"Negative Damping" result on aqwa

Sengg · April 29, 2015, 23:33

Hai. Recently doing the analysis for the interaction between bodies for time response analysis of ansys aqwa.

For the irregular wave analysis which involve the convolution, the analysis is completed and results shown, but with the info of "NEGATIVE DAMPING".

May i know what is "NEGATIVE DAMPING" by meaning here?
Should i ignore the "NEGATIVE DAMPING" info? (Yes/No) Why?
If NO, which parameter or option i should edit?

Thanks in advance.

SimonR · January 11, 2017, 06:04

Hi,

I do not know you model in detail and I also do not know AQWA well. However, here's one possible explaination:

Negative damping can occur when the keel of a vessel is close to the seafloor or when vessels are close to each other. In that cases, the water gets "pushed" against the opposing surfaces. This "spring effect" can be captured as negative damping.

So there may be the possibility, that your negative damping is real.

Cheers
Simon

Edit:
Sorry, I didn't realize that this post is really old. I did not mean to be a gravedigger here...

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January 11, 2017, 06:04		#2
SimonR New Member Simon Join Date: Apr 2010 Location: Germany Posts: 1 Rep Power: 0	Hi, I do not know you model in detail and I also do not know AQWA well. However, here's one possible explaination: Negative damping can occur when the keel of a vessel is close to the seafloor or when vessels are close to each other. In that cases, the water gets "pushed" against the opposing surfaces. This "spring effect" can be captured as negative damping. So there may be the possibility, that your negative damping is real. Cheers Simon Edit: Sorry, I didn't realize that this post is really old. I did not mean to be a gravedigger here...