THE SWAM'99 WORKSHOP — AN OVERVIEW

2001 ◽  
Vol 09 (01) ◽  
pp. 1-16 ◽  
Author(s):  
A. TOLSTOY ◽  
K. SMITH ◽  
N. MALTSEV
Keyword(s):  
Shallow Water ◽  
Transmission Loss ◽  
Acoustic Modeling ◽  
Test Cases ◽  
Special Issue ◽  
Propagation Modeling

The SWAM'99 (Shallow Water Acoustic Modeling, 1999) workshop on the topic of benchmarking shallow water range-dependent propagation modeling was held in Monterey CA in September No specific benchmarks were generated. Rather, each participant offered his (her) Transmission Loss curves for comparison with other results. This overview article will: • discuss the six (6) test cases; • discuss each individual's contribution to this benchmarking effort (see the associated articles in this Special issue for full details); • conclude with suggestions for future efforts.

MULTIPLICATIVE PADÉ PE FORMULATION APPLIED TO SWAM'99 TEST CASES

2001 ◽  
Vol 09 (01) ◽  
pp. 227-241 ◽  
Author(s):  
WOOJAE SEONG ◽  
BYUNGHO CHOI
Keyword(s):  
Parabolic Equation ◽  
Shallow Water ◽  
Environmental Changes ◽  
Near Field ◽  
Acoustic Propagation ◽  
Acoustic Modeling ◽  
Test Cases ◽  
Underwater Sound ◽  
Depth Direction ◽  
National University

Accurate forward modeling of acoustic propagation is crucial in underwater sound applications that rely on coherent field predictions, such as source localization and geoacoustic inversion based on matched field processing concepts. As acoustic propagation in shallow water environments becomes important in recent years, range-dependent modeling due to environmental changes has to be considered of which parabolic equation (PE) method has received widespread use because they are accurate and relatively fast. In this paper, Seoul National University parabolic equation (SNUPE) employing a multiplicative Padé formulation is developed. Linearization of the depth direction operator is achieved via expansion into a multiplication form of Padé approximation. To approximate the depth directional equation, Galerkin's method is used with partial collocation to achieve computational efficiency. To approximate the range directional equation, Crank–Nicolson's method is used. Finally, numerical self-starter has been used to initiate the near-field solution. The Shallow Water Acoustic Modeling (SWAM'99) Workshop provides an opportunity to test SNUPE's accuracy and compare its results with others for a variety of synthetic environments. In this paper, the numerical implementation and accuracy of SNUPE is tested by comparing with RAM12 results for the SWAM'99 test cases. Numerical experiments for SWAM'99 test cases give satisfactory results in accuracy for SNUPE and show the importance of the bottom information in the shallow water acoustic modeling.

scholarly journals Controlling the Computational Modes of the Arbitrarily Structured C Grid

2012 ◽  
Vol 140 (10) ◽  
pp. 3220-3234 ◽  
Author(s):  
Hilary Weller
Keyword(s):  
Shallow Water ◽  
Flow Direction ◽  
Water Model ◽  
Test Cases ◽  
Continuous Linear ◽  
Shallow Water Model ◽  
Advection Schemes ◽  
Water Test ◽  
Better Than ◽  
Potential Enstrophy

Abstract The arbitrarily structured C grid, Thuburn–Ringler–Skamarock–Klemp (TRiSK), is being used in the Model for Prediction Across Scales (MPAS) and is being considered by the Met Office for their next dynamical core. However, the hexagonal C grid supports a branch of spurious Rossby modes, which lead to erroneous grid-scale oscillations of potential vorticity (PV). It is shown how these modes can be harmlessly controlled by using upwind-biased interpolation schemes for PV. A number of existing advection schemes for PV are tested, including that used in MPAS, and none are found to give adequate results for all grids and all cases. Therefore a new scheme is proposed; continuous, linear-upwind stabilized transport (CLUST), a blend between centered and linear-upwind with the blend dependent on the flow direction with respect to the cell edge. A diagnostic of grid-scale oscillations is proposed that gives further discrimination between schemes than using potential enstrophy alone. Indeed, some schemes are found to destroy potential enstrophy while grid-scale oscillations grow. CLUST performs well on hexagonal-icosahedral grids and unrotated skipped latitude–longitude grids of the sphere for various shallow-water test cases. Despite the computational modes, the hexagonal icosahedral grid performs well since these modes are easy and harmless to filter. As a result, TRiSK appears to perform better than a spectral shallow-water model.

scholarly journals A New Well-Balanced Reconstruction Technique for the Numerical Simulation of Shallow Water Flows with Wet/Dry Fronts and Complex Topography

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1661 ◽  
Author(s):  
Zhengtao Zhu ◽  
Zhonghua Yang ◽  
Fengpeng Bai ◽  
Ruidong An
Keyword(s):  
Shallow Water ◽  
Water System ◽  
Reconstruction Technique ◽  
Test Cases ◽  
Bed Topography ◽  
Surface Gradient ◽  
Shallow Water Flows ◽  
Shallow Water System ◽  
The One ◽  
Flow Variables

This study develops a new well-balanced scheme for the one-dimensional shallow water system over irregular bed topographies with wet/dry fronts, in a Godunov-type finite volume framework. A new reconstruction technique that includes flooded cells and partially flooded cells and preserves the non-negative values of water depth is proposed. For the wet cell, a modified revised surface gradient method is presented assuming that the bed topography is irregular in the cell. For the case that the cell is partially flooded, this paper proposes a special reconstruction of flow variables that assumes that the bottom function is linear in the cell. The Harten–Lax–van Leer approximate Riemann solver is applied to evaluate the flux at cell faces. The numerical results show good agreement with analytical solutions to a set of test cases and experimental results.

Geoacoustic models for propagation modeling in shallow water

1982 ◽  
Vol 71 (S1) ◽  
pp. S10-S10
Author(s):  
D. M. F. Chapman ◽  
Dale D. Ellis
Keyword(s):  
Shallow Water ◽  
Propagation Modeling

GAUSSIAN RAY BUNDLE (GRAB) MODEL SHALLOW WATER ACOUSTIC WORKSHOP IMPLEMENTATION

2001 ◽  
Vol 09 (01) ◽  
pp. 133-148 ◽  
Author(s):  
RUTH ETA KEENAN ◽  
HENRY WEINBERG
Keyword(s):  
Shallow Water ◽  
Low Frequency ◽  
Test Cases

The Shallow Water Acoustic Workshop (SWAM) test cases stress low frequency propagation in shallow water environments dominated by energy refracted through the bottom. Ray based models are not normally considered applicable for such problems. The implementation and accuracy of the range dependent, Gaussian Ray Bundle eigenray model is examined for a subset of these test cases.

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