lehrenfeld shared a status by migoettingen
MI Göttingen
migoettingen@academiccloud.social

🔍 Infostand: Numerische Simulation physikalischer Systeme

Physikalische Systeme simulieren und optimieren: Wir machen den Vergleich zwischen numerischen Methoden und Experimenten.

⏲ Uhrzeit: 17:00-24:00 Uhr
🗓️ Datum: 21.06.2025

🧑‍🔬 Veranstalter: Institut für Numerische und Angewandte Mathematik (u.a. @lehrenfeld)
📍 Veranstaltungsort: Foyer, ZHG, Platz der Göttinger Sieben 5

#ndwGoeCountdown #ndwGoe #Goettingen #ZcampusGoe #theGoeCampus #uniGoettingen #Mathematik

June 20, 2025
lehrenfeld shared a status by migoettingen
MI Göttingen
migoettingen@academiccloud.social

🔍 Inverse Probleme - mit Mathematik das Unsichtbare sichtbar machen
Wir erklären interaktiv, wie inverse Probleme in Wissenschaft & Technik gelöst werden – am Beispiel der Computertomographie.

⏲ Uhrzeit: 17:00-24:00 Uhr
🗓️ Datum: 21.06.2025

🧑‍🔬 Veranstalter: Institut für Numerische und Angewandte Mathematik
📍 Veranstaltungsort: Foyer ZHG, Platz der Göttinger Sieben 5

#ndwGoeCountdown #ndwGoe #Goettingen #ZcampusGoe #theGoeCampus #uniGoettingen #Mathematik

June 18, 2025
lehrenfeld shared a status by arXiv_mathNA_bot
arXiv math.NA bot
arXiv_mathNA_bot@mastoxiv.page

Discretization Error Analysis of a High Order Unfitted Space-Time Method for moving domain problems

Fabian Heimann, Christoph Lehrenfeld, Janosch Preu{\ss}
https://arxiv.org/abs/2504.08608 https://arxiv.org/pdf/2504.08608 https://arxiv.org/html/2504.08608

arXiv:2504.08608v1 Announce Type: new
Abstract: We present a numerical analysis of a higher order unfitted space-time Finite Element method applied to a convection-diffusion model problem posed on a moving bulk domain. The method uses isoparametric space-time mappings for the geometry approximation of level set domains and has been presented and investigated computationally in [Heimann, Lehrenfeld, Preu{\ss}, SIAM J. Sci. Comp. 45(2), 2023, B139 - B165]. Recently, in [Heimann, Lehrenfeld, IMA J. Numer. Anal., 2025] error bounds for the geometry approximation have been proven. In this paper we prove stability and accuracy including the influence of the geometry approximation.

April 14, 2025
lehrenfeld shared a status by unigoettingen
Uni Göttingen
unigoettingen@academiccloud.social

Hallo Mastodon-Community! Ab heute berichten wir hier über die Uni Göttingen und freuen uns auf den Austausch. Wer ist auch noch hier?

Hello to everyone on Mastodon! You’ll find the University of Göttingen’s news here. We’re looking forward to the exchange! Who else is here?

January 16, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

Yesterday, we had our FEStokes-RePair game night.
It was fun. We experimented with the FEStokes-Repair Validator app and we even developed a Poker version of the game. #gameon #festokesrepair #FiniteElements

January 10, 2025
lehrenfeld shared a status by migoettingen
MI Göttingen
migoettingen@academiccloud.social

Wir wünschen einen unfallfreien Winterabend! ❄️☃️❄️

Kommt gut nach Hause!

January 09, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

To celebrate and share the fun, we’re hosting an online game night on January 9th at 6:30 PM (CET). Everyone is welcome to join and try the game – no prior knowledge required! 🃏 https://fe-nerd-games.github.io/FEStokesRePair/

January 01, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

In autumn, we got the first edition printed, and it became a gift several times during the holiday season.

You can get the card game here: https://www.printerstudio.de/sell/designs/fe-stokes-re-pair-skat90.html (in case you have recommendations for other card printers, let me know) or print it yourself: https://raw.githubusercontent.com/fe-nerd-games/FEStokesRePair/refs/heads/main/diy_festokesrepair.pdf

#FEStokes-RePair

January 01, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

Coming up with a "cheat sheet" that reveals which discretiations are working (and possibly achieve additional properties) was difficult and we are currently working on a small web app to explore this more interactively. #FEStokes-RePair

January 01, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

Stokes discretizations need compatible choices of velocity and pressure unknowns or stabilizations which are represented through cards in the game. Finding working combinations makes it fun for researchers and students in numerical analysis.

The rules can be downloaded on our homepage https://fe-nerd-games.github.io/FEStokesRePair/ . Alternatively, more conveniently, we also uploaded a NotebookLM-generated Podcast on the games rules that explain it (surprisingly?) well. Here is an excerpt of it.

January 01, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

✨ A small dream came true last year: In the past year, we developed our very own (nerd) card game: FEStokes-RePair! 🎉🃏

The game uses the finite element discretization of the Stokes equations as a metaphor.

For details see here: https://fe-nerd-games.github.io/FEStokesRePair/ (and the following thread)

#NumericalAnalysis
#MathGames
#EducationalGames
#FiniteElements
#FEStokes-RePair

January 01, 2025
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

Currently, I am on my way to the POEMS 2024 (polytopal element methods) workshop in Paris 🚆 and I thought that I should prepare a poem ✍️ as part of my presentation 🎞️ on our recent research work 💡 on Trefftz-like DG methods (which also come online as a preprint on arXiv today: https://arxiv.org/abs/2412.00806 ). Enjoy my recent draft 😎.

December 03, 2024
lehrenfeld shared a status by arXiv_mathNA_bot
arXiv math.NA bot
arXiv_mathNA_bot@mastoxiv.page

A unified framework for Trefftz-like discretization methods

Philip L. Lederer, Christoph Lehrenfeld, Paul Stocker, Igor Voulis
https://arxiv.org/abs/2412.00806 https://arxiv.org/pdf/2412.00806 https://arxiv.org/html/2412.00806

arXiv:2412.00806v1 Announce Type: new
Abstract: This paper presents a unifying framework for Trefftz-like methods, which allows the analysis and construction of discretization methods based on the decomposition into, and coupling of, local and global problems. We apply the framework to provide a comprehensive error analysis for the Embedded Trefftz discontinuous Galerkin method, for a wide range of second-order scalar elliptic partial differential equations and a scalar reaction-advection problem. We also analyze quasi-Trefftz methods with our framework and build bridges to other methods that are similar in virtue.

December 03, 2024
Christoph Lehrenfeld
lehrenfeld@academiccloud.social
Gezwungene Reime

Als Adventszeitgruß in die Runde krame ich ein altes Gedicht für Euch aus:

https://youtu.be/flvL75M5RWo

🌲🎄🌐

December 02, 2024
Christoph Lehrenfeld
lehrenfeld@academiccloud.social

@RomanBaum @mosterh1 wir werden viel mit gitlab/jupyter arbeiten, aber haben templates vorbereitet, sodass man kein Experte für gitlab/python/jupyter sein muss, um etwas mitzunehmen, hoffen wir.

September 23, 2024