The Computing Division Technical Meetings are a platform for

  • presenting Pinboard papers under review for journal or conference publication,
  • inviting speakers who are current or prospective UKAEA collaborators at external organisations,
  • presenting work done in PhD projects funded by or co-supervised by UKAEA,
  • presenting work done during summer placements or other secondments to UKAEA.

 

If you would like to invite a speaker on a topic that would be of interest to one or more Units within the Computing Division, but is not currently collaborating on a UKAEA project, please consider nominating them for a Computing Division Cross-Disciplinary Seminar.

These meetings are normally recorded. Recordings of past meetings can be found here:

CD Technical Meetings Archive on UKAEA Sharepoint

CD Technical Meeting (NM1): Time-Parallel Algorithms for Chaotic Systems

Europe/London
Giancarlo Antonucci (Plasma Simulation)
Description

Numerical Methods

Abstract

Supercomputers today can have millions of cores, but traditional methods for solving differential equations can only use space parallelisation effectively up to a few thousand cores. Parallelisation across time appears to be a promising way to provide more parallelism. Chaos makes this hard: small errors grow exponentially, causing nearby paths to diverge. In this talk, we'll show a new framework for understanding how time-parallel algorithms work on nonlinear problems. Building on this, we'll present the moving-window (MoWi) algorithm, which splits long simulations into shorter, overlapping windows. Within each window, we use time parallelisation, but between windows we carefully control errors using a weighted measure that accounts for chaos. This lets MoWi sample paths from the system's attractor while keeping the right statistics and achieving parallel speedup. We'll outline the conditions under which this method can outperform standard implementations of time-parallel methods like Parareal for long simulations of turbulent systems, and present adaptive strategies that change parameters based on local behaviour.

Participants
  • Jony Castagna
    • 14:00 14:45
      Talk 45m
      Speaker: Giancarlo Antonucci (Plasma Simulation)
    • 14:45 15:00
      Q&A 15m
      Speaker: Giancarlo Antonucci (Plasma Simulation)