A wind-driven ember shower is a key wildfire exposures a building can face, but we have not yet fully understood or accounted for them in making our communities wildfire resilient. Today we sit down with Samuel L. Manzello of Tohoku University and Reax Engineering to unpack how in the last 20 years the firebrand science went from not being able to characterize the features of them well to being able to procur controlled experiments and standardized generators that can actually shape building codes and product design.

We dig into what firebrands really are, why vegetation embers and structure-generated embers behave differently, and why lab tests with single particles often fail to explain the ignitions seen after major WUI disasters. From there, we follow the chain reaction that led to the Dragon firebrand generator: the need for wind, the lack of suitable facilities, and the breakthrough of creating a continuously feedable device that can produce repeatable firebrand showers. Samuel explains how airflow settings can shift firebrands from glowing to flaming, and why that control is essential for meaningful wildfire exposure testing.

The second half moves into standardization and real-world impact. Samuel breaks down ISO TC 92 and the work of the IAFSS LOFBE group on large outdoor fires in the built environment, including why the "Baby Dragon" became an ISO methodology and what it unlocks next: better roof tests, vent penetration tests, facade and opening vulnerabilities, and more consistent ways to compare hazards across regions and vegetation types. If you care about wildfire resilience, WUI fire safety, ember intrusion, and the future of practical standards, this conversation maps the path forward.

As promised, here are some links:

• The world is burning: What exactly are firebrands and why should anyone care?
• Progress in creating international standards
• Experimentally producing various firebrands
• NIST - Dragon firebrand generator (2014)
• Samuel's classic paper from 2006 - on ignition of mulch with firebrands

But there is much, much more in the literature on the firebrands! I recommend going to Scopus or Google Scholar and looking for Samuel's record there: https://scholar.google.com/citations?user=4oAvxXMAAAAJ&hl=pl&oi=ao

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

Wildland-Urban Interface fires are a class of fires that deserves own models, own studies and a lot of research focus. This is what I discuss today with prof. Arnaud Trouvé from the University of Maryland, shortly before he has given his plenary talk at the recent Combustion Symposium in Kyoto. In this interview, Arnaud explains what makes wildland urban interface (WUI) fires and urban conflagrations so hard to predict, also with a focus on the combustion phenomena.

Arnaud is interested in how the fires spread from the wildlife into the urban areas, and how to model this spread. The state of the art models for fire spread are lacking in here, due to how they perceive a fire front as a "line", whereas in cities we are looking at collection of compartment-household fires that may last for hours, and create a burning area kilometre wide. Therefore, we need new modelling approaches, and we need them at three scales - the scale of vulnerabilities of a parcel, a parcel-to-parcel setups and whole community scales.

To improve the state of the art, he breaks the problem into the scales that matter: indoor fire dynamics (where CFD can estimate structure burning), parcel-level exposure (where fire penetration is the missing link), and community-scale fire spread (where reduced order models dominate because fuel and building maps are often coarse). We dig into the practical modeling mechanics behind WUI simulators: 2D spread on gridded maps, simplified radiation and flame shape models, probabilistic firebrand transport, and the limits of one-way coupling where wind is prescribed but not influenced by the fire.

We also discuss an important bottleneck: the data. Satellite observations often arrive with poor temporal resolution, and controlled full-scale experiments are rare, which makes validation and scenario selection painfully uncertain. We also discuss why windows and near-structure fuels can be a universal pathway for loss, and why the field needs stronger shared infrastructure and collaboration to move faster.

Congratulations on your plenary talk and thank you Arnaud for representing the fire community at the Combustion Symposium. Once Arnaud's plenary paper is published, I will update the show notes with a link!

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

In todays episode of fire fundamentals we talk with Professor Elizabeth Weckman from University of Waterloo about advanced optical diagnostics that let fire researchers read temperature, chemistry, soot, and velocity from light without relying only on probes. We break down what cameras, infrared imaging, spectroscopy, lasers, and PIV can reveal, plus the calibration and interpretation pitfalls that can quietly ruin your data.

Things covered in this episode:
• why optical diagnostics are “non-intrusive” in practice and where they still perturb the flow
• limits of probe-based measurements in fire including spatial resolution and radiation errors
• using basic photography and video as a first diagnostic and as a planning tool
• calibration habits for cameras and why cheap, robust cameras are often a better choice for a fire laboratory
• infrared thermography for surface heating plus emissivity problems and practical coatings
• Schlieren imaging for density and temperature gradients and what it can and cannot imply
• point vs planar vs line-of-sight vs tomographic measurements and how “smearing” happens
• FTIR and absorption spectroscopy for pyrolysis gases, emissions, and toxic species
• chemiluminescence and laser-induced fluorescence to mark combustion and flame fronts
• Raman and CARS for temperature and concentration and why they are technically demanding
• soot diagnostics from light extinction to laser-induced incandescence and aging effects
• PIV basics, seeding challenges in fire, and what velocity fields unlock for validation

The episode is best enjoyed along Beth's paper from the IAFSS: Unravelling the mysteries of fire

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.