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C. Gutiérrez-Montes
Área de Mecánica de Fluidos, Departamento de Ingeniería Mecánica y Minera. Universidad de Jaén. Campus de las Lagunillas, Jaén, 23071, Spain

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Journal article
Published: 22 June 2021 in International Journal of Multiphase Flow
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The turbulent breakup of bubbles is a complex phenomenon present in a large number of engineering applications and natural processes. Simplified models are essential to better understand the interaction between turbulent eddies and bubbles. Probably the simplest one is that given by a vortex ring colliding with a single bubble. With this motivation, in the present work we perform three-dimensional numerical simulations of a single vortex ring of initial circulation Γ0, radius R0 and Reynolds number Re=Γ0/νl=15,000, interacting with a bubble of radius Rb immersed in a liquid of kinematic viscosity νl. The temporal evolution of the vortex ring is compared with analytical models for the size of the vortex core, a(t), the kinetic energy, Ek(t), and the enstrophy Ω(t), looking for a concurrence of this magnitude with the rate of dissipation of Ek. The dynamics of the bubble-vortex interaction process is described varying the vortex-to-bubble size ratio, R0/Rb, and the Weber number, We=ρl(Γ0/2πR0)2/(σ/Rb). With respect to the bubble, the simulations show that vortices smaller or of the same size as the bubble are not able to break it up. However, vortices slightly larger, although of comparable sizes, can efficiently break the bubble after trapping it inside the vortex core. In these cases, if the Weber number is sufficiently large, the bubble migrates to the vortex core, where the strain is maximum, and elongates along the azimuthal direction to eventually break by a Rayleigh-Plateau mechanism. In fact, we observe that the bubbles always break if We⪆1 when R0/Rb>1. The numerical results are corroborated experimentally for vortex-to-bubble diameter ratios in the range 2.28≤R0/Rb≤7.5. Regarding the vortex ring, it is observed that when the vortex decelerates the bubble while they interact, the vorticity contained in the bubble boundary layer is engulfed by the vortex core, destabilizing the vortex ring. This makes the total enstrophy to suddenly increase due to the vorticity generation by the vortex stretching mechanism that follows the lost of axial symmetry. This increase in enstrophy is associated to a rapid decrease of kinetic energy, especially at low Weber numbers.

ACS Style

F.J. Foronda-Trillo; J. Rodríguez-Rodríguez; C. Gutiérrez-Montes; C. Martínez-Bazán. Deformation and breakup of bubbles interacting with single vortex rings. International Journal of Multiphase Flow 2021, 142, 103734 .

AMA Style

F.J. Foronda-Trillo, J. Rodríguez-Rodríguez, C. Gutiérrez-Montes, C. Martínez-Bazán. Deformation and breakup of bubbles interacting with single vortex rings. International Journal of Multiphase Flow. 2021; 142 ():103734.

Chicago/Turabian Style

F.J. Foronda-Trillo; J. Rodríguez-Rodríguez; C. Gutiérrez-Montes; C. Martínez-Bazán. 2021. "Deformation and breakup of bubbles interacting with single vortex rings." International Journal of Multiphase Flow 142, no. : 103734.

Journal article
Published: 30 January 2021 in Applied Mathematical Modelling
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The motion of the cerebrospinal fluid in the spinal subarachnoid space, a slender annular canal surrounding the spinal cord, exhibits an oscillatory velocity component driven by the pressure oscillations induced by the cardiac and respiratory cycles. A time-averaged transport equation has been recently proposed for describing solute transport along the canal, circumventing the need to compute the concentration fluctuations resulting from this fast oscillatory motion. The accuracy and limitations of this time-averaged description are tested here by means of comparisons with results of direct numerical simulations spanning hundreds of oscillation cycles, as needed to generate significant dispersion of the solute. The comparisons between the numerical results and the predictions of the analytical model include velocity fields and quantifications of transient solute-dispersion events for selected values of the flow parameters and two different idealized, canonical geometries of the spinal canal. The comparisons clearly demonstrate the accuracy of the time-averaged description of the analytical model, which is seen to provide a good fidelity at a fraction of the computational cost involved in the direct numerical simulations. The variations of canal eccentricity along the spinal canal are found to play an important role in the dynamics of the solute transport, leading to the emergence of closed recirculating Lagrangian vortices that may hinder solute dispersion along the canal, as revealed by both direct numerical simulations and time-averaged results.

ACS Style

C. Gutiérrez-Montes; W. Coenen; J.J. Lawrence; C. Martínez-Bazán; A.L. Sánchez; J.C. Lasheras. Modelling and direct numerical simulation of flow and solute dispersion in the spinal subarachnoid space. Applied Mathematical Modelling 2021, 94, 516 -533.

