War Wheel wrote:Just to get this through my skull, are we talking about mass loss from the objects being pulverized at the crush front, or mass working its way loose from the accretion blob?
The former; mass loss from the 'upper block' as it descends, not
entraining material but rather paring down erosively or even catastrophically.
The blob is going to have a structure like the pretty picture. It's basically a giant dust bunny (only heavier).
If instead the upper block is considered the dust bunny (with some dense and strong components, not necessarily both), and if DLA were extended with a negative range of sticking coefficients which allowed for breaking pieces off the aggregate as well as sticking, then I think that describes the situation I'm imagining. The simple 1D accretion models would have a sticking coefficient of 1 in this scheme, and it's pretty obvious that didn't really happen. What I see is a reaction proceeding in both directions but dominated early on by loss, a scenario which, if interpreted within the framework of accretion (a mistake) would lead to a slower collapse front progression. If interpreted correctly, it provides a means of achieving the natural terminal velocity more rapidly via less resistance at the lower velocities and a steeper rise of resistance as the mode switches over to accretion. That would happen (excluding a deflection-dominated phase in between - cleaver mode - but that's another subject) because:
If the "ablation" rate ends up being a function of velocity (intuitively seems so), the hammer driving the nail will tend to converge on a distinct size and maintain.
Most astute! Yes, and I think that final form will preferentially be a hard dense nugget as the 'dust' of the dust bunny gets blown away, with a shape and orientation suitable for the cleaver stage, otherwise it wouldn't happen. But, if it can happen, it should. I think it could be a wedge composed of some part of core, perimeter and hat truss, with interstitial flooring, slipped inside the south perimeter.
Or the race-ahead in the SW could be the shock of the whack (harmless elastic waves), rapid eccentric loading ripping the structure apart, or a series of charges.
Now, I should stop derailing the topic. There are many curious things visible in the video, these should be discussed.