Changes between Version 1 and Version 2 of AstroBearProjects/MagnetizedClumps

Timestamp:

07/04/11 18:35:21 (14 years ago)

Author:

Shule Li

Comment:

—

AstroBearProjects/MagnetizedClumps

@@ -5 +5 @@
 There are several ways to obtain the equilibrium state of a magnetized cloud. The easiest way is to set up a magnetic field distribution with random frequency spectrum inside the cloud and find out the magnetic pressure at each point. Then set up the cloud with constant density but varying temperature so that the thermal pressure at each point exactly balances the magnetic pressure. Outside the cloud, the magnetic field is cut off. So the thermal pressure equals the total pressure. The next few animations show such a magnetized cloud with various magnetic beta.
 
-beta = 10
+beta = 10[[BR]]
+[http://www.pas.rochester.edu/~shuleli/dens_b10.gif GIF:density][http://www.pas.rochester.edu/~shuleli/beta_b10.gif GIF:beta][[BR]]
 [[Image(http://www.pas.rochester.edu/~shuleli/dens_b10.png, 40%)]][[Image(http://www.pas.rochester.edu/~shuleli/beta_b10.png, 40%)]]
 
-beta = 4
+beta = 4[[BR]]
+[http://www.pas.rochester.edu/~shuleli/dens_b4.gif GIF:density][http://www.pas.rochester.edu/~shuleli/beta_b4.gif GIF:beta][[BR]]
 [[Image(http://www.pas.rochester.edu/~shuleli/dens_b4.png, 40%)]][[Image(http://www.pas.rochester.edu/~shuleli/beta_b4.png, 40%)]]
 
@@ -16 +18 @@
 Another approach is to set up a cloud as above, and then let it evolve for a period of time to let the field relax to some steady state. With this method, we can achieve magnetized cloud with any desired field spectrum since the only thing we need to do is throw in the field and let it treat itself. The down side of this method though, is that (1) for large simulations with multiple magnetized clump, it can take very long to reach a force free state and we have no time how long it will take. (2) it does not work with low beta. as shown in the following two animations with beta = 1 and beta = 0.2, the density imbalance grows to more than 20%. 
 
-beta = 1
+beta = 1[[BR]]
+[http://www.pas.rochester.edu/~shuleli/dens_b1.gif GIF:density][http://www.pas.rochester.edu/~shuleli/beta_b1.gif GIF:beta][[BR]]
 [[Image(http://www.pas.rochester.edu/~shuleli/dens_b1.png, 40%)]][[Image(http://www.pas.rochester.edu/~shuleli/beta_b1.png, 40%)]]
 
-beta = 0.2
+beta = 0.2[[BR]]
+[http://www.pas.rochester.edu/~shuleli/dens_b02.gif GIF:density][http://www.pas.rochester.edu/~shuleli/beta_b02.gif GIF:beta][[BR]]
 [[Image(http://www.pas.rochester.edu/~shuleli/dens_b02.png, 40%)]][[Image(http://www.pas.rochester.edu/~shuleli/beta_b02.png, 40%)]]
 
@@ -97 +101 @@
 It is easy to prove that this solution satisfies the force free equation by using the derivative relations of Bessel functions.[[BR]][[BR]]
 
-The magnetic energy of this set up is plotted below. No cut off is applied here to zero out the field energy outside the cloud, so we can see the field energy similar to point diffraction patterns extending into the outer area. We can see that the setup has nice centralized field energy inside the cloud while the field does not exert any force on the cloud material. Another nice feature about this setup is that the field has no radial component so that it will be an equilibrium even if there is an anisotropic conduction along field lines.[[BR]]
+The magnetic energy of this set up is plotted below. No cut off is applied here to zero out the field energy outside the cloud, so we can see the field energy similar to point diffraction patterns extending into the outer area. We can see that the setup has nice centralized field energy inside the cloud while the field does not exert any force on the cloud material. Another nice feature about this setup is that the field has no radial component so that it will be an equilibrium even if there is an anisotropic conduction along field lines.[[BR]][[BR]]
+[http://www.pas.rochester.edu/~shuleli/dens_b10.gif GIF:Simple Cloud Solution, Magnetic Pressure][[BR]]
 [[Image(http://www.pas.rochester.edu/~shuleli/simplecloud.png, 40%)]][[BR]][[BR]]