AMA Style

C. Gutiérrez-Montes, W. Coenen, J.J. Lawrence, C. Martínez-Bazán, A.L. Sánchez, J.C. Lasheras. Modelling and direct numerical simulation of flow and solute dispersion in the spinal subarachnoid space. Applied Mathematical Modelling. 2021; 94 ():516-533.

Chicago/Turabian Style

C. Gutiérrez-Montes; W. Coenen; J.J. Lawrence; C. Martínez-Bazán; A.L. Sánchez; J.C. Lasheras. 2021. "Modelling and direct numerical simulation of flow and solute dispersion in the spinal subarachnoid space." Applied Mathematical Modelling 94, no. : 516-533.

Journal article
Published: 22 September 2020 in Sustainability
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This paper presents a numerical and experimental analysis of the patent of a device to be used in vertical-axis wind turbines (VAWTs) under extreme wind conditions. The device consists of two hemispheres interconnected by a set of conveniently implemented variable section ducts through which the wind circulates to the blades. Furthermore, the design of the cross-section of the ducts allows the control of the wind speed inside the device. These ducts are intended to work as diffusers or nozzles, depending on the needs of the installation site. Simulations were performed for the case of high-speed external wind, for which the ducts act as diffusers to reduce wind speed and maintain a well-functioning internal turbine. Four different patent designs were analyzed, focusing on turbine performance and generated power. The results indicate that the patent allows the generation of electric power for a greater range of wind speeds than with a normal wind turbine. The results support that this patent may be a good alternative for wind power generation in geographic areas with extreme weather conditions or with maintained or strong gusty wind. Experimental tests were carried out on the movement of the blades using the available model. Finally, the power curve of the model of this wind turbine was obtained.

ACS Style

Jose Moleón Baca; Antonio Expósito González; Candido Gutiérrez Montes. Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow. Sustainability 2020, 12, 7818 .

AMA Style

Jose Moleón Baca, Antonio Expósito González, Candido Gutiérrez Montes. Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow. Sustainability. 2020; 12 (18):7818.

Chicago/Turabian Style

Jose Moleón Baca; Antonio Expósito González; Candido Gutiérrez Montes. 2020. "Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow." Sustainability 12, no. 18: 7818.

Journal article
Published: 13 June 2019 in American Journal of Neuroradiology
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BACKGROUND AND PURPOSE: Recent flow dynamics studies have shown that the eccentricity of the spinal cord affects the magnitude and characteristics of the slow bulk motion of CSF in the spinal subarachnoid space, which is an important variable in solute transport along the spinal canal. The goal of this study was to investigate how anatomic differences among subjects affect this bulk flow. MATERIALS AND METHODS: T2-weighted spinal images were obtained in 4 subjects and repeated in 1 subject after repositioning. CSF velocity was calculated from phase-contrast MR images for 7 equally spaced levels along the length of the spine. This information was input into a 2-time-scale asymptotic analysis of the Navier-Stokes and concentration equations to calculate the short- and long-term CSF flow in the spinal subarachnoid space. Bulk flow streamlines were shown for each subject and position and inspected for differences in patterns. RESULTS: The 4 subjects had variable degrees of lordosis and kyphosis. Repositioning in 1 subject changed the degree of cervical lordosis and thoracic kyphosis. The streamlines of bulk flow show the existence of distinct regions where the fluid particles flow in circular patterns. The location and interconnectivity of these recirculating regions varied among individuals and different positions. CONCLUSIONS: Lordosis, kyphosis, and spinal cord eccentricity in the healthy human spine result in subject-specific patterns of bulk flow recirculating regions. The extent of the interconnectivity of the streamlines among these recirculating regions is fundamental in determining the long-term transport of solute particles along the spinal canal.

ACS Style

W. Coenen; C. Gutiérrez-Montes; S. Sincomb; E. Criado-Hidalgo; K. Wei; K. King; V. Haughton; C. Martínez-Bazán; A.L. Sánchez; J. C. Lasheras. Subject-Specific Studies of CSF Bulk Flow Patterns in the Spinal Canal: Implications for the Dispersion of Solute Particles in Intrathecal Drug Delivery. American Journal of Neuroradiology 2019, 40, 1242 -1249.

AMA Style

W. Coenen, C. Gutiérrez-Montes, S. Sincomb, E. Criado-Hidalgo, K. Wei, K. King, V. Haughton, C. Martínez-Bazán, A.L. Sánchez, J. C. Lasheras. Subject-Specific Studies of CSF Bulk Flow Patterns in the Spinal Canal: Implications for the Dispersion of Solute Particles in Intrathecal Drug Delivery. American Journal of Neuroradiology. 2019; 40 (7):1242-1249.

Chicago/Turabian Style

W. Coenen; C. Gutiérrez-Montes; S. Sincomb; E. Criado-Hidalgo; K. Wei; K. King; V. Haughton; C. Martínez-Bazán; A.L. Sánchez; J. C. Lasheras. 2019. "Subject-Specific Studies of CSF Bulk Flow Patterns in the Spinal Canal: Implications for the Dispersion of Solute Particles in Intrathecal Drug Delivery." American Journal of Neuroradiology 40, no. 7: 1242-1249.

