# How to obtain 2nd-order wave pressure

Discussion in 'Hydrodynamics and Aerodynamics' started by wavebridge, Apr 24, 2017.

1. Joined: Apr 2017
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### wavebridgeNew Member

Hi everyone,

I was trying to figure out how to obtain 2nd order wave pressure on the wall of boat or structure.
Currently I am using AQWA to do hydrodynamic calculation. Since AQWA can calcuate QTF using near-field method, it must have already calculate the 2nd-order wave pressure in its process. But how to obtain that???

The available approach in other software would be helpful to me as well.

Thanks!!!!

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### jehardimanSenior Member

I'm missing your point. If you have the ANSYS AQWA Diffraction module and can get the QTF for slow drift then why would you need 2nd order wave forces? They are only the summation of the net residual.

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### wavebridgeNew Member

Hi Jehardiman,

Actually what I need is 2nd-order wave pressure, not force. And what I focus is sum-frequency force.
I believe the sum-freq force is the integral of sum-freq pressure around the body surface and AQWA must have already calcualted it but I dont know how to obtain that.

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### jehardimanSenior Member

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### wavebridgeNew Member

Hi Jehardiman,

.....my friend I know the mathematical approaches, but how to output the 2nd order pressure on every panel from software? Like AQWA

You sure WAMIT can output the 2nd term on every panel?

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### jehardimanSenior Member

You can extract it from Output Options 6 & 9

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