Changes between Version 17 and Version 18 of u/erica/OutflowFeedback


Ignore:
Timestamp:
10/17/17 18:57:51 (7 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/OutflowFeedback

    v17 v18  
    3232Now we must transition to thinking about injecting some fraction of these conservatively accreted quantities back into the grid. How is this modeled in Astrobear (i.e. what quantities do we use at the sub-grid scale/SGS) and how are these quantities distributed in a conservative fashion throughout the kernel?
    3333
    34 Question - are there any quantities that are stepped on each timestep in the kernel, or are quantities only summed/subtracted during injection/accretion steps...?
    35 
    3634
    3735== Feedback Kernel Equations ==
     
    4139$V_{out} = (\frac{G M_{sink}}{10 R_{sun}})^{1/2}$
    4240
    43 Question - how is the Bondi speed used in the accretion module? - If we can estimate the infall speed of the material around the sink as approaching the Bondi limit (is this simply pressureless collapse?), then when does $V_{out}$ >  ~ $f_a V_{bondi}$, where $f_a$ is the fraction of accreted mass to be injected in outflow.
     41If this at first seems unphysical to you because the speed is potentially greater than the flow speed of accreted material (and should be in order to get outflow), remember this is a SGS model and we envision the gas as accelerating due to gravity as it approaches the surface of the star.
     42
     43Question - how is the Bondi speed used in the accretion module? - If we can estimate the infall speed of the material around the sink as approaching the Bondi limit (is this simply pressureless collapse?), then when does $V_{out}$ >  ~ $f_a V_{bondi}$, where $f_a$ is the fraction of accreted mass to be injected in outflow. Related question - are there any quantities that are stepped on each timestep in the kernel, or are quantities only summed/subtracted during injection/accretion steps...? Thinking how does the flow change over time such that the kernel switches from infall to outflow.
     44
     45== Angular momentum injection ==
     46
     47Some preliminary thoughts here -- should jet spin up or down the encompassing cloud around a star? (Likewise, it is supposed to spin down the star right, so does this imply a counter rotating jet, or a jet that spins different directions on its top or bottom?).
     48
     49== Current Prescription ==
     50
     51Gets mass and momentum injection exact, but then guesses at angular momentum injection. At this step it can then mess up the linear momentum injection, which causes an iteration for the L again. This happens back and forth until some small error is achieved. Question -- under what circumstance does this fail? Something about discretization error in the routine, because the kernel is only 4 zones across?
     52
     53== Is the amount of "push" in the outflow subject to resolution? == 
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