Article
Published: 14 December 2018 in Fire Technology
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The design of smoke management systems in large-volume enclosures is of utter importance for life safety, property protection, and business continuity in case of fire. Despite the recent international trend in smoke control design towards the use of advanced fire models, simple plume entrainment correlations are the basis of the discipline and are still a common practice since they are often incorporated in technical documents for the design of smoke control systems. Different plume entrainment correlations have been developed over the years and are cited in different national codes and design guides. These correlations have been widely investigated for fires in small enclosures, but their applicability and accuracy in large enclosures is not clear. The present work studies the suitability and applicability of these approaches to properly predict the fire induced conditions within large volumes. The results obtained from the plume entrainment correlations have been compared with full scale experimental data in an 8.000 m3 enclosure. Based on the results obtained by this analysis performed in a large-volume enclosure, the current methods available of modelling fire and determining the smoke produced by the fire might not be suitable. It was observed that for the steady state, the McCaffrey correlation gave results closest to the experiments, and for the transient evolution of the smoke layer, the Zukoski correlation. On the contrary, the popular Thomas method underpredicted smoke production and entrainment, giving the highest smoke layer interface heights and leading to estimations that are not conservative (with errors between 36.5% and 101%). The authors analyze the reasons for the discrepancies and give some practical recommendations for the design of smoke control in large volume buildings, such as that the use of such models to predict the smoke production of a given fire shall be only a first approximation and not a design tool, especially when using those models that have not shown a good match to the experimental data.

ACS Style

Gabriele Vigne; Cándido Gutierrez-Montes; Alexis Cantizano; Wojciech Węgrzyński; Guillermo Rein. Review and Validation of the Current Smoke Plume Entrainment Models for Large-Volume Buildings. Fire Technology 2018, 55, 789 -816.

AMA Style

Gabriele Vigne, Cándido Gutierrez-Montes, Alexis Cantizano, Wojciech Węgrzyński, Guillermo Rein. Review and Validation of the Current Smoke Plume Entrainment Models for Large-Volume Buildings. Fire Technology. 2018; 55 (3):789-816.

Chicago/Turabian Style

Gabriele Vigne; Cándido Gutierrez-Montes; Alexis Cantizano; Wojciech Węgrzyński; Guillermo Rein. 2018. "Review and Validation of the Current Smoke Plume Entrainment Models for Large-Volume Buildings." Fire Technology 55, no. 3: 789-816.

Article
Published: 30 April 2018 in Fire Technology
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In case of fire, constructive features of typical atria could favor the spread of smoke. This makes the design of their smoke control and management systems a challenging task. Five full-scale fire experiments in the literature have been analyzed and numerically compared in FDS v6 to explore the influence of the make-up air. However, these fire experiments cover only a limited number of set-ups and conditions, and require further numerical modeling to obtain a deeper understanding of the makeup air influence. Subsequently, 84 simulations with FDS v6 have been carried out, considering different vent areas (air velocity from 0.4 to 5.3 m/s) and configurations, two heat release rates (2.5 and 5 MW), and two pan locations. It is demonstrated that make-up air velocities lower than the prescribed limit of 1 m/s, by the international codes, may induce adverse conditions. Based on our results, we recommended fire engineers to numerically assess the fire scenario with even lower velocity values. The results also show that asymmetric configurations are prone to induce circulation around the flame which can contribute to the formation of longer flames and fire whirls. Thus, this numerical study links two fire types allowing the connection of pool fires to fire whirls, which completely differ in behaviour and smoke filling, for the sake of design of fire safety.

ACS Style

Pablo Ayala; Alexis Cantizano; Guillermo Rein; Cándido Gutiérrez-Montes. Factors Affecting the Make-Up Air and Their Influence on the Dynamics of Atrium Fires. Fire Technology 2018, 54, 1067 -1091.

AMA Style

Pablo Ayala, Alexis Cantizano, Guillermo Rein, Cándido Gutiérrez-Montes. Factors Affecting the Make-Up Air and Their Influence on the Dynamics of Atrium Fires. Fire Technology. 2018; 54 (4):1067-1091.

Chicago/Turabian Style

Pablo Ayala; Alexis Cantizano; Guillermo Rein; Cándido Gutiérrez-Montes. 2018. "Factors Affecting the Make-Up Air and Their Influence on the Dynamics of Atrium Fires." Fire Technology 54, no. 4: 1067-1091.

Conference paper
Published: 01 April 2018 in Proceedings of the 3rd World Congress on Momentum, Heat and Mass Transfer
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ACS Style

Javier Ruiz-Rus; Rocío Bolanos-Jimenez; Cándido Gutierrez-Montes; Alejandro Sevilla; Carlos Martínez-Bazan. Enhanced Bubble Generation by an Air-Stimulated Co-Flow System. Proceedings of the 3rd World Congress on Momentum, Heat and Mass Transfer 2018, 1 .

