Long wave propagation: Difference between revisions

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The purpose of this verification test is to assess the model performance in simulating long wave propagation.  The case is also useful for testing the model performance and symmetry for a non-rectangular domain. The test case consists of a quarter annulus with a linear bed elevation in the radial direction. The inner radius is 60.96 km (200,000 ft), and the outer radius is 152.4 km (500,000 ft). The analytical is given by Lynch and Gray (1978).  
The purpose of this verification test is to assess the model performance in simulating long wave propagation.  The case is also useful for testing the model performance and symmetry for a non-rectangular domain. The test case consists of a quarter annulus with a linear bed elevation in the radial direction. The inner radius is 60.96 km (200,000 ft), and the outer radius is 152.4 km (500,000 ft). The analytical is given by Lynch and Gray (1978).  


Table 1. General Settings for Flow over a Bump
'''Table 1. General Settings for Flow over a Bump'''
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A Cartesian grid is used with two levels of refinement. The computational grid is shown in Figure 1. The general model settings are shown in Table 2.
A Cartesian grid is used with two levels of refinement. The computational grid is shown in Figure 1. The general model settings are shown in Table 2.


Table 2. General Settings for Flow over a Bump
'''Table 2. General Settings for Flow over a Bump'''
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The figure below shows a time series of water levels at the inner edge of the model domain. The goodness of fit statistics are listed in the below. The model accurately predicts the wave phase but slightly overestimates the amplitude by approximately 0.01 m.  
The figure below shows a time series of water levels at the inner edge of the model domain. The goodness of fit statistics are listed in the below. The model accurately predicts the wave phase but slightly overestimates the amplitude by approximately 0.01 m.  


Table 3. Goodness of fit statistics for the water elevation
'''Table 3. Goodness of fit statistics for the water elevation'''
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Revision as of 23:27, 3 March 2011

Analytical Solution

The purpose of this verification test is to assess the model performance in simulating long wave propagation. The case is also useful for testing the model performance and symmetry for a non-rectangular domain. The test case consists of a quarter annulus with a linear bed elevation in the radial direction. The inner radius is 60.96 km (200,000 ft), and the outer radius is 152.4 km (500,000 ft). The analytical is given by Lynch and Gray (1978).

Table 1. General Settings for Flow over a Bump

Parameter Value
Deepwater Tidal Amplitude 0.3048 m
Tidal Period 12.42 hrs (M2)
Bottom friction None
Horizontal eddy viscosity None

Model Setup

A Cartesian grid is used with two levels of refinement. The computational grid is shown in Figure 1. The general model settings are shown in Table 2.

Table 2. General Settings for Flow over a Bump

Parameter Value
Time step 600 sec (10 min)
Ramp period 24 hrs
Simulation time 120 hrs
Grid resolution 2-8 km
Number of active ocean cells 1160
Wall friction Off
Figure 1. Quarter Annulus


Results

The figure below shows a time series of water levels at the inner edge of the model domain. The goodness of fit statistics are listed in the below. The model accurately predicts the wave phase but slightly overestimates the amplitude by approximately 0.01 m.

Table 3. Goodness of fit statistics for the water elevation

Statistic Value
RMSE 0.014 m
RMAE 0.028
R^2 0.999
Bias 0.003 m

QA Water Level 8km.png


References

  • Lynch, D.R., and Gray, W.G. (1978). "Analytical solutions for computer flow model testing," J. Hydraulics Division, 104, 1409-28.

Test_Cases