| ... | ... | @@ -1445,9 +1445,6 @@ below category PHYSICS SPECIFICATIONS. |
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### User-defined coefficient for ambipolar diffusion
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The module `APdiffusionCoeffUser.c` serves as template for a
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user-defined ambipolar diffusion coefficient.
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Ambipolar diffusion enters the induction equation and energy equation as
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a field contribution given by
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| ... | ... | @@ -1455,8 +1452,7 @@ a field contribution given by |
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where *η*<sub>*AD*</sub> in units \[V⋅m⋅A<sup>−1</sup>⋅T<sup>−2</sup>\]
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denotes the ambipolar diffusion coefficient.
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The prefactor* *η*<sub>*AD*</sub>/*μ* has units
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The prefactor *η*<sub>*AD*</sub>/*μ* has units
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m<sup>2</sup>⋅s<sup>−1</sup>⋅T<sup>−2</sup>.
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A user-defined coefficients, *η*<sub>*AD*</sub>,
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| ... | ... | @@ -1490,8 +1486,8 @@ found in testproblem `/nirvana/testproblems/APDIFF/problem1`. |
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### User-defined body force
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The module `forceUser.c` serves as template for a user-defined
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*specific* body force $\mathbf{f}$ (force per mass in units
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N$\cdot$kg$^{-1}$). The body force enters the momentum equation and
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*specific* body force **f** (force per mass in units N⋅kg<sup>−1</sup>).
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The body force enters the momentum equation and
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energy equation as source term.
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A user body force has to be defined in the function
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| ... | ... | @@ -1526,12 +1522,13 @@ be found in testproblem `/nirvana/testproblems/MHD/problem21`. |
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The modules `sourceCoolingUser.c` and `sourceHeatingUser.c` serve as
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templates for coding a user-defined cooling function,
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$L_\mathrm{cool}\le 0$, and heating function, $L_\mathrm{heat}\ge 0$,
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respectively. Both functions are allowed to depend on temperature $T$
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and density $\varrho$. The net heatloss, i.e. the sum
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$L_\mathrm{cool}(T,\varrho)+L_\mathrm{heat}(T,\varrho)$, enters as
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source term in the energy equation. $L_\mathrm{cool}$ and
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$L_\mathrm{heat}$ are measured in units J$\cdot$s$^{-1}\cdot$m$^{-3}$.
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*L*<sub>*cool*</sub>≤0, and heating function, *L*<sub>*heat*</sub>≥0,
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respectively. Both functions are allowed to depend on temperature
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*T* and density 𝜚. The net heatloss, i.e. the sum
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*L*<sub>*cool*</sub>(*T*,𝜚)+*L*<sub>*heat*</sub>(*T*,𝜚), enters as
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source term in the energy equation.
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*L*<sub>*cool*</sub> and *L*<sub>*heat*</sub> are measured
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in units J⋅s<sup>−1</sup>⋅m<sup>−3</sup>.
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User-defined cooling/heating rates are to be defined in the functions
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| ... | ... | @@ -1541,11 +1538,10 @@ User-defined cooling/heating rates are to be defined in the functions |
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taking arguments `T`, the temperature, `rho`, the gas density, the
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pointer `deriv`, a flag to tell the calling function whether the user
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provides the derivatives $\partial L_\mathrm{cool}\partial\varrho$,
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$\partial L_\mathrm{cool}\partial T$ to be stored in the 2-element
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vector `dfc[0], dfc[1]` and the derivatives
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$\partial L_\mathrm{heat}\partial\varrho$,
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$\partial L_\mathrm{heat}\partial T$ to be stored in the 2-element
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provides the derivatives ∂*L*<sub>*cool*</sub>/∂𝜚,
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∂*L*<sub>*cool*</sub>/∂*T* to be stored in the 2-element
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vector `dfc[0], dfc[1]` and the derivatives ∂*L*<sub>*heat*</sub>/∂𝜚,
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∂*L*<sub>*heat*</sub>/∂*T* to be stored in the 2-element
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vector `dfh[0], dfh[1]`. The default value is preset to `deriv=YES` in
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both functions. The user may avoid to explicitely calculating
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derivatives by setting `deriv=NO`. Then, derivatives are computed by the
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