# AmrCore Source Code

In this Chapter we give an overview of functionality contained in the amrex/Src/AmrCore source code. This directory contains source code for the following:

• Storing information about the grid layout and processor distribution mapping at each level of refinement.

• Functions to create grids at different levels of refinement, including tagging operations.

• Operations on data at different levels of refinement, such as interpolation and restriction operators.

• Flux registers used to store and manipulate fluxes at coarse-fine interfaces.

• Particle support for AMR (see Particles).

There is another source directory, amrex/Src/Amr/, which contains additional classes used to manage the time-stepping for AMR simulations. However, it is possible to build a fully adaptive, subcycling-in-time simulation code without these additional classes.

In this Chapter, we restrict our use to the amrex/Src/AmrCore source code and present a tutorial that performs an adaptive, subcycling-in-time simulation of the advection equation for a passively advected scalar. The accompanying tutorial code is available in amrex-tutorials/ExampleCodes/Amr/Advection_AmrCore with build/run directory Exec/SingleVortex. In this example, the velocity field is a specified function of space and time, such that an initial Gaussian profile is displaced but returns to its original configuration at the final time. The boundary conditions are periodic and we use a refinement ratio of $$r=2$$ between each AMR level. The results of the simulation in two-dimensions are depicted in the Table showing the SingleVortex Tutorial.