Constraint-preserving Sommerfeld conditions for the harmonic Einstein equations
The principle part of Einstein equations in the harmonic gauge consists of a constrained system of 10 curved space wave equations for the components of the space-time metric. A new formulation of constraint-preserving boundary conditions of the Sommerfeld-type for such systems has recently been proposed. We implement these boundary conditions in a nonlinear 3D evolution code and test their accuracy.
M.C. Babiuc, H-O. Kreiss, and J. Winicour. (2007) Constraint-preserving Sommerfeld conditions for the harmonic Einstein equations. Phys. Rev. D, 75(4):044002–044002(13).