AMA Style

Javier Ruiz-Rus, Rocío Bolanos-Jimenez, Cándido Gutierrez-Montes, Alejandro Sevilla, Carlos Martínez-Bazan. Enhanced Bubble Generation by an Air-Stimulated Co-Flow System. Proceedings of the 3rd World Congress on Momentum, Heat and Mass Transfer. 2018; ():1.

Chicago/Turabian Style

Javier Ruiz-Rus; Rocío Bolanos-Jimenez; Cándido Gutierrez-Montes; Alejandro Sevilla; Carlos Martínez-Bazan. 2018. "Enhanced Bubble Generation by an Air-Stimulated Co-Flow System." Proceedings of the 3rd World Congress on Momentum, Heat and Mass Transfer , no. : 1.

Journal article
Published: 01 April 2018 in Physics of Fluids
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We investigate experimentally and numerically the transient development of the wake induced by a constant acceleration of a D-shaped bluff body, starting from rest and reaching a permanent regime of Reynolds number Re = 2000, under different values of acceleration and implementing three distinct rear geometrical configurations. Thus, alongside the classical blunt base, two control passive devices, namely, a straight cavity and an optimized, curved cavity, recently designed using adjoint optimization techniques, have also been used to assess their performance in transient flow conditions. Particle image velocimetry measurements were performed in a towing tank to characterize the near wake development in the early transient stages. It has been observed that the flow first develops symmetric shear layers with primary eddies attracted toward the base of the body due to the flow suction generated by the accelerated motion. Eventually, the interaction between the upper and lower shear layers provokes the destabilization of the flow and the symmetry breaking of the wake, finally giving rise to an alternate transitional vortex shedding regime. The transition between these phases is sped-up when the optimized cavity is used, reaching earlier the permanent flow conditions. In particular, the use of the optimized geometry has been shown to limit the growth of the primary eddies, decreasing both the recirculation and vortex formation length and providing with a more regularized, more organized vortex shedding. In addition, numerical simulations have been performed to evaluate the distribution of forces induced by the addition of rear cavities. In general, the aforementioned smoother and faster transition related to the use of optimized cavity translates into a lower averaged value of the drag coefficient, together with less energetic force fluctuations, regardless of the acceleration value.

ACS Style

M. Lorite-Díez; J. I. Jiménez-González; C. Gutiérrez-Montes; C. Martínez-Bazán. Effects of rear cavities on the wake behind an accelerating D-shaped bluff body. Physics of Fluids 2018, 30, 044103 .

AMA Style

M. Lorite-Díez, J. I. Jiménez-González, C. Gutiérrez-Montes, C. Martínez-Bazán. Effects of rear cavities on the wake behind an accelerating D-shaped bluff body. Physics of Fluids. 2018; 30 (4):044103.

Chicago/Turabian Style

M. Lorite-Díez; J. I. Jiménez-González; C. Gutiérrez-Montes; C. Martínez-Bazán. 2018. "Effects of rear cavities on the wake behind an accelerating D-shaped bluff body." Physics of Fluids 30, no. 4: 044103.

Journal article
Published: 20 February 2018 in Journal of Fluid Mechanics
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Radionuclide scanning images published inNatureby Di Chiro in 1964 showed a downward migration along the spinal canal of particle tracers injected in the brain ventricles while also showing an upward flow of tracers injected in the lumbar region of the canal. These observations, since then corroborated by many radiological measurements, have been the basis for the hypothesis that there must be an active circulation mechanism associated with the transport of cerebrospinal fluid (CSF) deep down into the spinal canal and subsequently returning a portion back to the cranial vault. However, to date, there has been no physical explanation for the mechanism responsible for the establishment of such a bulk recirculating motion. To investigate the origin and characteristics of this recirculating flow, we have analyzed the motion of the CSF in the subarachnoid space of the spinal canal. Our analysis accounts for the slender geometry of the spinal canal, the small compliance of the dura membrane enclosing the CSF in the canal, and the fact that the CSF is confined to a thin annular subarachnoid space surrounding the spinal cord. We apply this general formulation to study the characteristics of the flow generated in a simplified model of the spinal canal consisting of a slender compliant cylindrical pipe with a coaxial cylindrical inclusion, closed at its distal end, and subjected to small periodic pressure pulsations at its open entrance. We show that the balance between the local acceleration and viscous forces produces a leading-order flow consisting of pure oscillatory motion with axial velocities on the order of a few centimetres per second and amplitudes monotonically decreasing along the length of the canal. We then demonstrate that the nonlinear term associated with the convective acceleration contributes to a second-order correction consisting of a steady streaming that generates a bulk recirculating motion of the CSF along the length of the canal with characteristic velocities two orders of magnitude smaller than the leading-order oscillatory flow. The results of the analysis of this idealized geometry of the spinal canal are shown to be in good agreement not only with experimental measurements in anin-vitromodel but also with radiological measurements conducted in human adults.

