version 4.2 authored by Udo Ziegler's avatar Udo Ziegler
...@@ -1621,7 +1621,7 @@ log *T*, both as functions of the logarithm of mass density log 𝜚 ...@@ -1621,7 +1621,7 @@ log *T*, both as functions of the logarithm of mass density log 𝜚
and the logarithm of thermal energy density *ε*. and the logarithm of thermal energy density *ε*.
The look-up tables for a prescribed (log 𝜚, log *ε*)-range The look-up tables for a prescribed (log 𝜚, log *ε*)-range
are generated by cubic interpolation from user-specified data are generated by cubic interpolation from user-specified data
{(log *p*)<sub>*ij*</sub>} and ({(log *T*)<sub>*ij*</sub>}) {(log *p*)<sub>*ij*</sub>} and {(log *T*)<sub>*ij*</sub>}
on an rectilinear mesh {(log 𝜚)<sub>*i*</sub>} × {(log *ε*)<sub>*j*</sub>}, on an rectilinear mesh {(log 𝜚)<sub>*i*</sub>} × {(log *ε*)<sub>*j*</sub>},
*i*=0,n1-1 and *j*=0,n2-1, with n1 × n2 the number of mesh points. *i*=0,n1-1 and *j*=0,n2-1, with n1 × n2 the number of mesh points.
...@@ -1844,15 +1844,17 @@ An example can be found in the testproblem ...@@ -1844,15 +1844,17 @@ An example can be found in the testproblem
### User-defined background magnetic field ### User-defined background magnetic field
The module `sourceB0User.c` containing the function `sourceB0User()` The module `sourceB0User.c` containing the function `sourceB0User()`
serves as template for defining a background magnetic field, serves as template for defining a background magnetic field **B**<sub>0</sub>
$\mathbf{B}_0$, in the context of the magnetic field splitting formalism in the context of the magnetic field splitting formalism
(cf. [physics (cf. [physics guide](https://gitlab.aip.de/ziegler/NIRVANA/-/tree/master/doc/pdf/PhysicsGuide.pdf)).
guide](https://gitlab.aip.de/ziegler/NIRVANA/-/tree/master/doc/pdf/PhysicsGuide.pdf)). **B**<sub>0</sub> must be a time-independent, divergence-free potential field, i.e.,
$\mathbf{B}_0$ must be a time-independent, divergence-free potential
field, i.e., d**B**<sub>0</sub>/dt=0,
$$\partial_t\mathbf{B}_0=0$$,
$$\nabla\!\cdot\!{\mathbf{B}_0}=0$$ and ∇⋅**B**<sub>0</sub>=0
$$\nabla\!\times\!{\mathbf{B}_0}=0$$.
∇×**B**<sub>0</sub>=0.
In the call of `sourceB0User()` In the call of `sourceB0User()`
the function arguments are the pointer to the array `B0` of magnetic the function arguments are the pointer to the array `B0` of magnetic
field The function field The function
...@@ -1861,8 +1863,8 @@ field The function ...@@ -1861,8 +1863,8 @@ field The function
takes arguments `B0`, a pointer to a 3-element vector for the components takes arguments `B0`, a pointer to a 3-element vector for the components
of the magnetic field, and the spatial coordinates `x,y,z` of a point. of the magnetic field, and the spatial coordinates `x,y,z` of a point.
The user must define the components `B0[0]`=$B0_x$, `B0[1]`=$B0_y$ and The user must define the components `B0[0]`=*B*<sub>0x</sub>,
`B0[2]`=$B0_z$, respectively, `B0[1]`=*B*<sub>0y</sub> and `B0[2]`=*B*<sub>0z</sub>, respectively.
An example definition for a background field (a magnetic dipole field) An example definition for a background field (a magnetic dipole field)
can be found in testproblem `/nirvana/testproblems/MHD/problem30`. can be found in testproblem `/nirvana/testproblems/MHD/problem30`.
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