COMMON ENVELOPE SIMULATIONS

New Work

  1. Addressing a difficult issue with making VisIt plots.
  2. More analysis if high res run 132
    • Movies centered on P2 that include velocity vectors (in inertial frame).
    • Graph of accretion rate vs time.

Summary of New Results

  1. Extracting information from one of the particles to use in the variable expressions in VisIt is proving to be extremely non-trivial. Baowei is working on this, but it probably merits a workaround from within astrobear (defining each particle to be a separate subset of the mesh 'particles' might do the trick). Otherwise, as it stands now, one cannot plot within VisIt, for example, the gravitational potential due to a particle, or the gas velocity vectors in the reference frame of the particle.
  2. Results:
    • Edge-on movies show a transient global vertical flow through the center of the torus that changes direction with time.
    • The accretion rate from the Krumholz prescription is of order 1 Msun/yr, which seems too large.

Run 132 that uses twice as high resolution and 10x lower ambient pressure as previous runs:

Binary run 132 with double max resolution, lower resolution in ambient medium, 10x smaller ambient pressure than run 116
Relaxation run: 129
First frame: 75 (5 RG freefall times, when velocity damping ended)
Last frame:
Total simulation time:
Machine and partition: Stampde 1 normal/Bluehive 2.5 standard/Bluestreak standard (completed up to frame 375, or 70 sim-days)
Number of cores: 1024
Total wall time: around 14 days (starting from frame 75 of relaxation run)
Hydro BCs: extrapolated
Poisson BCs: multipole expansion
Box size: L=4e13 cm (575 Rsun)
Base resolution: 2.25 Rsun (2563 cells)
Highest resolution: 0.14 Rsun (40963 cells, 4 levels AMR)
AMR implementation: set by hand to have max level around point particles
Max resolution zone: within 5e12 cm (71.87 Rsun) of primary center and within a cylinder of radius 20 Rsun and height 20 Rsun around secondary center. After t~11d (~frame 123) refinement radius around primary was halved to 2.5e12cm (36Rsun). After t~31d (frame 210) halved again to 1.25e12cm (18Rsun).
Buffer zones: 2 cells
Softening length: 2.4 Rsun
Ambient density: 6.7e-9 g/cc
Ambient pressure: 105 dyne/cm2
DefaultAccretionRoutine=2 (Krumholz)

New Movies of run 132
1) Edge-on , centered at P2, with velocity vectors (relative to inertial frame). Left: slice through both particles. Right: slice through P2 as viewed from direction of P1.
​edge-on with velocity vectors (relative to inertial frame)
2) Face-on , centered at P2, with velocity vectors (relative to inertial frame).
​face-on with velocity vectors (relative to inertial frame)

Comments:

  • Movie (1) shows that there is a significant vertical flow of gas of order up to a few times 107 km/s.
    • The velocity vectors are in the inertial frame whereas the movie is in the frame of P2. However, the orbital velocity of P2 is at all times less than 107 km/s so the largest vectors shown would be almost unchanged if they were plotted with respect to the velocity of P2. Moreover P2 has close to zero vertical velocity.
    • The vertical flow is present only when the torus is present.
    • Even when the torus is present, the vertical flow is intermittent.
    • When the vertical flow is present it is located in the 'hole' of the torus where the density is low.
    • When the vertical flow is present the flow is either upward below and above the orbital plane, or downward below and above the orbital plane, unlike a jet, which would be upward above the midplane and downward below.
    • Roughly speaking, it switches from downward (frames 36-40) to non-existent to upward (frames 75-99) to non-existant to downward (frames 119-152) to non-existent to downward (frames 164-168).
  • Movie (2) shows rotation around the secondary.

Accretion rate
http://www.pas.rochester.edu/~lchamandy/Graphics/RGB/Post-sink_particle/Post-modified_Lane_Emden/Damp132/m2_Damp132.png http://www.pas.rochester.edu/~lchamandy/Graphics/RGB/Post-sink_particle/Post-modified_Lane_Emden/Damp132/p_Damp132_simple.png

Next steps

  • Compute accretion rate using alternative prescription using mass within a sphere centered at the secondary.
  • Compute drag force.
  • New simulation with a jet.
    • Use outflow object in astrobear.
    • Can take mdot from RT08/12.
    • Velocity of order 100 km/s (or escape veloc at ~1 solar radius say).
    • Half opening angle ~10 degrees.
  • Plot CM position of system as a function of time.

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