ACS Style

A. L. Sánchez; C. Martínez-Bazán; C. Gutiérrez-Montes; Ernesto Criado-Hidalgo; G. Pawlak; W. Bradley; V. Haughton; J. C. Lasheras. On the bulk motion of the cerebrospinal fluid in the spinal canal. Journal of Fluid Mechanics 2018, 841, 203 -227.

AMA Style

A. L. Sánchez, C. Martínez-Bazán, C. Gutiérrez-Montes, Ernesto Criado-Hidalgo, G. Pawlak, W. Bradley, V. Haughton, J. C. Lasheras. On the bulk motion of the cerebrospinal fluid in the spinal canal. Journal of Fluid Mechanics. 2018; 841 ():203-227.

Chicago/Turabian Style

A. L. Sánchez; C. Martínez-Bazán; C. Gutiérrez-Montes; Ernesto Criado-Hidalgo; G. Pawlak; W. Bradley; V. Haughton; J. C. Lasheras. 2018. "On the bulk motion of the cerebrospinal fluid in the spinal canal." Journal of Fluid Mechanics 841, no. : 203-227.

Journal article
Published: 01 December 2017 in International Journal of Multiphase Flow
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ACS Style

J.C. Cano-Lozano; Rocio Bolaños-Jiménez; C. Gutiérrez-Montes; Carlos Martinez-Bazan. On the bubble formation under mixed injection conditions from a vertical needle. International Journal of Multiphase Flow 2017, 97, 23 -32.

AMA Style

J.C. Cano-Lozano, Rocio Bolaños-Jiménez, C. Gutiérrez-Montes, Carlos Martinez-Bazan. On the bubble formation under mixed injection conditions from a vertical needle. International Journal of Multiphase Flow. 2017; 97 ():23-32.

Chicago/Turabian Style

J.C. Cano-Lozano; Rocio Bolaños-Jiménez; C. Gutiérrez-Montes; Carlos Martinez-Bazan. 2017. "On the bubble formation under mixed injection conditions from a vertical needle." International Journal of Multiphase Flow 97, no. : 23-32.

Journal article
Published: 01 October 2017 in Journal of Fluids and Structures
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ACS Style

M. Lorite-Díez; J.I. Jiménez-González; C. Gutiérrez-Montes; Carlos Martinez-Bazan. Drag reduction of slender blunt-based bodies using optimized rear cavities. Journal of Fluids and Structures 2017, 74, 158 -177.

AMA Style

M. Lorite-Díez, J.I. Jiménez-González, C. Gutiérrez-Montes, Carlos Martinez-Bazan. Drag reduction of slender blunt-based bodies using optimized rear cavities. Journal of Fluids and Structures. 2017; 74 ():158-177.

Chicago/Turabian Style

M. Lorite-Díez; J.I. Jiménez-González; C. Gutiérrez-Montes; Carlos Martinez-Bazan. 2017. "Drag reduction of slender blunt-based bodies using optimized rear cavities." Journal of Fluids and Structures 74, no. : 158-177.

Journal article
Published: 25 April 2017 in Atmospheric Chemistry and Physics
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Ambient pine forest air was oxidized by OH, O3, or NO3 radicals using an oxidation flow reactor (OFR) during the BEACHON-RoMBAS (Bio–hydro–atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen – Rocky Mountain Biogenic Aerosol Study) campaign to study biogenic secondary organic aerosol (SOA) formation and organic aerosol (OA) aging. A wide range of equivalent atmospheric photochemical ages was sampled, from hours up to days (for O3 and NO3) or weeks (for OH). Ambient air processed by the OFR was typically sampled every 20–30 min, in order to determine how the availability of SOA precursor gases in ambient air changed with diurnal and synoptic conditions, for each of the three oxidants. More SOA was formed during nighttime than daytime for all three oxidants, indicating that SOA precursor concentrations were higher at night. At all times of day, OH oxidation led to approximately 4 times more SOA formation than either O3 or NO3 oxidation. This is likely because O3 and NO3 will only react with gases containing C = C bonds (e.g., terpenes) to form SOA but will not react appreciably with many of their oxidation products or any species in the gas phase that lacks a C = C bond (e.g., pinonic acid, alkanes). In contrast, OH can continue to react with compounds that lack C = C bonds to produce SOA. Closure was achieved between the amount of SOA formed from O3 and NO3 oxidation in the OFR and the SOA predicted to form from measured concentrations of ambient monoterpenes and sesquiterpenes using published chamber yields. This is in contrast to previous work at this site (Palm et al., 2016), which has shown that a source of SOA from semi- and intermediate-volatility organic compounds (S/IVOCs) 3.4 times larger than the source from measured VOCs is needed to explain the measured SOA formation from OH oxidation. This work suggests that those S/IVOCs typically do not contain C = C bonds. O3 and NO3 oxidation produced SOA with elemental O : C and H : C similar to the least-oxidized OA observed in local ambient air, and neither oxidant led to net mass loss at the highest exposures, in contrast to OH oxidation. An OH exposure in the OFR equivalent to several hours of atmospheric aging also produced SOA with O : C and H : C values similar to ambient OA, while higher aging (days–weeks) led to formation of SOA with progressively higher O : C and lower H : C (and net mass loss at the highest exposures). NO3 oxidation led to the production of particulate organic nitrates (pRONO2), while OH and O3 oxidation (under low NO) did not, as expected. These measurements of SOA formation provide the first direct comparison of SOA formation potential and chemical evolution from OH, O3, and NO3 oxidation in the real atmosphere and help to clarify the oxidation processes that lead to SOA formation from biogenic hydrocarbons.

