Architecture Commons^™

Tricritical Point As A Crossover Between Type-Is And Type-Iis Bifurcations, Prabakaran Rajamanickam, Joel Daou

Progress in Scale Modeling, an International Journal

A tricritical point as a crossover between (stationary finite-wavelength) type-I_s and (stationary longwave) type-II_s bifurcations is identified in the study of diffusive-thermal (Turing) instability of flames propagating in a Hele-Shaw channel in a direction transverse to a shear flow. Three regimes exhibiting different scaling laws are identified in the neighbourhood of the tricritical point. For these three regimes, sixth-order partial differential equations are obtained governing the weakly nonlinear evolution of unstable solutions near the onset of instability. These sixth-order PDES may be regarded as the substitute for the classical fourth-order Kuramoto­­­­­­–­­Sivashinsky equation which is not applicable near the …

Scale Model Experiments Of Toxic Gas Production From The Combustion Of Polymers When Applied With Different Droplet Sizes Of Water Mist, Nicharee Thinnakornsutubutr, Masayuki Mizuno, Kazunori Kuwana

Progress in Scale Modeling, an International Journal

This research experimentally investigated the combustion of polymeric materials with water mist application in an enclosure, with an emphasis on the production of toxic gases. Two different diameters, ~100 and ~260 μm, were tested. The experimental conditions were determined based on Froude similarity laws for low drop Reynolds number conditions. Droplets and polymers’ physical and chemical properties influence the burning/extinguishing behavior and toxic-gas evolution. In general, larger droplets can extinguish a fire in a shorter time, and toxic gas concentrations in a test chamber decreased more rapidly. However, the large droplets tended to cause the flame expansion phenomenon for thermoplastics …

A Simplified Model For The Intermediate Structure Of Strong Fire Whirls, Forman A. Williams

Progress in Scale Modeling, an International Journal

A model is described for the overall structure of intense fire whirls, based on a spatially evolving vortex, with circulation enhancement driven by the axial acceleration of low-density gas in the core through the axial pressure gradient. The axial acceleration increases the entrainment rate into the core which, through mass conservation, increases the circulation if the angle between the tangential and radial velocity components remains fixed. The two-zone model employs general balance equations for regions inside and outside a cylinder of fixed radius, each inviscid, the inside region being presumed to have a constant density small compared with the (constant) …

Reduced-Scale Experiments And Numerical Simulations Of Informal Settlement Dwelling Fires, Vigneshwaran Narayanan, Antonio Cicicone, Ayden D. Botha, Richard Shaun Walls

Progress in Scale Modeling, an International Journal

Informal settlement dwellings (ISDs) house approximately one billion people in the developing world and this number is expected to double by the year 2030. Contemporary research on ISD fires has focused on understanding the fire dynamics within individual dwellings (micro-scale) and fire spread in settlements consisting of multiple dwellings (macro-scale). This paper aims to do two primary things: investigate if scaling methods that were derived for compartments with thermally thick boundaries can be applied to ISDs (compartments with thermally thin boundaries), and if they can adequately represent the most important phenomena associated with full-scale ISD fires; and demonstrate Fire Dynamics …

A Global Survey Of Infection Control And Mitigation Measures For Combating The Transmission Of Covid-19 Pandemic In Buildings Under Facilities Management Services, Hadi Sarvari, Zhen Chen, Daniel W. M. Chan, Ellyn A. Lester, Nordin Yahaya, Hala Nassereddine, Aynaz Lotfata

Civil Engineering Faculty Publications

Facilities management along with health care are two important aspects in controlling the spread of infectious diseases with regard to controlling the outbreak of global COVID-19 pandemic. Hence, with the increasing outbreak of COVID-19 pandemic, the importance of examining the relationship between the built environment and the outbreak of infectious diseases has become more significant. The aim of the research described in this article is to develop effective infection control and mitigation measures to prevent the transmission of COVID-19 pandemic in the built environment. This study seeks to answer the question of how the facilities management industry can help reduce …

