Changes between Version 15 and Version 16 of u/BonnorEbertMatched2
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 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 setup 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 outsidein 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 setup 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 xaxis is logarithmic and begins at the length of the smallest zone dx. The yaxis is linear: http://www.pas.rochester.edu/~erica/BPJuly22.gif . The collapse here resembles the B&P results, namely collapse proceeds in an outsidein 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.