# About Regular Wave Generation

have recently started using DualSPHysics and have a question about Wave generation.

The purpose of this analysis is to understand the characteristics of wave generation in DualSPHysics, and I am running the program to see if waves are generated according to the values for the input wave height and period. Therefore, some of the conditions may be a little strange.

First of all, we used examples→main→09_WavePiston to generate regular waves in 2D.

The main conditions entered were: wave height: 0.2 m, period: 2.0 s, dp: 0.02 m, wavelength: 1.56 m, wave height/wavelength: 0.13

coefh value: 1.2, and

The following model was used for the analysis. The white lines are the measurement points using wg, and the red marks above them are the measurement points (x=1m, x=5m, x=10m) for the results shown here.

This analysis was performed for 100s, and the results from 40 to 70s during the course of the analysis are shown below.

Comparing x = 1m (light blue) and x = 5m (yellow), the average η at 1m is 0.19m and at 5m the average η is 0.19m.

Next, comparing x=1m (light blue) and x=10m (green), the average η at 1m was 0.19m and at 10m the average η was 0.19m.

Next, the model analyzed in 2D was converted to 3D to check the wave output.

The main conditions input were: depth: 2.0 m, wave height: 0.15 m, period: 1.0 s, dp: 0.015 m, wavelength: 1.56 m, wave height/wavelength: 0.01, coefh value: 1.5.

The following model was used for the analysis. The white lines are the measurement points using wg, and the red marks above them are the measurement points (x=1m, x=5m, x=10m) for the results shown here.

The results of this model in 3D are shown below.

Comparing x =1m (light blue) and x=5m (yellow), the average η at 1m is 0.14m and at 5m the average η is 0.09m.

Next, comparing x=1m (light blue) and x=10m (green), the average η at 1m was 0.14m and at 10m the average η was 0.06m.

There are two questions I would like to ask in response to these results.

1. why does the conversion of the 2D analysis to 3D result in errors in the input and output wave heights?

2. why the wave heights become smaller as the wave progresses in the 3D results

I would like to ask about the above two points.

Thank you in advance.

## Comments

Please note that the code is designed to study wave-structure interaction... therefore our code is not ideal for wave propagation alone!

Then, we know we can get a proper wave propagation for 3 wavelengths, but no more... using coefh=1.5 perhaps a bit more.. but that is it...

To get a better wave propagation for several wavelengths we will have to use other more sophisticated algorithms that are not available in the online version

Regards