Trixi.jl is a treebased numerical simulation framework for hyperbolic PDEs in Julia. We have rewritten Trixi.jl completely to make it more modular and Julian  we made the transition from “Trixi as a monolith” to “Trixi as a library” (search for PRs/commits/issues mentioning “Taal” in our repo). In particular, we got rid of TOML parameter files to set up simulations and replaced them by pure Julia code, an approach many people have asked for, e.g., @stillyslalom, @rveltz, and @antoinelevitt in the first announcement of Trixi and @PetrKryslUCSD on GitHub. You can find an example at examples/2d/elixir_advection_basic.jl
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On top of that, we made Trixi more modular to make better use of other Julia packages. In particular, you can now use all of the SciML ecosystem for time stepping. Thanks again to @ChrisRackauckas for reviewing our PRs to OrdinaryDiffEq.jl to make this work!
As a side effect, these changes allowed us to reduce the latency of Trixi significantly and to make further improvements, e.g., optimization of the AMR part and simplification of our multiphysics approach. Other changes include the addition of a 1D DGSEM solver, positivitypreserving limiters, and proper support for weaklyenforced boundary conditions.
Trixi’s features include (differences to v0.1/v0.2 highlighted):
 Hierarchical quadtree/octree grid with adaptive mesh refinement
 Native support for 1D, 2D, and 3D simulations
 Highorder accuracy in space in time
 Nodal discontinuous Galerkin spectral element methods
 Kinetic energypreserving and entropystable split forms
 Entropystable shock capturing
 Positivitypreserving limiting

Compatible with the SciML ecosystem for ordinary differential equations
 Explicit lowstorage RungeKutta time integration
 Strong stability preserving methods
 CFLbased and errorbased time step control
 Square/cubic domains with periodic and weaklyenforced boundary conditions
 Multiple governing equations:
 Compressible Euler equations
 Magnetohydrodynamics equations
 Hyperbolic diffusion equations for elliptic problems
 Scalar advection
 Multiphysics simulations
 Sharedmemory parallelization via multithreading
 Visualization of results with Juliaonly tools (Trixi2Img)
or ParaView/VisIt (Trixi2Vtk)