Changes between Version 3 and Version 4 of AstroBearProjects/multiphysics

Timestamp:

02/14/12 14:46:03 (14 years ago)

Author:

Shule Li

Comment:

—

AstroBearProjects/multiphysics

@@ -216 +216 @@
 
 ''
+
+'''Thermal Conduction''' [[BR]][[BR]]
+
+The anisotropic thermal conduction is determined by the following equations: [[BR]][[BR]]
+
+
+Another user controlled isotropic thermal diffusion is added to make the code stubborn. There are . The microphysical thermal conduction is also flux limited, heat flow at each cell face [[BR]]
+centers cannot surpass a fraction of electron mean thermal speed (Cowie, Mckee 1977):
+
+
+However, the user controller isotropic thermal conduction is not included in this limiting. [[BR]]
+It is supposed to be several orders of magnitudes smaller than the microphysical conductivity, and should maintain isotropic. [[BR]]
+
+The thermal conduction is implemented in a similar manner as the resistivity. [[BR]]
+First, the heat flux at each cell centers are calculated: on x interfaces, qx are directly obtained, qy is obtained by averaging the adjacent 4 qy, Same for y interfaces.[[BR]]
+We do projections of heat flux twice: first onto the field direction, then to the face normal.[[BR]][[BR]]
+
+
+We also calculate the saturation flux and project to the face normal. Remember, the saturation flux is always aligned with the field.[[BR]][[BR]]
+
+
+Both the projected heat flux and saturation flux are feed into the saturation function to calculate the final flux. The saturation starts at a "saturation point", which is controllable. [[BR]]
+Below the saturation point, there is no saturation so there is no additional modification to the original heat flux. Above the saturation point, the flux gets saturated and gradually reach [[BR]]
+the saturation flux. [[BR]][[BR]]
+
+
+
+'''Thermal Conduction Interface''' [[BR]]
+The anisotropic thermal conduction can be turned on by putting: [[BR]]
+'''lresistive = .true.'''[[BR]]
+The '''CondType''' controls the type of conduction:[[BR]]
+CondType = 1: computational conductivity, linear, only alone the field lines. CondType = 2: computational conductivity, nonlinear, only alone the field lines.[[BR]]
+CondType = 3: microphysical conductivity, automatically calculated and scaled. [[BR]]
+'''conductivity''': effective only when the conductivity is computational. [[BR]]
+'''lisodiffusion''': a bool that controls whether there is artificial thermal diffusion. This diffusion is isotropic.[[BR]]
+'''isodiffusionratio''': controls the ratio between artificial diffusion and actual diffusion. For instance, setting this ratio to 0.01 will add an artificial isotropic thermal diffusion [[BR]]
+ that is 100 times weaker than the minimal actual diffusion on the grid. [[BR]]
+
+
+
 
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