---
title: "Francis H. Harlow"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Francis H. Harlow"
aliases: ["F.H. Harlow","Frank Harlow"]
first_seen: "2026-07-09T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["particle-in-cell method","Los Alamos Scientific Laboratory","J.U. Brackbill","Material Point Method","Cold War computational physics"]
seek_code_commit: "17d9798"
---


Physicist at the Los Alamos Scientific Laboratory who invented the particle-in-cell
(PIC) method around 1957–1962, a hybrid Eulerian/Lagrangian scheme for simulating
compressible fluids undergoing large deformation on early high-speed computers. Matters
to this vault as the root of a numerical lineage it has now traced across three
generations: PIC ([[claim-pic-method-born-at-los-alamos-for-hydrodynamics]]) extended
into [[entity-j-u-brackbill|J.U. Brackbill]]'s FLIP (1986), which
[[entity-deborah-sulsky|Deborah Sulsky]], Zhen Chen, and Howard Schreyer reformulated
into the Material Point Method for Sandia-funded solid-mechanics work
([[claim-material-point-method-1993-sandia-funded-penetration-mechanics]]), which
twenty years later became the physics engine for Disney's *Frozen* snow
([[claim-frozen-snow-ran-on-material-point-method-matterhorn]]). Both MPM founding
papers cite Harlow's original PIC report as their direct methodological ancestor, ahead
of even their own co-authors' prior work.

## References
- [[claim-pic-method-born-at-los-alamos-for-hydrodynamics]]
- [[claim-material-point-method-1993-sandia-funded-penetration-mechanics]]
- [[claim-mpm-1994-paper-acknowledges-sandia-and-nsf-cofunding]]
- [[claim-mpm-founding-papers-motivated-by-broad-problem-class]]
- [[claim-frozen-snow-ran-on-material-point-method-matterhorn]]
- Captures: 10-inbox/raw/2026-07-09-hop-weapons-labs-to-frozen-snow.md, 10-inbox/raw/2026-08-21-was-the-material-point-method-actually-developed-for.md