[shashankshankar]

Hello all,

I am trying to model and simulate a PMM test of an AUV in StarCCM+. My aim is to:-

(i) Model the vehicle in Rhino and import into Starccm+ (Completed)
(ii) Define the conditions for the body (I am looking at doing some examples now as I have not formulated my problem).


My question is, for an Underwater body (for that matter a ship also if you can help), how should I simulate PMM? I am using DFBI and tried to give PMM instead of free motion (in the boat in head waves tutorial). But I got very spurious results.

[shashankshankar]

What I commenced was I took the boat in head waves tutorial and instead of a free motion for DFBI motion, I selected the PMM carriage. Here I gave some values of the mechanism for amplitude and frequency. Also, I changed the VOF wave from 5th order to flat wave and changed all the corresponding dependencies of 5th order wave.

Any suggestions/ guidance for the final result of seeing the boat undertake sinusoidal HPMM path, please.

[Lazarus]

Originally Posted by shashankshankar

Hello all,

I am trying to model and simulate a PMM test of an AUV in StarCCM+. My aim is to:-

(i) Model the vehicle in Rhino and import into Starccm+ (Completed)
(ii) Define the conditions for the body (I am looking at doing some examples now as I have not formulated my problem).


My question is, for an Underwater body (for that matter a ship also if you can help), how should I simulate PMM? I am using DFBI and tried to give PMM instead of free motion (in the boat in head waves tutorial). But I got very spurious results.

Hey shashankshankar,

You can perform PMM tests using either DFBI(rigid mesh) or overset mesh. If you do not have an experience with overset mesh technique, you can carry out PMM tests with DFBI, readily. I remember that I had good results for PMM test with DFBI. However, as you know, do not forget to read the surge, sway forces and yaw moment according to the local frame rather than the global frame. Even if you have done all the physical setup correctly, the results you get will not be correct if you read the results from the global axis set instead of the local one.

In addition, the forces and moment results will probably have oscillations, so if you want to get the maneuvering(hydrodynamic) derivatives correctly at the end of your study, you should use the curve fitting method.

Lazarus