Hi Jérôme, I feel like it is a question of perspective, and undecidable overall. Is it work by gravity or work against gravity? You can find the two meanings easily. It's still a work in both cases.
OTOH it seems these energies are underdocumented overall. I did not find a list of available energies anywhere in the doc. I must say trackEnergy=True is slow. It computes many un-needed things (gravitational work is a good example, why should we increment G-=g*vel*dt at every iteration while we can get at any point in time -g*pos? same issue with elastic work). In current design I would not recommend it although it is elegant and handy for quick tests. Cheers Bruno So Bruno On Mon, 20 Apr 2020 at 16:13, Jerome Duriez <jerome.dur...@inrae.fr> wrote: > I now think the most logical would be to keep this expression with a > minus sign [*], but rename 'gravWork' into 'gravPotential' (like we have > 'elastPotential'). > > It would reconcile for me the name with the coded expression, and be > more logical with the existence of O.energy.total() function (which sums > all terms in O.energy and certainly is expected to be constant) > > > Thoughts ? > > [*] > > https://gitlab.com/yade-dev/trunk/-/blob/master/pkg/dem/NewtonIntegrator.cpp#L85 > > ------ > Chargé de Recherche / Research Associate > Inrae, RECOVER > 3275 route Cezanne – CS 40061 13182 Aix-en-Provence Cedex 5 FRANCE > +33 (0)4 42 66 99 21 > > https://www6.paca.inrae.fr/recover/membres-du-laboratoire/pages-personnelles/jerome-duriez > > On 20/04/2020 10:25, Jerome Duriez wrote: > > Hi, > > > > Is there a consensus (outside myself) for the extra minus sign in > > O.energy['gravWork'], computed in NewtonIntegrator at [*]. > > > > It seems that code line was initially introduced by Vaclav in > > GravityEngine in commit [**] (and made finally its way into > > NewtonIntegrator). > > > > As far as I'm concerned, I can not make sense of the comment justifying > > that sign, just above [*], neither of a consequent negative power of > > weight during some free fall. > > > > > > Jérôme > > > > > > [*] > > > https://gitlab.com/yade-dev/trunk/-/blob/master/pkg/dem/NewtonIntegrator.cpp#L85 > > > > > > [**] > > > https://gitlab.com/yade-dev/trunk/-/commit/d41480acf2ad616268c9ed562b625952c87c98a5, > > > see also corresponding file from that time at > > > https://gitlab.com/yade-dev/trunk/-/blob/d41480acf2ad616268c9ed562b625952c87c98a5/pkg/common/GravityEngines.cpp#L33 > > > > ------ > > Chargé de Recherche / Research Associate > > Inrae, RECOVER > > 3275 route Cezanne – CS 40061 13182 Aix-en-Provence Cedex 5 FRANCE > > +33 (0)4 42 66 99 21 > > > https://www6.paca.inrae.fr/recover/membres-du-laboratoire/pages-personnelles/jerome-duriez > > > > _______________________________________________ > Mailing list: https://launchpad.net/~yade-dev > Post to : yade-dev@lists.launchpad.net > Unsubscribe : https://launchpad.net/~yade-dev > More help : https://help.launchpad.net/ListHelp > -- -- _______________ Bruno Chareyre Associate Professor ENSE³ - Grenoble INP Lab. 3SR BP 53 38041 Grenoble cedex 9 Tél : +33 4 56 52 86 21 ________________ Email too brief? Here's why: email charter <https://marcuselliott.co.uk/wp-content/uploads/2017/04/emailCharter.jpg>
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