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05-14-2013
10:17 AM

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05-14-2013
10:17 AM

3D Directional Spectrum

I am struggling to plot the 3D directional spectrum (formula shown below) in the attached worksheet. I have plotted the 2D spectrum but need to display the 3D spectrum with theta ranging from zero to 360deg.

Any help with be much appreciated.

Mike

11 REPLIES 11

05-14-2013
10:25 AM

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05-14-2013
10:25 AM

Sorry it should read 2D. I am looking for something similar to below.

Mike

05-14-2013
11:25 AM

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05-14-2013
12:32 PM

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05-14-2013
12:32 PM

Thanks Fred that is very helpful. It's not exactly what I'm looking for but very close. I'll come back with a little more information.

Mike

05-14-2013
11:55 AM

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05-14-2013
11:55 AM

Mike Armstrong wrote:

I am struggling to plot the 3D directional spectrum (formula shown below) in the attached worksheet. I have plotted the 2D spectrum but need to display the 3D spectrum with theta ranging from zero to 360deg.

Why should theta range up to 360°? The function D.w in your worksheet would return zero for theta greater than 90°.

Attached a try without create mesh using the quickplot facility. You simply have to avoid that the first parameter is zero, so in my plot its running from 10^-10 up to 2.

The function however seems not to resemble the one from the Excel plot.

05-14-2013
12:41 PM

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05-14-2013
12:41 PM

Cheers Werner, that's a little closer. I believe it is similar but only displaying half the wave cycle.

The spectral density values seems a little low if I'm honest as the formula might not be fully correct. I'll have to check again in work tomorrow. I have just had a little play with the plot settings and it looks closer to the Excel plot.

Mike

05-14-2013
12:58 PM

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05-14-2013
12:58 PM

Running theta from -90 to +90 will give the full spectrum, but it looks like it has a rather sharp edge!?

05-14-2013
01:07 PM

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05-14-2013
01:07 PM

That does looks better again. Could you upload the worksheet please. I cannot seem to replicate the graph you uploaded.

Mike

05-14-2013
01:19 PM

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05-14-2013
01:22 PM

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05-14-2013
01:22 PM

Very nice, cheers for the help.

Mike

05-14-2013
05:19 PM

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05-14-2013
05:19 PM

You are welcome.

Just notice that your spectrum is not symmetrical around theta=0, so you won't get even the half for positive values of theta.!?

05-20-2013
07:39 AM

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05-20-2013
07:39 AM

I also noticed that, thanks Werner.

I have only had a little time to continue working on this, so it's not finished. Should have the finished worksheet shortly.

Mike