ACS Style

Brett B. Palm; Pedro Campuzano-Jost; Douglas A. Day; Amber M. Ortega; Juliane L. Fry; Steven S. Brown; Kyle J. Zarzana; William Dube; Nicholas L. Wagner; Danielle C. Draper; Lisa Kaser; Werner Jud; Thomas Karl; Armin Hansel; Cándido Gutiérrez-Montes; Jose L. Jimenez. Secondary organic aerosol formation from in situ OH, O3, and NO3 oxidation of ambient forest air in an oxidation flow reactor. Atmospheric Chemistry and Physics 2017, 17, 5331 -5354.

AMA Style

Brett B. Palm, Pedro Campuzano-Jost, Douglas A. Day, Amber M. Ortega, Juliane L. Fry, Steven S. Brown, Kyle J. Zarzana, William Dube, Nicholas L. Wagner, Danielle C. Draper, Lisa Kaser, Werner Jud, Thomas Karl, Armin Hansel, Cándido Gutiérrez-Montes, Jose L. Jimenez. Secondary organic aerosol formation from in situ OH, O3, and NO3 oxidation of ambient forest air in an oxidation flow reactor. Atmospheric Chemistry and Physics. 2017; 17 (8):5331-5354.

Chicago/Turabian Style

Brett B. Palm; Pedro Campuzano-Jost; Douglas A. Day; Amber M. Ortega; Juliane L. Fry; Steven S. Brown; Kyle J. Zarzana; William Dube; Nicholas L. Wagner; Danielle C. Draper; Lisa Kaser; Werner Jud; Thomas Karl; Armin Hansel; Cándido Gutiérrez-Montes; Jose L. Jimenez. 2017. "Secondary organic aerosol formation from in situ OH, O3, and NO3 oxidation of ambient forest air in an oxidation flow reactor." Atmospheric Chemistry and Physics 17, no. 8: 5331-5354.

Journal article
Published: 01 March 2017 in International Journal of Multiphase Flow
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ACS Style

J. Ruiz-Rus; R. Bolaños-Jiménez; C. Gutiérrez-Montes; Alejandro Sevilla; Carlos Martinez-Bazan. Controlled formation of bubbles in a planar co-flow configuration. International Journal of Multiphase Flow 2017, 89, 69 -80.

AMA Style

J. Ruiz-Rus, R. Bolaños-Jiménez, C. Gutiérrez-Montes, Alejandro Sevilla, Carlos Martinez-Bazan. Controlled formation of bubbles in a planar co-flow configuration. International Journal of Multiphase Flow. 2017; 89 ():69-80.

Chicago/Turabian Style

J. Ruiz-Rus; R. Bolaños-Jiménez; C. Gutiérrez-Montes; Alejandro Sevilla; Carlos Martinez-Bazan. 2017. "Controlled formation of bubbles in a planar co-flow configuration." International Journal of Multiphase Flow 89, no. : 69-80.

Journal article
Published: 16 July 2016 in Fire Technology
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In order to mitigate the excessive computational cost of atrium fire simulations, a novel methodology based on the use of the Fractional Factorial Design technique to obtain an experimental validated tool, in the form of a surface response model, capable to predict fire induced conditions is proposed. This methodology is supported by results from a Design of Experiments benchmark, which consists of a set of FDS simulations in the present work. Specifically, a \(2^{6-2}_{IV}\) approach has been considered and applied to a 20 m cubic atrium. Thus, six factors have been considered, namely the fire Heat Release Rate (HRR) and location, the exhaust flow rate, the exhaust location and activation time, and the inlet vents area. Furthermore, the smoke temperature at the roof and 15 m high and the smoke layer height have been considered the variables of interest. Subsequently, a multiple linear regression analysis has been performed to predict and compare the steady and non-steady temperature profiles and the smoke layer drop with six novel full-scale atrium fire tests, and also with specific adjusted FDS models. In addition, this methodology has been extended successfully to predict the non-steady behaviour of the fire tests. At the steady state, the HRR and the exhaust flow rate have been found to be the most relevant factors. The results obtained with the proposed methodology show a good fit both with the fire tests and with the adjusted FDS models, with discrepancies mostly below 14%. For non-steady conditions, a time analysis of the influence of the six factors has been carried out. Again, remarkable good agreement with the time-dependent experimental results is achieved, with average discrepancies below 12%, being the larger differences found in the prediction of local effects, such as the smoke ceiling jet, for high HRR or when the make-up air influence is significant. The results turn this methodology into a powerful and useful tool for fire safety designs.

