Changes between Version 15 and Version 16 of u/BonnorEbertMatched2
- Timestamp:
- 10/15/12 21:42:15 (12 years ago)
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u/BonnorEbertMatched2
v15 v16 46 46 '''!Results/Analysis''' 47 47 I. Movies 48 49 '''Stability''' 50 51 Stability test of the critical BE sphere placed in an ambient rho=0.01rho(Rbe), with sphere and ambient in pressure equilibrium at r=Rbe. This is just the B&P sphere, with no density enhancement, in a box twice as large. My apologies, but the movie is broken into 2, with the first half here: https://clover.pas.rochester.edu/trac/astrobear/attachment/wiki/u/BonnorEbertMatched/rhoCroppedLight.gif and second half here: https://clover.pas.rochester.edu/trac/astrobear/attachment/wiki/u/BEmoviesLonger/rhoSecondHalf.gif. This set-up was stable to collapse for at least 5 crossing times, where 1 tc= 0.2 in computational units, as can be seen from this 2d slice through the center of the sphere. Here the sphere is breathing about its equilibrium initial condition. 52 53 [[Image(rhoLight.png, 20%)]] 54 [[Image(vradLight.png, 20%)]] 55 [[Image(lineoutStabilityCheck.gif, 20%)]] 56 48 57 '''B&P, classic outside-in collapse''' 49 58 … … 54 63 [[Image(BPJuly22.gif, 20%)]] 55 64 56 57 '''Stability'''58 59 Stability test of the critical BE sphere placed in an ambient rho=0.01rho(Rbe), with sphere and ambient in pressure equilibrium at r=Rbe. This is just the B&P sphere, with no density enhancement, in a box twice as large. My apologies, but the movie is broken into 2, with the first half here: https://clover.pas.rochester.edu/trac/astrobear/attachment/wiki/u/BonnorEbertMatched/rhoCroppedLight.gif and second half here: https://clover.pas.rochester.edu/trac/astrobear/attachment/wiki/u/BEmoviesLonger/rhoSecondHalf.gif. This set-up was stable to collapse for at least 5 crossing times, where 1 tc= 0.2 in computational units, as can be seen from this 2d slice through the center of the sphere. Here the sphere is breathing about its equilibrium initial condition.60 61 [[Image(rhoLight.png, 20%)]]62 [[Image(vradLight.png, 20%)]]63 [[Image(lineoutStabilityCheck.gif, 20%)]]64 65 65 66 '''Matched''' … … 72 73 73 74 74 II. Approximations/Quantitative Estimates?75 II. !Approximations/Quantitative Estimates? 75 76 III. Quantitative calculations on sim. specific quantities? 76 77 IV. Figures … … 85 86 86 87 87 88 89 90 I ran a series of simulations to study the deviation from the 'classic' collapse studies of the BE sphere - a slight increase in density values above equilibrium of a critical sphere (xi=6.5) in pressure equilibrium with its environment (Foster and Chevalier, 1993, Banerjee and Pudritz, 2003). My simulations were all variations of the B&P setup, but with a sphere in a domain twice the size (~30 Rbe), and varying ambient densities. These runs are as follows:91 92 93 94 2) 'Classic B&P collapse' of a BE sphere. That is, 10% density enhancement of sphere above equilibrium values, in pressure equilibrium with a light (rho=0.01rho(Rbe) ) ambient. This, as well as the following plots, show lineouts through the center of the sphere of the quantities: rho, absolute value(radial velocity), absolute value(mach), and pressure, all normalized to their initial values in the grid. The x-axis is logarithmic and begins at the length of the smallest zone dx. The y-axis is linear: http://www.pas.rochester.edu/~erica/BPJuly22.gif . The collapse here resembles the B&P results, namely collapse proceeds in an outside-in fashion and remains subsonic most of the way through.95 96 97 98 99 100 88 In summary, I would say that the runs in which collapse was NOT induced to occur through a density enhancement, seem to proceed much differently. They resembled qualitatively the runs by Hannebelle et al., in which a pressure wave moved through the sphere, causing collapse into a sink particle. The resolution of these sims became poor by the time the apparent wave has moved into the sphere, so the simulation was killed ostensibly before a sink formed. I can run these simulations out longer and at higher resolution as a next step if you suggest. This however, will be postponed until after I take the preliminary PhD written exam, due to take place at the end of August.
