| | 79 | |
| | 80 | == THE SIGNIFICANCE OF R_jet: PART 2 == |
| | 81 | |
| | 82 | The series of sims below is similar to the one that I sent yesterday with these exceptions: the opening angle of the Gaussian-tapered flow is 15 deg, not 45, and the structure of the ambient (environment) gas includes the torus in addition to the AGB wind. In this case the outcomes of each of the Rjet sims is similar in shape but not in size. Oddly, it is the Rjet=2 sim in which add behavior develops near the y axis. |
| | 83 | |
| | 84 | |
| | 85 | [[Image(https://dl.dropboxusercontent.com/s/jpowp2k0jwhc8d7/rjet2.jpg?dl=0)]] |
| | 86 | |
| | 87 | Comments on size: The mass and momentum in the Rjet = 2 sim is 4x larger than that in the Rjet = 0.5 case, so the flow penetrates further as Rjet increases. However, the odd knot that develops near the y axis -- combined with the fact that the flow barely encounters the torus on its lateral edge -- mean that the head of the flow spreads out laterally and accretes more ambient with time. This slows it down. |
| | 88 | |
| | 89 | Comments on shape: Although the general pattern of the flow stays about the same, the width-to-length ratio increases with Rjet. No surprise here, of course, Interestingly the flow width is set right at the earliest times by the size of the flow orifice. The width is not affected appreciably by the thermal pressure in the backflow. |
| | 90 | |
| | 91 | Conclusions: in the narrow-flow sim (<~15-deg spread) the torus isn't a significant shaping factor. So for njet < namb the shape of the outflow is controlled largely by the initial conditions of the flow: vjet, jet mass, and opening angle. njet plays a role in determining the length of the jet. Rjet determine sits width. It appears safe to run models with a small Rjet since the issues that we saw in the email of yesterday (artificial structure forming near the y axis in the first 100 years) don't materialize for the narrower flows. |
| | 92 | |
| | 93 | OVERALL CONCLUSIONS |
| | 94 | |
| | 95 | It seems from this that the sims with small Rjet (that is, a high degree of flow-surface pixelation) work well other than the jet width is determined by initial conditions and not the flow hydro. For larger values of Rjet (that is, more diffuse momentum flux after launch) Rjet should be at least two (or the number of AMR refinement levels should be incremented by two) or else odd behaviors that develop at early times are amplified as the flow evolves will have a huge impact ont eh structure of the flow along its leading edge. |
