Trixi.jl Model Coupling Examples

SNuBIC-facing wrapper repository for selected Trixi.jl coupling and mesh-view developments by Simon Candelaresi.

This repository collects minimal examples, setup helpers, and citation metadata for developments related to p4est mesh-view coupling in Trixi.jl.

Scope

The repository covers the following upstream Trixi.jl pull requests by Simon Candelaresi:

PR	Title	State	Opened	Upstream branch
#2456	Enhanced p4est mesh view coupling	open	2025-06-26	sc/p4est-view-coupled-enhanced
#2598	WIP: Sc/p4est view coupled hanging nodes	open	2025-10-09	sc/p4est-view-coupled-hanging-nodes

It also documents the merged precursor developments in the same line:

PR	Title	State	Opened	Merged
#2366	Sc/p4est view coupled	merged	2025-04-17	2026-03-04
#2110	WIP: Sc/Enhanced p4est mesh views	merged	2024-10-14	2025-04-16

A detailed component-to-PR mapping is in docs/upstream-prs.md.

Relation to SNuBIC

The developments covered here concern bulk- and interface-coupling of heterogeneous models and structure-preserving numerical methods, the theme of the DFG research unit SNuBIC (FOR 5409).

Contents

• Setup helpers that add the appropriate Trixi.jl revision into a local Julia environment.
• Minimal example drivers exercising the coupling and mesh-view feature paths.
• Lightweight smoke tests.
• Citation metadata (CITATION.cff, .zenodo.json) and a Zenodo DOI placeholder.

Trixi.jl is not vendored; the setup scripts pin upstream revisions (exact SHAs, with branch fallbacks) for reproducibility.

Requirements

• Julia 1.10 or newer.
• A C toolchain is not required: P4est_jll is provided as a Julia artifact by Trixi.jl's dependencies.

Quick start

All setup scripts activate this project (--project=.) and add the appropriate Trixi.jl revision into the environment.

Base setup (upstream main Trixi.jl)

julia --project=. scripts/setup_base.jl

Setup for the PR #2456 path (enhanced multi-variable coupling)

julia --project=. scripts/setup_pr2456.jl

Setup for the PR #2598 path (hanging / non-conforming nodes)

julia --project=. scripts/setup_pr2598.jl

Each PR setup script pins both a branch name and the exact commit SHA. If a SHA becomes unavailable (e.g. after a force-push upstream), edit the script to use the branch name only. The pinned revisions are:

Path	Upstream ref	Pinned SHA
base	main	(tracks upstream main)
#2456	sc/p4est-view-coupled-enhanced	c5969fad14d80d1a6c08e44c5d49cf94182ec8eb
#2598	sc/p4est-view-coupled-hanging-nodes	159d9c2c115a975d51bc4997e854014b40e37e7a

Examples

• examples/run_coupled_p4est_minimal.jl — minimal single-variable coupled p4est mesh-view advection setup, following the merged path around PR #2366.
• examples/run_mesh_view_multivar.jl — coupling of systems that use more than one variable across p4est mesh views (PR #2456).
• examples/run_hanging_nodes_placeholder.jl — exploratory non-conforming / hanging-node coupling (PR #2598).

Where an upstream elixir exists for a given feature path, the example locates and runs it (via trixi_include, with maxiters limiting the run to a few timesteps) rather than re-implementing it.

Smoke tests

The repository contains lightweight smoke tests:

julia --project=. scripts/smoke_test_base.jl     # instantiate + import Trixi
julia --project=. scripts/smoke_test_pr2456.jl   # load env + reach example stage
julia --project=. scripts/smoke_test_pr2598.jl   # load env + reach example stage

The base setup and import smoke test run on Julia 1.10 against upstream Trixi.jl. The run_coupled_p4est_minimal.jl example steps the coupled SemidiscretizationCoupledP4est solver (merged PR #2366 path) at maxiters = 3. The PR #2456 and #2598 paths require their respective setup scripts (open branches).

Citation and DOI

Zenodo DOI:

Suggested citation text (see also CITATION.cff):

Candelaresi, S., Torrilhon, M., Schlottke-Lakemper, M. (2026). Trixi.jl Model Coupling Examples (Version 0.1.0) [Software]. https://github.com/SNuBIC/trixi-model-coupling-examples

Acknowledgement

The upstream coupling and mesh-view developments covered here are due primarily to Simon Candelaresi within the Trixi.jl ecosystem. Trixi.jl is developed by the trixi-framework community and is licensed under the MIT license; this repository is licensed under BSD-3-Clause (see LICENSE).