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Full-Text Articles in Physical Sciences and Mathematics

Tricritical Point As A Crossover Between Type-Is And Type-Iis Bifurcations, Prabakaran Rajamanickam, Joel Daou Oct 2023

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-Is and (stationary longwave) type-IIs 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 Aug 2023

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 …