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Collisions? (Read 1321 times)
EDG
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Collisions?
11/09/10 at 19:05:37
 
I'm just wondering if there's a way to make the way that gravsim handles collisions a bit more interesting.  Apparently (as far as I can follow) asteroids belts exist because the gravity of nearby gas giants causes collisions there to be more disruptive than accretional - so large bodies don't form, and impacts tend to shatter asteroids instead.  Can this be simulated in gravsim (or is it there already?)  
 
I was thinking that if there was a away to calculate the critical collisional velocity (based on certain assumptions, I guess) then if a collision happens it could be flagged as either disruptive or accretional - if it's disruptive then both objects are deleted from the system, but if it's collisional then both objects are merged instead and now have a mass equal to the sum of the two components and an orbit determined by the collisional parameters of the two bodies.
 
I guess ideally it'd be nice to have fragments from a disrupted object, but that'd be a lot more complicated - I'm just assuming that a disrupted object is completely blown apart and no significant fragments remain that can influence anything else.  
 
I don't think my suggestion would be too computationally horrible, would it? It would certainly make asteroid belt simulations more interesting (thoughI guess it might end up depleting the belt somewhat if collisions keep being disruptive and objects disappear!).
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Tony
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Re: Collisions?
Reply #1 - 11/10/10 at 15:23:31
 
Quote from Mal on 11/09/10 at 19:05:37:
I was thinking that if there was a away to calculate the critical collisional velocity (based on certain assumptions, I guess) then if a collision happens it could be flagged as either disruptive or accretional - if it's disruptive then both objects are deleted from the system, but if it's collisional then both objects are merged instead and now have a mass equal to the sum of the two components and an orbit determined by the collisional parameters of the two bodies.

 
The latter is how it works now.  I don't know how to compute the critical velocity.  I imagine that the energy lost in the collision would need to leave the objects with velocities less than escape velocity.  A lot might depend on whether or not it was a glancing blow, or a head-on collision.  If you can figure out a formula, I could try to incorporate it.
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EDG
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Re: Collisions?
Reply #2 - 11/16/10 at 18:02:07
 
This paper by Bottke et al. might contain the equations to calculate the collisional velocities (it was referenced in another paper talking about how Jupiter's influence causes the asteroids to be disrupted rather than accrete when they collide). It's all a bit over my head, but it looks like the technical stuff starts in section 3.  
 
http://astro.mff.cuni.cz/davok/papers/excit05.pdf
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