Wednesday, 27 July 2011

Modelling of transient flows in tunnel fires

Our most recent paper on tunnel fires has just been published in the journal Computers and Fluids. The title is:

The paper applies a transient multiscale approach to model ventilation flows and fires in a long tunnel. It couples dynamically a Computational Fluid Dynamics solver with a simple 1D model, allowing for a more rational use of the computational resources without loss of accuracy.

Schematic of the multiscale model of the1.2 km tunnel from portal to portal and including 10 jet fans pairs. The CFD domain of the fire region contains temperature contours showing the fire plume.

After all the fundamentals of the coupling are discussed, the methodology is applied to study the unsteady flow interaction between a growing fire and a ramping-up ventilation system in a modern tunnel (7 m diameter, 1.2 km long). To the best of our knowledge, this is the first time than a growing fire and a growing ventilation are studied together. The results allow for simultaneous optimization of the ventilation and detection systems, and allows engineering answers to questions that could not be posed before by tunnel designers.

Longitudinal velocity field computed 180 s after fire ignition (60 s after ventilation activation) for three ventilation scenarios (3, 5 or 10 jet fan pairs respectively). Velocity values are expressed in m/s.

The work is a continuation of the collaboration between Politecnico di Torino and University of Edinburgh led by Dr Francesco Colella (the work is based on this 2010 thesis "Multiscale modelling of tunnel ventilation flows and fires").

NOTE: An earlier paper related to this received the 2010 Lloyd's Science of Risk Prize.

Tuesday, 19 July 2011

Despite the laws of thermodynamics that govern wildfires: NYT article

The NYT published last month a very interesting article on the use of computer modelling of wildfires to aid fire fighting decisions during the recent extreme fire behaviour suffered in Arizona, USA.

The full article is Fighting Wildfires With Computers and Intuition. Some excerpts that I found interesting are:
Fire behaviorists work alongside meteorologists, given that the weather, especially wind patterns, plays a pivotal role in how a wildfire grows. The topography is also important because fires burn differently depending on whether they are going up a steep slope, across a valley or through a developed area. Then there are what firefighters call the fuels, which are the vegetation and other materials that give fires energy as they move along.
The fires that Arizona has experienced, some surging forward faster than expected, are testing the mathematical models that behavior specialists use. Tom Zimmerman, a fire behavior expert at the National Interagency Fire Center for the United Forest Service in Boise, Idaho, said that the Wallow Fire had on occasion advanced more quickly than the models predicted. “We use each fire to verify the models and make them more accurate,” he said.
Despite learning the laws of thermodynamics that govern fires, behavior specialists say there is still plenty of unpredictability to each blaze, which requires them to draw on their long experience. Fires can produce their own weather patterns, for instance, which can then end up altering the course of the fires.

Sunday, 10 July 2011

Smouldering mega fires are back in Russia: burning peat

Remember the Russian wildfires last summer that choked the city of Moscow and other regions? These were smouldering mega fires burning for several weeks and caused by the slow burning of dry peatlands. See here for an introduction to smouldering combustion.

Unfortunately, they are back this summer. Last week, they were several flaming fires burning in the region of Moscow. After flames were extinguished, the peat was seen to smoulder. Given the pollution, environmental and climate disaster that the smouldering mega fires brought last summer, the worry is that they might burn for months in 2011 as well. Given the extreme difficulty of suppressing smouldering fires when these have already grown out of proportions, the Fire Service is afraid that the fate might be in the hand of the rain.

In the meantime, Greenpeace reported about 20 peat fires in Russia.

PD: There are currently smouldering mega fire burning in North Carolina, Georgia and Indonesia.

Monday, 4 July 2011

Call for papers: Fire Technology special issue on WTC Collapse

Fire Technology, the journal of the National Fire Protection Association published by Springer, is preparing an issue on the 2001 fire and collapse of World Trade Center.

The purpose is to collect research, forensic and engineering output of the highest scholarly standards synthesized in the 10 years passed since the event.

Multidisciplinary and international contributions are especially encouraged. Topics of interests include: WTC 1, 2, 5 and 7, the crash, fires, structural response, collapse, forensic conclusions, experiments, modelling, Fire and Rescue intervention, human behaviour, building design, post-collapse fires and recovery, previous attacks on WTC and related subjects.

Submissions will be accepted until 11th Nov 2011 at: (choose article type "World Trace Center") .

The call for papers flyer can do downloaded here. Please spread the word, we are looking for a wide range of high quality submissions.

For further information, contact the Associate Editor of this special issue: Dr Guillermo Rein, The University of Edinburgh.

A New York City fireman calls for 10 more rescue workers to make their way into the rubble of the World Trade Center. Photo form Wikipedia, United States Navy ID 010914-N-3995K-01