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diff --git a/doc/documentation.tex b/doc/documentation.tex index cdf33f7..601a123 100644 --- a/doc/documentation.tex +++ b/doc/documentation.tex @@ -170,7 +170,42 @@ In this way the initiation of the primitive variables, methods to recover the co variables, and basic atmosphere handling can be implemented in different thorns while allowing a central access point for analysis thorns. -\subsection{Acknowledgments} +\section{Units} + +HydroBase uses a specific set of units, so that there are no +misunderstandings between thorns. These units are derived from the +conventions +\begin{eqnarray} + M = M_\mathrm{sun} &;& c = G = 1 +\end{eqnarray} +which are commonly used in astrophysics and in relativity. + +We assume the following definitions and constants of nature: +\begin{eqnarray} + c & = & 299792458\, \mathrm{m/s} + \\ + G & = & 6.67428\cdot 10^{-11}\, \mathrm{m^3/kg/s^2} + \\ + \mu_0 & = & 4 \pi 10^{-7}\, \mathrm{N/A^2} + \\ + \epsilon_0 & = & \frac{1}{\mu_0 c^2} + \\ + M_\mathrm{sun} & = & 1.98892\cdot10^{30}\, \mathrm{kg} +\end{eqnarray} + +This corresponds to the following units for mass, length, time, and +magnetic field: +\begin{eqnarray} + [M] & = & M_\mathrm{sun} + \\{} + [L] & = & [M]\; G/c^2 + \\{} + [T] & = & [L]\; / c + \\{} + [B] & = & 1/[L]\; / \sqrt{\epsilon_0 G / c^2} +\end{eqnarray} + +\section{Acknowledgments} This thorn was produced by Tanja Bode, Roland Haas, Frank Löffler, and Erik Schnetter. |