Based on the inlet_shoal case, I modified the wave period to 5S and the wave is attenuated.

[刘鸿亮]

Dear FUNWAVE-TVD community users：

I have used different wave makers and found that the period is set to a smaller value, such as 5 seconds or 2 seconds. The wave height is constantly attenuating. The period of the wave maker is set to 8 seconds or higher, and the wave height is not attenuated, as shown in the picture below. is this normal? According to the weather forecast, the actual wave period on the beach at our location is 5 seconds. According to my actual observation, when the weather forecast period is 5 seconds, the situation of the waves on the shore is more like the second picture than the first picture. A continuously decaying graph. Is there anything wrong with my understanding?

The parameters of Wave maker are as follows: WAVEMAKER = WK_REG DEP_WK = 10.0 Xc_WK = 250.0 Yc_WK = 0.0 Tperiod = 5.0 AMP_WK = 1.2 Theta_WK = 0.0 operation result:

the parameters of Wave maker are as follows:

WAVEMAKER = WK_REG DEP_WK = 10.0 Xc_WK = 250.0 Yc_WK = 0.0 Tperiod = 8.0 AMP_WK = 1.2 Theta_WK = 0.0 operation result:

Attached is my elevation map and inputfile

[Matt Malej]

You don’t have enough points per wavelength to resolve the waves. Interpolate your grid (or use the slope bathy setup) to have 80 to 100 points per peak wavelength. Your dx=2.0; try dx=1.0 and 0.5 with a corresponding increase in Mglob and compare the differences in energy dissipation (wave height attenuation).

Also, watch your depth. For second order (in kh) models like FUNWAVE, your waves have to feel the bottom to be in the correct weakly dispersive regime. Meaning, wavelengths have to be at least twice the depth measure; L=Tp*sqrt(g*h) for the shallow water approximation and your Tp=2s doesn’t doesn't really fit the criteria for h=10m. 

On May 21, 2024, at 11:36 PM, 刘鸿亮 <multi...@live.com> wrote:



Dear FUNWAVE-TVD community users：

I have used different wave makers and found that the period is set to a smaller value, such as 5 seconds or 2 seconds. The wave height is constantly attenuating. The period of the wave maker is set to 8 seconds or higher, and the wave height is not attenuated, as shown in the picture below. is this normal? According to the weather forecast, the actual wave period on the beach at our location is 5 seconds. According to my actual observation, when the weather forecast period is 5 seconds, the situation of the waves on the shore is more like the second picture than the first picture. A continuously decaying graph. Is there anything wrong with my understanding?

The parameters of Wave maker are as follows: WAVEMAKER = WK_REG DEP_WK = 10.0 Xc_WK = 250.0 Yc_WK = 0.0 Tperiod = 5.0 AMP_WK = 1.2 Theta_WK = 0.0 operation result:

<y0123pjs.png>

the parameters of Wave maker are as follows:

WAVEMAKER = WK_REG DEP_WK = 10.0 Xc_WK = 250.0 Yc_WK = 0.0 Tperiod = 8.0 AMP_WK = 1.2 Theta_WK = 0.0 operation result:

<1ub4mdhf.png>

Attached is my elevation map and inputfile

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<y0123pjs.png>

<1ub4mdhf.png>

<input.txt>

<dep_shoal_inlet_new.txt>

[刘鸿亮]

Thank you, Matt. I changed my DX and DY from 2 to 0.5, and correspondingly, the dimensions of the terrain file changed from 1024x512 to 4096x1024 with interpolation, and the depth was adjusted from 10 meters to 15 meters. Now, with the wavemaker period set to 5 seconds, everything works fine as shown in the figure below. However, there is a strange issue. In my example, when the depth is increased from 10 meters to 15 meters, the result is normal. But if the depth remains at 10 meters or is less than 10 meters, the program blows up.

[Matt Malej]

Normally we recommend staying with dx/h > 1/15 ratio for stability. However, this doesn't mean other factors are not influencing your blow up; for instance your wave amplitude is 1.2m and your CFL condition is 0.5. Try lowering your CFL. 

Lastly, let me reiterate the need to have your peak wavelength L=Tp*sqrt(g*h) > 2*h, or equivalently, k*h=2*pi/L * h < pi. For surface waves beyond this range, the model accuracy decreases considerably due to errors in calculating wave celerity. My colleague Marissa Torres will soon publish a technical report on troubleshooting FUNWAVE-TVD simulations titled "Getting started with FUNWAVE-TVD: Troubleshooting guidance and recommendations". Be on a lookout for it, as I am sure it will help with these kinds of simulations. 

To view this discussion on the web visit https://groups.google.com/d/msgid/funwave-tvd/fc8d3bd9-8b16-4117-92f9-645095d6e286n%40googlegroups.com.