ACS Style

Pablo Ayala; A. Cantizano; Eugenio Sánchez-Úbeda; C. Gutiérrez-Montes. The Use of Fractional Factorial Design for Atrium Fires Prediction. Fire Technology 2016, 53, 893 -916.

AMA Style

Pablo Ayala, A. Cantizano, Eugenio Sánchez-Úbeda, C. Gutiérrez-Montes. The Use of Fractional Factorial Design for Atrium Fires Prediction. Fire Technology. 2016; 53 (2):893-916.

Chicago/Turabian Style

Pablo Ayala; A. Cantizano; Eugenio Sánchez-Úbeda; C. Gutiérrez-Montes. 2016. "The Use of Fractional Factorial Design for Atrium Fires Prediction." Fire Technology 53, no. 2: 893-916.

Journal article
Published: 15 June 2016 in Atmospheric Chemistry and Physics
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Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient and reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days–6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8–6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ∼ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ∼ −0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ∼ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and also extends to higher ages where OA loss dominates. The mass added at low-to-intermediate ages is due primarily to condensation of oxidized species, not heterogeneous oxidation. The OA decrease at high photochemical ages is dominated by heterogeneous oxidation followed by fragmentation/evaporation. A comparison of urban SOA formation in this study with a similar study of vehicle SOA in a tunnel suggests the importance of vehicle emissions for urban SOA. Pre-2007 SOA models underpredict SOA formation by an order of magnitude, while a more recent model performs better but overpredicts at higher ages. These results demonstrate the value of the reactor as a tool for in situ evaluation of the SOA formation potential and OA evolution from ambient air.

ACS Style

Amber M. Ortega; Patrick L. Hayes; Zhe Peng; Brett B. Palm; Weiwei Hu; Douglas A. Day; Rui Li; Michael J. Cubison; William H. Brune; Martin Graus; Carsten Warneke; Jessica B. Gilman; William C. Kuster; Joost de Gouw; Cándido Gutiérrez-Montes; Jose L. Jimenez. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area. Atmospheric Chemistry and Physics 2016, 16, 7411 -7433.

AMA Style

Amber M. Ortega, Patrick L. Hayes, Zhe Peng, Brett B. Palm, Weiwei Hu, Douglas A. Day, Rui Li, Michael J. Cubison, William H. Brune, Martin Graus, Carsten Warneke, Jessica B. Gilman, William C. Kuster, Joost de Gouw, Cándido Gutiérrez-Montes, Jose L. Jimenez. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area. Atmospheric Chemistry and Physics. 2016; 16 (11):7411-7433.

Chicago/Turabian Style

Amber M. Ortega; Patrick L. Hayes; Zhe Peng; Brett B. Palm; Weiwei Hu; Douglas A. Day; Rui Li; Michael J. Cubison; William H. Brune; Martin Graus; Carsten Warneke; Jessica B. Gilman; William C. Kuster; Joost de Gouw; Cándido Gutiérrez-Montes; Jose L. Jimenez. 2016. "Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area." Atmospheric Chemistry and Physics 16, no. 11: 7411-7433.

Journal article
Published: 11 June 2015 in Fire Technology
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An experimental and numerical comparison of new full-scale atrium fire tests in the 20 m cubic atrium with four different heat release rates (1.7 MW, 2.3 MW, 3.9 MW and 5.3 MW) is presented. Different exhaust conditions (steady and transient extraction rates) and different make-up air configurations (symmetric and asymmetric) are assessed. Temperature measurements in the near (fire plume) and far field (close to the walls) have been recorded by means of 59 thermocouples. The smoke layer interface is also estimated by means of a thermocouple tree with 28 measurements using the least-square and the n-percent methods. The simulations have been conducted using FDS (version 6, Release Candidate 3). The comparison with the simulations shows average discrepancies lower than 32% and 11%, for the near and far field temperatures, respectively. A discrepancy lower than 5% (1 m) is obtained by both methods for the smoke layer height when the steady state is reached. Finally, a slower response to an increment on the exhaust rate is predicted on the smoke layer, being more perceptible for high heat release rates.

