Initial Data

Initial data for the $3+1$ variables is specified by the initial_data (3-metric and extrinsic curvature), initial_lapse (lapse), and initial_shift (shift) parameters. By default, ADMBase initialises the 3-metric and extrinsic curvature to Minkowski and the lapse to one. Initial data thorns override these defaults by extending the parameters. To see which initial data sets are available in your executable run for example

./cactus_<config> -o admbase::initial_data | grep Range

The CactusEinstein arrangement includes thorns providing initial data for various black hole combinations, perturbed black holes and linear gravitational waves.