CFD Online Discussion Forums - [waves2Foam] Reflection analysis for a flat wave flume

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Reflection analysis for a flat wave flume

Hi All:

I am doing a reflection analysis for a flat wave flume.

I use stokes first order wave with H = 0.02 and T = 2s, the surface elevation seems reasonable but the reflection coefficients goes to 1.27 which is obvious wrong....

and I can not see why a0 goes to infinite...

I attach the postprocessing file and the results:

Code:

deleteParentOutputDirectory false;



regularSpectrum

{

    callName          surfaceElevation;



    removeDuplicate   true;

    inputDir          surfaceElevation;



    deltaT            0.01;

    tMin              7.0;  // Default: minimum time

    tMax              15.0; // Default: maximum time



    // indices                       4 (2 3 4 5);



    // The action list is a set of processes on the data

       actionList (interpolateSurfaceElevation reflectionAnalysis2DLS write2Ascii removeData);

    depth     1;

    coordName x;



    // Removal of outputted data in the <callName> directory

    removeOF    false;    // Default value = true;

    removeAscii false; // Default value = false;

    waveNumber  (1.2047 0 0);

    nFreq       6;

    period      2.0;

    allDataSets true;

}

leftGoing:

Code:

1    0.0145989

1    0.00537883

2    -0.00140605

2    0.0220935

3    0.0194711

3    0.0464041

4    -0.0185462

4    0.0159688

5    0.00337293

5    0.00671671

6    -0.0866702

6    -0.0321751

0    -6.25e+13

rightGoing

Code:

1    -0.0279252

1    -0.00912701

2    0.0259962

2    -0.0131003

3    -0.0280987

3    0.0040698

4    0.033124

4    -0.017982

5    0.0243494

5    -0.00611838

6    -0.0167575

6    -0.0231503

0    -6.25e+13

Any help are appreciated! Thanks!

Best regards
Hao

Good evening Hao,

Your mean surface elevation (frequency index 0) is -6.25e+13, so you are probably doing something wrong. I cannot, however, come with any suggestions for improvements based on your information.

Kind regards,

Niels

Hi Niels:

Does this utility only use this input file or it also reads some data from other files like waveParameters? I check the interpolated surface elevation and there is one file called 'surfaceElevation_indexXYZ.txt' it looks like:

Code:

0    -5e-09    5e-08    1.49418

1    1    0    0.3

2    2    0    0.3

3    3    0    0.3

4    4    0    0.3

5    5    0    0.3

6    6    0    0.3

7    7    0    0.3

8    8    0    0.3

9    9    0    0.3

10    10    0    0.3

11    11    0    0.3

12    12    0    0.3

13    13    0    0.3

14    14    0    0.3

15    15    0    0.3

I do not know what is the meaning of these data?

Best regards
Hao

Hi Hao Chen,
I'm new in using OpenFOAM and I'm trying to perform the 2DFFT reflection analysis and the resultant value is greater than 1 as in your case (even if you used the LS method).
Did you understand how to perform this analysis?? Can you help me?
Giusy

reflection coefficient

Hi,
could somebody help me to calculate reflection coefficient? I did reflectionAnalysis2DLS, but I don't understand what is exactly the leftGoing and rightGoing results:confused: It would be very appreciated if somebody could send me the postProcessingPropertiesdictionary and tell me how to obtain reflection coefficient from the output!

Sanaz