Llama Multi-Block Infrastructure

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The Llama code is a 3-dimensional multiblock infrastructure with adaptive mesh-refinement for Cactus based on Carpet. It provides different patch systems that cover the simulation domain by a set of overlapping patches. Each of these patches has local cooordinates with a well-defined relation to global Cartesian coordinates. However, all computations are carried out using a global Cartesian tensor basis such that complicated tensor transformations between patch systems can be avoided. Information between the different patches is communicated via interpolation in the overlap zones.

The main field of application is currently numerical relativity, and especially the full non-linear 3-dimensional evolution of binary black hole mergers, stellar core-collapse and computation of the associated gravitational-wave signatures.

With topologically spherical grids in the wave-zone, it is possible to resolve the gravitational waves with high accuracy, while at the same time employing Cartesian adaptive mesh refinement grids around the black holes to provide a well established discretized representation of the strong field region.