Physical Sciences and Mathematics Commons^™

Western Science And Eastern Zen To Seek The Origin Of Truth: Philosophical Background Of Scale Modeling, Kozo Saito

Progress in Scale Modeling, an International Journal

This article was written to introduce philosophical background of scale modeling, where Zen philosophy was applied to overcome the limitation of logical thinking and hypotheses-driven deductive science. Three specific reasons are as follows. The first is related to the law approach in scale modeling; it uses the kufu principle, originated in Zen Buddhism, together with the other three scientific methods: experimental, theoretical, and computational. The second reason is because scale modeling seeks relativistic understanding by attempting to realize similarity; the concept is closer to Eastern philosophy rather than absolute understanding cultivated by deductive science. The third is in the educational …

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 …

Scale Modeling Of An Appearance Of Downwash Pattern Of Hot Smoke Ejected From Chimney In The Turbulent Cross Flow, Xangpheuak Inthavideth, Nobumasa Sekishita, Sounthisack Phommachanh, Yuji Nakamura

Progress in Scale Modeling, an International Journal

This study aims to elucidate the scaling law to provide the critical condition on appearance of the downwash pattern of the hot smoke ejected from a chimney in a turbulent cross flow. A specially designed wind tunnel with an active turbulence generator developed by Makita was adopted to offer a quasi-isotropic turbulence field in a lab-scale test facility. A heated jet with smoke is issued into the cross flow from the vertically oriented chimney placed in the test section of the wind tunnel. In this study, the experimental parameters considered are temperature of the heated jet (smoke), jet ejected velocity, …

A Cfd-Based Scaling Analysis On Liquid And Paint Droplets Moving Through A Weak Concurrent Airflow Stream, Masoud Arabghahestani, Nelson Akafuah, Tianxiang Li, Kozo Saito

Progress in Scale Modeling, an International Journal

We conducted volume of fluids (VOF) multiphase model numerical simulations to obtain the interaction among all the major governing forces identified in our previous paper. Our numerical experiments are intended to assess the droplet generation process and the jetting behavior by providing specific input conditions, offering CFD as a tool to study scaling correlations instead of physical experiments. Water droplets that can represent waterborne paints were generated by piezo-generated sinusoidal waveforms at the inlet of the nozzle. The governing forces included the external piezo-based wave-generation force, the inertial force of droplets, the inertial force of air, the viscose force of …

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 …

Scale Model Equations And Optimization For Annular Flow Of Non-Newtonian Fluids Between Eccentric And Rotating Cylinders, Wei Zhang, Pooya Khodaparast, Amin Mehrabian Dr., Amir Shojaei

Progress in Scale Modeling, an International Journal

A broad range of engineering applications involves helical flow of non-Newtonian fluids between two eccentric cylinders. These applications often require estimation of the frictional pressure losses along the axes of the cylinders. Laboratory flow loops are commonly used to study the flow characteristics at smaller scales of investigation. This study uses the laws of similarity and dimensional analysis to obtain a set of scaling equations between the laboratory and prototype scales of the described annular flow. These equations are derived for four types of fluid rheology including Newtonian, power-law, Bingham-plastic, and yield power-law.

Results are expressed through a set of …

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 …

Scale Model Test To Estimate Thermal Damage By Fire In Aircraft Cargo, Jian Gao, Tsuneyoshi Matsuoka, Yuji Nakamura

Progress in Scale Modeling, an International Journal

The Federal Aviation Administration (FAA) requires fire detectors to alarm within one minute of the start of a fire in cargo compartments of airplanes. To determine whether such alarm timing works, investigations of the thermal damage to ceilings and other structures during the early stage of a fire were accomplished to demonstrate compliance with these FAA regulations. The objective was to test the feasibility of predicting convective heat transfer in early stage of a cargo compartment fire by conducting reduced scale (lab scale) experiments. First, the scaling laws was derived and validated. Then, full-scale and half-scale experiments were performed with …

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 …

Effects Of Dimensionless Numbers On Decomposition Of Methane Hydrate, Shoma Shimizu, Genichiro Kushida

Progress in Scale Modeling, an International Journal

It is necessary to elucidate the decomposition and combustion of methane hydrate for fire safety during transportation and storage to utilize it for commercial practice. The amount of methane evolved during the decomposition of methane hydrates is affected by the conditions such as the initial temperature, initial density and ambient temperature. In the present study, the internal temperature of methane hydrate and the amount of methane evolved during its decomposition were investigated by a dimensionless numerical analysis using a transient one-dimensional conduction model from a symmetrical methane hydrate ball heated by ambient air. The numerically calculated central temperature and the …

A Study On Fire Hazards Of Oil Tanks In Urban Areas With Scale Model Experiments, Ho Yin Ng, Yu Wan, Wan Ki Chow

