trixi-framework/Trixi.jl

Enhance Restarting Capabilities

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#2,316 opened on Mar 23, 2025

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enhancementgood first issuepossible student project

Description

Two features I often miss in restarting is

  • Restarting from different (lower) polynomial degrees. Use case would be a cheaper simulation to get somewhat physical fields and then enhance quality. Another use case would be an easier comparison of solutions with different polynomial degrees.
  • Restarting a hyperbolic-parabolic simulation from a (purely) hyperbolic simulation, i.e., computing the gradients from the solution. Certainly, in that case the solution does not correspond to the equations at hand, but might still be helpful. EDIT: Already possible, see PR #2452

Contributor guide

Tech stack
None
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Julia programming languagenumerical simulation conceptsTrixi.jl codebase structurepolynomial degree concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The issue is to implement restarting from a lower polynomial degree. Currently, restarting from a different polynomial degree is not supported. Look at the existing restarting mechanism in the codebase, particularly in src/ files. Review PR #2452 which partially addressed restarting from hyperbolic to parabolic. The implementation likely involves modifying solution loading and interpolation routines to handle different polynomial degrees. Check maintainer comments for additional guidance.