Changes between Version 16 and Version 17 of u/erica/OutflowFeedback
- Timestamp:
- 10/17/17 18:47:48 (7 years ago)
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u/erica/OutflowFeedback
v16 v17 1 = Kernel Equations=1 = The Outflow Feedback Module in AstroBEAR = 2 2 3 3 The outflow module injects a fraction of accreted mass, momentum and angular momentum back into the grid following each accretion time step and between hydro advances. … … 32 32 Now 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? 33 33 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 36 34 37 == Feedback Kernel Equations == 38 39 First off, injected mass will only flow back *out* into the grid (after placed into the kernel) if the injected outward directed momentum in the ith cell is greater than 2x the momentum of the ith cell (right?).. This immediately implies the need for a high injection speed of the material. So, how is this speed modeled at the SGS? 40 41 $V_{out} = (\frac{G M_{sink}}{10 R_{sun}})^{1/2}$ 42 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. 35 44 36 45