Changes between Version 13 and Version 14 of u/erica/d


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Timestamp:
12/14/15 14:20:44 (9 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/d

    v13 v14  
    7272Thus, we envision a ring of flux surrounding the colliding flows cylinder R that is carried outward away from the cylinder boundary. It comes to some steady state in the ambient by developing a magnetic pressure gradient that counterbalances magnetic tension. At the rings outer boundary, the magnetic pressure is balanced with the initial unperturbed magnetic pressure. At the rings inner boundary, the magnetic pressure is balanced with ram pressure from the colliding flows.
    7373
     74Now, the ram pressure as a function of r from the cylinder's center is given by:
     75
     76[[latex($P_{ram} = \rho v^2(\frac{R}{r})^2$)]]
     77
     78(assuming spherical dilution of a constant radial velocity ejecta), where R is the radius of the CF cylinder.
     79
     80Balancing ram pressure and magnetic pressure at the rings inner edge gives:
     81
     82[[latex($\rho v^2(\frac{R}{r_i})^2 = B_0^2(\frac{r_0}{r_i})^2$)]]
     83
     84or
     85
     86[[latex($\boxed{r_0 = \sqrt{\beta_{ram}} R}$)]]
     87
     88which for our sims gives
     89
     90[[latex($\boxed{r_0 \approx 6R}$)]]
     91
     92Our ring has not yet reached steady state, so the outer boundary of the ring may come to rest at about 6R. What about for the inner radius of the ring? To get this we use flux-freezing, i.e.,
     93
     94[[latex($\theta_1 = \theta_2$)]]
     95
     96where
     97
     98