Learning Forum

[HAN]

I was using AQWA to find the added mass for several certain structures. I construct the structure using several points, so the only differences between all structures are their points coordinates. Is there any way to import these structures automatically or any tool I can use in ANSYS to generate hundreds of structures and run in AQWA and output added mass values automatically?n

[Ashish Khemka]

nnAqwa allows up to 50 structures in a hydrodynamic analysis model. The hydrodynamic properties such as added mass matrices of structures, which are modeled by the hull surface panels and/or tube/disc elements, can be estimated and outputted. Please use the SpaceClaim in ANSYS Workbench to import or directly define the geometry of the structures, and use Meshing tools to generate meshes, then use Hydrodynamic Diffraction in Workbench to carry out the frequency domain hydrodynamic analysis and output the results.nRegards,nAshish Khemkan

[HAN]

Hi @akhemkannThanks for the response. I know how to import one file or geometry and find the added mass. But what I need is to let some add-in program to run AQWA so that AQWA can automatically import hundreds of files and record output at somewhere. Do you have any suggestion that any add-in program can do this?n

[Niels Olsen]

Hi - I don't get how you can use ANSYS AQWA to get the added mass.

One input parameter in AQWA is the added mass coefficient, that can be calculated according to norms eg.:

DNV-RP-C205 Appendix D - there based on shapes, the added mass coefficient can be found analytical, (DNV norm can be found on the Internet).

I'm not 100% sure but I think it's this value that goes directly into AQWA, check AQWA help how added mass is defined in the program.

Another way to find the added mass is by use of CFD, eg. ANSYS Fluent.

By doing free decay test in Fluent, you can back calculate the added mass = cal. mass via formular below - total mass.

Omega = sqrt(Kw / M) and Omega = (2xpi) / T, Kw = rho x g x Aw

So from these three eq. the total mass including added mass can be found, and subsequently the sole added mass.

Hope this can be used.

KR - Niels Chr. Olsen - Norway