Moments of inertia: request for documentation
This is a fork of the post GenCase v 5.0.174 and calculation of moments of inertia at https://forums.dual.sphysics.org/discussion/comment/3727/#Comment_3727 (July 2020). For this part can live independently of the continuation there, I split that to avoid oblivion.
I would politely ask to include the following items in the documentation set of DualSPHysics 5.0.
First, one certain outcome of that discussion is that custom-setting the inertia matrix for floating objects is an important, perhaps necessary, option. Would you please add to the XML documentation of 5.0 (XML_GUIDEv5.0.pdf, section 2.6, p.71) which moments of inertia you model in DualSPHysics? I presume that the moments of inertia you have in mind are those with respect to axes parallel to the DualSPHysics reference system and passing through the centre of mass of the object (https://forums.dual.sphysics.org/discussion/comment/3099/#Comment_3099, June 2019). However, the guide still lacks guidance on this topic.
Second, would you mind it to align the User’s Guide to that description? Not unlike some peer-reviewed publications, the formulation at https://github.com/DualSPHysics/DualSPHysics/wiki/3.-SPH-formulation#384-fluid-driven-objects still speaks about a single, scalar moment of inertia, while in the general 3D case it should be a tensor/matrix.
Finally, I understand that GenCase is a closed-source program and am fine with it. Would you mind it, nonetheless, to mention in the User’s Guide which algorithm you use for computing the six elements of an inertia matrix? I would expect an embarrassingly parallel summation of particle masses time squared distances,, but I understood that there may be other ways; naming those would be appropriate, I believe.
Thanks in advance for this. I trust that the documentation will be clearer for the benefit of any reader interested in modelling floating objects.