Speaker: Kyle T. Mandli, NSF National Center for Atmospheric Research, Boulder, CO, USA

Time : 15:00 - 16:00 CEST (Rome/Paris)

Hosted at: SISSA, International School of Advanced Studies, Trieste, Italy

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Organizers : Pavan Pranjivan Mehta* (pavan.mehta@sissa.it) and Arran Fernandez** (arran.fernandez@emu.edu.tr)

* SISSA, International School of Advanced Studies, Italy

** Eastern Mediterranean University, Northern Cyprus

Keywords: finite volume methods, hyperbolic PDEs, Riemann solvers, coastal hazards, open source software

Abstract: Clawpack (Conservation Laws Package) [1, 5] is an open source ecosystem for solving hyperbolic systems of PDEs using high-resolution finite volume methods [4], in continuous development since 1994. The framework is built around a single organizing abstraction, the Riemann solver, which encapsulates the physics of a given system and allows the core wave-propagation algorithms, adaptive mesh refinement, and parallel infrastructure to remain agnostic to the application. This design has enabled a family of related solvers, including AMRClaw for patch-based adaptive refinement, GeoClaw [3] for geophysical shallow flows such as tsunamis and storm surge, and PyClaw [2], which exposes the same algorithms through a Python interface with distributed parallelism via PETSc.

This talk will survey the Clawpack ecosystem from the perspective of open source mathematical software: the underlying wave-propagation algorithms, the layered Fortran/Python architecture, and, in particular, the community development model and governance that have sustained the project across three decades, from contribution and review practices to the social challenges of maintaining research software as shared infrastructure. I will also discuss the practical entry points for new users and developers, from tutorials to writing custom Riemann solvers and source terms, which is the natural route by which new physics, including nonlocal operators handled through approaches such as operator splitting, can be incorporated. I will close with lessons learned, technical and social, and some thoughts on where community-developed mathematical software goes from here.

Biography: Kyle Mandli is a Scientist IV at the NSF National Center for Atmospheric Research (NSF NCAR) in the CGD Lab. Before NCAR, he was a research scientist at the Flatiron Institute, faculty in the Department of Applied Physics and Applied Mathematics at Columbia University, and a postdoc at the University of Texas at Austin. He received his Ph.D. in applied mathematics from the University of Washington in 2011, studying finite volume methods for multi-layered shallow flows. His research spans the computational and analytical aspects of geophysical shallow mass flows, including storm surge, tsunamis, and coastal flooding, along with adaptive mesh refinement, accelerator computing, and scientific software development practices. He is a lead developer of Clawpack and GeoClaw.

Bibliography

[1]   K. T. Mandli, A. J. Ahmadia, M. Berger, D. Calhoun, D. L. George, Y. Hadjimichael, D. I. Ketcheson, G. I. Lemoine, R. J. LeVeque: “Clawpack: building an open source ecosystem for solving hyperbolic PDEs”. PeerJ Computer Science 2:e68 (2016). https://doi.org/10.7717/peerj-cs.68
[2] D. I. Ketcheson, K. T. Mandli, A. J. Ahmadia, A. Alghamdi, M. Quezada de Luna, M. Parsani, M. G. Knepley, M. Emmett: “PyClaw: accessible, extensible, scalable tools for wave propagation problems”. SIAM Journal on Scientific Computing 34(4), pp. C210–C231 (2012). https://doi.org/10.1137/110856976
[3] M. J. Berger, D. L. George, R. J. LeVeque, K. T. Mandli: “The GeoClaw software for depth-averaged flows with adaptive refinement”. Advances in Water Resources 34(9), pp. 1195–1206 (2011). https://doi.org/10.1016/j.advwatres.2011.02.016
[4] R. J. LeVeque: Finite Volume Methods for Hyperbolic Problems. Cambridge Texts in Applied Mathematics, Cambridge University Press (2002). https://doi.org/10.1017/CBO9780511791253
[5] Website. “Clawpack”: https://www.clawpack.org (2026)