Propositions For A Resilient, Post-Covid-19 Future For The Aec Industry, Hala Nassereddine, Kyung Wook Seo, Zofia K. Rybkowski, Christian Schranz, Harald Urban

Civil Engineering Faculty Publications

The coronavirus outbreak has challenged and continues to challenge every aspect of the supply chain within the AEC industry, forcing stakeholders to cope with increasing uncertainties and continuous change. The notion of resilience is especially salient now. While the need for the AEC industry to focus on resilience has been highlighted in recent articles, there is a need for a comprehensive discussion on what resilience means for the AEC industry and how companies can create built-in resilience. This paper takes the form of a high-level overview of where the industry is headed and aims to establish eleven propositions for a …

Open-Field Scale-Model Experiments Of Fire Whirls Over L-Shaped Line Fires, Yuto Iga, Kazunori Kuwana, Kozo Sekimoto, Yuji Nakamura

Progress in Scale Modeling, an International Journal

This paper presents the results of open-field scale-model experiments of fire-whirl formation over line fires. L-shaped line fires were burned in crosswinds, and the processes of fire-whirl formation were observed. The flame height was measured using an image-processing technique, while two-dimensional velocity components were measured at two different locations using ultrasonic anemometers. Two tests were selected for comparison: test A, in which intense fire whirls repeatedly formed, and test B, in which no whirls were observed. In test A, the wind flow was bent by the fire plume, creating swirling flows near the burning area, thereby forming fire whirls. On …

Effect Of Reduced Plume Entrainment On The Burning Rate Of Porous Fuel Beds, Sara Mcallister

Progress in Scale Modeling, an International Journal

Large outdoor fires often exhibit unexpected fire behavior, particularly compared with much smaller fires. Understanding the difference between large- and small-scale fires is of importance for both fire behavior predictions and safety. Large fires are often characterized by very tall plumes that can extend to the stratosphere. Particularly as the actively burning area increases, plumes in large-scale fires likely entrain relatively little and may act in a similar fashion to a chimney. To explore the possible changes in burning rate due to the chimney effect, experiments were conducted with wood cribs burned with a chimney of variable height. The burning …

Extinguishment Of Diffusion Flames Formed Over A Porous Plate Burner Using Rubber Balloons Filled With Inert Gases, Hiroyuki Torikai, Shinya Kudo

Progress in Scale Modeling, an International Journal

We have proposed an inert gas, rubber-balloon extinguishing method which might increase the effectiveness of extinguishing flames and decreasing the amounts of agents needed for fire suppression. Hence, extinguishing experiments have been performed to further clarify possible extinguishing characteristics, mechanisms and scaling effects of this method. Carbon dioxide, nitrogen, argon and helium gases were used as the extinguishing agents. Methane-air and propane-air diffusion flames were formed on two different diameter, round porous plate burner and used as the targets for extinguishment. The extinguishing probabilities were measured, and the extinguishing processes were observed with a high-speed camera. As a result, an …

Data-Driven Tools Guided By First-Principles For Scale Modeling, Sadegh Poozesh

Progress in Scale Modeling, an International Journal

For decades, traditional scale-modeling techniques have been relying on first-principles models (FPMs). FPMs have been used to find non-dimensional numbers (PIs) and identify normalized underlying forces and energies behind the phenomenon in focus. The two main challenges with FPM-based PIs extraction are finding the relevant PIs and proper correlations between PIs. The emergence and surge of data-driven modeling (DDM) provide a new opportunity to leverage experimental data in model development across scales/plants. In this paper, first, the two mentioned issues in PIs development will be elaborated to reveal the gap, and second, a new insight into scale modeling and similarity …

Cracking During Flame Spread Over Pyrolyzing Solids, Yen Nguyen, Indrek S. Wichman, Thomas J. Pence