Progress in Scale Modeling, an International Journal

Large fuel tanks are located in an urban area of Tsing Yi in Hong Kong, giving potentially high risks to people living nearby if a fire was to occur. Scale modeling experiments were carried out to investigate the potential of fire hazards. Propanol pool fires with five different scales of oil tanks were studied first. Appropriate tank sizes were then put in a 1/2500 architectural scale model on the Tsing Yi Island to study a fuel tank fire. Results show that the heat and smoke from a fire would affect occupants staying in areas near to the fuel tanks. Fire …

Fingering Behavior Of Flame Spread Over Solid Combustibles, Tsuneyoshi Matsuoka, Kentaro Nakashima, Takuma Kajimoto, Akihiro Yoshimasa, Yuji Nakamura

Progress in Scale Modeling, an International Journal

In this study, the fingering pattern formation and the following flamelet spreading over three different kinds of thick combustibles, i.e., Poly methacrylate (PMMA), Poly ethylene (PE) and Poly carbonate (PC) were observed and the effective Lewis number correlation was validated. Experiments were performed with a narrow channel apparatus. In addition to the kinds of solid fuel materials, the channel height and the oxidizer velocity were varied as experimental parameters. An image analysis method was developed to quantify the number, diameter and spread rate of the flamelets. Replacing the fuel thickness into the thermal thickness, the effective Lewis number which is …

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 …

A Strategy To Predict The Global Warming Gas From Stock Farming —Potential Scaling Law Of The Released Methane From Livestock—, Toshiaki Nakashima, Tsuneyoshi Matsuoka, Yuji Nakamura

Progress in Scale Modeling, an International Journal

This work examines a scaling approach to predict the amount of methane released from the daily activity of livestock on farms. The subject animals are ruminants, i.e. having rumen or a ruminant stomach, that generates methane through digestion processes via several microbial fermentation steps. The produced methane is mixed into their breathing and released into the atmosphere. Existing data on methane released from various kinds of ruminant livestock were correlated as a power function of an animal’s weight, with an exponent near 0.92. This value is larger than a value of 0.75 which was related to the general metabolism rates …

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 …

The Model Area In Successful Lean Transformation And Scale Modeling, William Cooper, M. Abbot Maginnis, David Parsley, Kozo Saito

Progress in Scale Modeling, an International Journal

The True Lean System Program at the University of Kentucky was created in 1994 to study how the development of the Toyota Production System (TPS) contributes to Toyota’s success. This increased understanding of Toyota’s experience would provide useful guidance to Western companies taking on the challenges of replicating Toyota’s success within their own organizations. The common struggle point shared by the companies who come to us is their inability to establish sustainable TPS-based Lean transformations throughout their organizations. Our work with these companies along with our study of Toyota’s own experience in bringing TPS to its own American operations has …

Scale And Numerical Modeling To Determine Operating Points Of A Non-Clogging Vortecone Filter In Mining Operation, Ashish R. Kumar, Sampurna Arya, Adam Levy, Steven Schafrik, William C. Wedding, Kozo Saito

Progress in Scale Modeling, an International Journal

Numerical and scale modeling studies of Vortecone, a pressure-driven wet-scrubber device for the efficient capture of over-sprayed paint in the automobile industry, are presented. In this manuscript, Vortecone was tested for removing dust particles from underground mining operations. The pressures required to operate Vortecone and the airflow rates through the Vortecone are the two most important factors for mine ventilation systems. This study used dry, no-particle conditions to obtain relationship between these two parameters and then designed a Vortecone filter ventilation system for mining operations. Commercial software, SC/Flow, was used to generate the CFD model with unstructured meshes and a …

Scale Modeling Of Dust Capture Through A Flooded-Bed Dust Scrubber Integrated Within A Longwall Shearer, Sampurna Arya, Ashish Kumar, Kozo Saito, Thomas Novak, Adam Levy

Progress in Scale Modeling, an International Journal

Meeting federal dust standards at a longwall mine face is among the more difficult challenges for a longwall mine operator. With recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The authors recommend the concept of controlling respirable and float dust, which is inherent in longwall mining, through the application of a flooded-bed dust scrubber to a longwall shearer. A full-scale physical model of a longwall shearer, modified with an integrated flooded-bed scrubber, was designed and fabricated at the University of Kentucky to measure the effects of a flooded-bed scrubber on dust capture …

The Behavior Of Micro Explosive Charge Underwater Explosion Near A Rigid Wall, Kazutaka Kitagawa, Atsushi Abe

Progress in Scale Modeling, an International Journal

The interactions between an underwater explosion and underwater structures is a research topic related to understanding strong impulsive forces for disaster preparation and prevention. This study is a part of series studying the behavior of underwater explosion bubbles near different boundaries and structures because understanding the boundary phases and the pulsation of bubbles could be a useful predictive tool. Micro explosive underwater explosions were conducted by detonating a very small amount of silver azide; the time evolution and attenuation of effects from the explosion were studied. Both numerical and experimental data were acquired and compared for underwater shock waves, gas …

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.