ACS Style

P. Ayala; Alexis Cantizano; Guillermo Rein; Gabriele Vigne; C. Gutiérrez-Montes. Fire Experiments and Simulations in a Full-scale Atrium Under Transient and Asymmetric Venting Conditions. Fire Technology 2015, 52, 51 -78.

AMA Style

P. Ayala, Alexis Cantizano, Guillermo Rein, Gabriele Vigne, C. Gutiérrez-Montes. Fire Experiments and Simulations in a Full-scale Atrium Under Transient and Asymmetric Venting Conditions. Fire Technology. 2015; 52 (1):51-78.

Chicago/Turabian Style

P. Ayala; Alexis Cantizano; Guillermo Rein; Gabriele Vigne; C. Gutiérrez-Montes. 2015. "Fire Experiments and Simulations in a Full-scale Atrium Under Transient and Asymmetric Venting Conditions." Fire Technology 52, no. 1: 51-78.

Journal article
Published: 01 June 2015 in Applied Mathematical Modelling
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José Carlos Cano-Lozano; Rocio Bolaños-Jiménez; C. Gutiérrez-Montes; Carlos Martinez-Bazan. The use of Volume of Fluid technique to analyze multiphase flows: Specific case of bubble rising in still liquids. Applied Mathematical Modelling 2015, 39, 3290 -3305.

AMA Style

José Carlos Cano-Lozano, Rocio Bolaños-Jiménez, C. Gutiérrez-Montes, Carlos Martinez-Bazan. The use of Volume of Fluid technique to analyze multiphase flows: Specific case of bubble rising in still liquids. Applied Mathematical Modelling. 2015; 39 (12):3290-3305.

Chicago/Turabian Style

José Carlos Cano-Lozano; Rocio Bolaños-Jiménez; C. Gutiérrez-Montes; Carlos Martinez-Bazan. 2015. "The use of Volume of Fluid technique to analyze multiphase flows: Specific case of bubble rising in still liquids." Applied Mathematical Modelling 39, no. 12: 3290-3305.

Journal article
Published: 01 October 2014 in International Journal of Multiphase Flow
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C. Gutiérrez-Montes; Rocio Bolaños-Jiménez; Alejandro Sevilla; Carlos Martinez-Bazan. Bubble formation in a planar water–air–water jet: Effects of the nozzle geometry and the injection conditions. International Journal of Multiphase Flow 2014, 65, 38 -50.

AMA Style

C. Gutiérrez-Montes, Rocio Bolaños-Jiménez, Alejandro Sevilla, Carlos Martinez-Bazan. Bubble formation in a planar water–air–water jet: Effects of the nozzle geometry and the injection conditions. International Journal of Multiphase Flow. 2014; 65 ():38-50.

Chicago/Turabian Style

C. Gutiérrez-Montes; Rocio Bolaños-Jiménez; Alejandro Sevilla; Carlos Martinez-Bazan. 2014. "Bubble formation in a planar water–air–water jet: Effects of the nozzle geometry and the injection conditions." International Journal of Multiphase Flow 65, no. : 38-50.

Journal article
Published: 01 July 2014 in Journal of Fluids and Structures
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A. Martín-Alcántara; E. Sanmiguel-Rojas; C. Gutiérrez-Montes; C. Martínez-Bazán. Drag reduction induced by the addition of a multi-cavity at the base of a bluff body. Journal of Fluids and Structures 2014, 48, 347 -361.

AMA Style

A. Martín-Alcántara, E. Sanmiguel-Rojas, C. Gutiérrez-Montes, C. Martínez-Bazán. Drag reduction induced by the addition of a multi-cavity at the base of a bluff body. Journal of Fluids and Structures. 2014; 48 ():347-361.

Chicago/Turabian Style

A. Martín-Alcántara; E. Sanmiguel-Rojas; C. Gutiérrez-Montes; C. Martínez-Bazán. 2014. "Drag reduction induced by the addition of a multi-cavity at the base of a bluff body." Journal of Fluids and Structures 48, no. : 347-361.

Journal article
Published: 01 October 2013 in Energy and Buildings
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Pablo Ayala; Alexis Cantizano; Cándido Gutiérrez-Montes; Guillermo Rein. Influence of atrium roof geometries on the numerical predictions of fire tests under natural ventilation conditions. Energy and Buildings 2013, 65, 382 -390.

AMA Style

Pablo Ayala, Alexis Cantizano, Cándido Gutiérrez-Montes, Guillermo Rein. Influence of atrium roof geometries on the numerical predictions of fire tests under natural ventilation conditions. Energy and Buildings. 2013; 65 ():382-390.

Chicago/Turabian Style

Pablo Ayala; Alexis Cantizano; Cándido Gutiérrez-Montes; Guillermo Rein. 2013. "Influence of atrium roof geometries on the numerical predictions of fire tests under natural ventilation conditions." Energy and Buildings 65, no. : 382-390.