Progress in Scale Modeling, an International Journal

A theoretical and numerical model for the degradation of solid materials in combustion is developed. As solid materials are heated by the flame, they undergo an internal thermo- chemical breakdown process known as pyrolysis. As the pyrolysis front propagates into the sample, a charring layer is left behind which contains voids, fractures and defects. Cracks propagate to release tensile stresses accumulated when the sample is losing mass. The crack front may precede the pyrolysis front into the sample. Crack patterns and fracture behaviors vary depending on material properties and heating level and distribution. Cracks cause loss of material integrity by …

Towards Scaling Laws For Ddt In Obstructed Channels, Elaine S. Oran, Vadim N. Gamezo

Progress in Scale Modeling, an International Journal

In a coal mine, natural gas can leak through walls and accumulate in enclosed regions that are no longer being mined or ventilated. If there is an accidental spark in the region containing this gas, it can ignite a flame that may transition to detonation (DDT). An important problem is to assess if, when, and where DDT can occur, and thus provide information needed to design strong enough barriers to protect active mining areas. We describe results of numerical simulations of flame acceleration and DDT in obstacle-laden channels to find a scaling law for 𝐿_DDT, the distance the …

Similitude Theory Applied To Plates In Vibroacoustic Field: A Review Up To 2020, Alessandro Casaburo, Giuseppe Petrone, Francesco Franco, Sergio De Rosa

Progress in Scale Modeling, an International Journal

Similitude methods are a set of tools which allow the design of scaled-up or scaled-down models of a full-scale structure called a prototype. In this way, the financial and temporal costs of experimental tests, and the problems associated with the set-up of too large (or small) test articles, may be overcome. This article provides a brief review of similitude methods applied to plates in a vibroacoustic field. Particularly, it is dedicated to a thorough analysis of similitude conditions and scaling laws for uncovering commonalities and differences, and physical interpretations, obtained from applying different scaling methods.

Scaling Considerations For Fire Whirls, Forman A. Williams

Progress in Scale Modeling, an International Journal

This brief report, based on a presentation made at the Eighth International Symposium on Scale Modeling, held in Portland, Oregon, in September of 2017, summarizes and evaluates different methods for classifying fire whirls and their scaling laws. It is indicated that a number of relevant non-dimensional parameters are known for fire whirls, and future scale-modeling experiments could provide useful additional information and insights.

Scaling Realistic Fire Scenarios, James G. Quintiere

Progress in Scale Modeling, an International Journal

A review is made of work on scale modeling in fire and presented from the experience of the author. Primarily, scale modeling in air is discussed but there is a brief discussion of a scale model with salt and fresh water for smoke movement. A complete set of dimensionless groups is presented for fire, then it is illustrated how selections were made for the partial scaling of specific fire scenarios. Studies have been motivated by basic research interests as well as for fire investigations. The dynamics of floorcovering fire spread in a corridor is studied to reveal many features of …

What You Don’T See, Brent Sturlaugson

Architecture Faculty Publications

Follow the supply chains of architecture and you’ll find not just product manufacturers but also environmental polluters and elusive networks of financial power and political influence.

Vibration Of Steel-Framed Floors Supporting Sensitive Equipment In Hospitals, Research Facilities, And Manufacturing Facilities, Di Liu

Theses and Dissertations--Civil Engineering

Floors have traditionally been designed only for strength and deflection serviceability. As technological advances have been made in medical, scientific and micro-electronics manufacturing, many types of equipment have become sensitive to vibration of the supporting floor. Thus, vibration serviceability has become a routinely evaluated limit state for floors supporting sensitive equipment. Equipment vibration tolerance limits are sometimes expressed as waveform peak acceleration, and are more often expressed as narrowband spectral acceleration, or one-third octave spectral velocity.

Current floor vibration prediction methods, such as those found in the American Institute of Steel Construction Design Guide 11, Floor Vibrations Due to Human …