernard, and Ben R. Hodges (2000). The CWR Estuary and Lake Computer Model ELCOM User Guide. Centre for Water Research, University of Western Australia. Technical Report, 67pgs. <web abstract> <download pdf (400 KB)>

Heat budget and thermodynamics at a free surface - a review of the state-of-the-science in modeling surface heat transfer and the techniques used in CWR-ELCOM. Citation: Hodges, Ben. R. (2000). Heat budget and thermodynamics at a free surface. Centre for Water Research, The University of Western Australia. Technical Report ED 1300 BH, 14 pgs. <web abstract> <download pdf (370 KB)>

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. Citation: 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). <web abstract> <pdf of first page>

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>. Citation: Hodges, B.R., and J. Imberger. "Simple curvilinear method for numerical methods of open channels." Journal of Hydraulic Engineering 127: (11): 949-958, (2001). <web abstract> <pdf of first page>

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. Citation: 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). <web abstract> <pdf of first page>

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. Citation: 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). <web abstract> <pdf of first page> <download paper from L&O (420KB)>

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 <more info> Citation: Laval, B., B.R. Hodges, and J. Imberger, "Reducing Numerical Diffusion Effects with Pycnocline Filter." Journal of Hydraulic Engineering 129: (3): 215-224 (2003). <web abstract> <pdf of first page>

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. Citation: Dallimore, C., B.R. Hodges, and J. Imberger, "Coupling an underflow model to a 3D hydrodynamic model." Journal of Hydraulic Engineering 129: (10): 748-757, (2003). <web abstract> <pdf of first page>

Modeling a Plunging Underflow (2004) - This is an extension of the work Dallimore et al., 2003 (see above). In this paper the method for coupling a 2D benthic boundary layer model to a 3D model is extended to handle plunging underflows. Citation: Dallimore, C.J., J. Imberger and B.R. Hodges, “Modeling a Plunging Underflow,” ASCE Journal of Hydraulic Engineering, 130(11): 1068-1076, (2004). <web abstract> <pdf of first page>

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>. The complete paper on this topic will appear in the August 2004 issue of Journal of Engineering Mechanics. Citation: .Hodges, B.R., “Accuracy order of Crank-Nicolson Discretization for Hydrostatic Free Surface Flow,” ASCE Journal of Engineering Mechanics, 130(8): 904-910 (2004). <web abstract> <pdf of first page>

Hydrostatic and Non-hydrostatic Internal Wave Models (2004) - A non-hydrostatic solver is added to ELCOM (in 2D x-z) and the results for hydrostatic and non-hydrostatic internal wave solutions are compared to the lab experiments of Horn et al (J. Fluid Mech. 2001) This technical report is the final report for ONR Young Investigator Program Award Contract N00014-01-1-0574, and is substantially the dissertation submitted by Dr. Bridget Wadzuk for her PhD. Citation: 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. <web abstract> <download report (3.2 MB PDF)>

Numerical error assessment and a temporal horizon for internal waves in a hydrostatic model (2005) - 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. Citation: 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. <web abstract> <pdf of first page>

Baroclinic stability of two-level semi-implicit numerical methods for the 3D shallow water equations (2005) - 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. Citation: 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). <web abstract> <pdf of first page not yet available>

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. Citation: 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).<web abstract> <pdf of first page not yet available>

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. Citation: Wadzuk, B.M., and B.R. Hodges (2006), “Hydrostatic and non-hydrostatic modeling of internal waves,” submitted to Journal of Engineering Mechanics, (March, 2006). <web abstract> <pdf of first page not yet available>