Publications

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Journals

• Comparision of two methods for evaluating the performance of particle filtration systems in underground railway stations , V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, Indoor Environments, 12/2025 [DOI]
  • Abstract

    Filtration is one of the strategies that can be implemented to mitigate the public health challenge due to elevated concentrations of particles in underground railway stations (URS). During a particle (PM2.5 and PM10) monitoring campaign performed in a Paris URS over more than 5 years, two filtration systems were tested. One of these systems employs positive ionization (Experiment 1), the second one is based on water filtration (Experiment 2). The present study focuses on evaluating the performance of these experiments, using two distinct methods: the daily amplitude coefficient (DAC), and a generalized additive model (GAM). The DAC method requires only particulate matter measurements, while the GAM method necessitates additional measurements (indoor CO2 concentration, temperature and humidity, outdoor pollutant concentration) as it analyses the nonlinear relationships between all these factors. The results show that both filtration technologies are more effective at reducing PM2.5 concentrations than PM10, but Experiment 2 was less efficient than Experiment 1. Specifically, DAC analysis leads to a reduction of 17.8 ± 3.2% for PM10 and 25.9 ± 6.6% for PM2.5 for Experiment 1, compared to only 0.4 ± 0.1% for PM10 and 3.7 ± 1.0% for PM2.5 for Experiment 2. GAM analysis gives similar results, with a reduction of 13.1 ± 0.8% for PM10 and 26.0 ± 0.8 for PM2.5 for Experiment 1, and for Experiment 2 a reduction of 1.3 ± 2.0% for PM10 and 4.6 ± 1.3% for PM2.5. Yet, because of differences in the filtration setups, such as the position of the modules and the maximal air flow capacity, and of unspecified internal characteristics of the systems, no conclusion can be drawn as to whether one of the filtration techniques is more efficient than the other. The two analysis methodologies lead to similar results and allow to fully and rigorously exploit long time series. The DAC method can be applied using only PM measurements, while the GAM method requires additional measurements, but at the same time provides valuable insights about the effects of each parameter considered.
• Rapid 1D Design Method for Energy-Efficient Air Filtration Systems in Railway Stations, P.-E. Prétot, C. Schulz, D. Chalet, J. Migaud, M. Bogdan, Environments, 12/2025, [DOI]
  • Abstract

    Microscopic Particulate Matter (PM) below 10 µm can enter the respiratory system and affect human health in the short and long term. Railway enclosures are sites with high concentrations of fine PM and technical solutions like mechanical filtration exist to increase the air quality. However, several crucial factors must be evaluated and optimized like energy consumption, maintenance cost/interval, design and control. A fast and adaptable evaluation of decontamination solutions is required to find the optimal solution. To answer this, a 1D multizone model based on station discretization aligned with the track direction is proposed to precisely place decontamination systems along the station. In each zone, a set of ordinary differential equations is used to forecast the daily progression of PM concentrations, based on physical parameters (air and train velocities, and train traffic) used to describe the different physical phenomena (resuspension, deposition, ventilation and generation). Three-dimensional CFD (Computational Fluid Dynamics) simulations are used to characterize the efficiency and range of decontamination products and reproduce their effect in the 1D model. This approach allows for flexible optimization of local and global decontamination efficiencies with multiple parameter changes. PM10 and PM2.5 (below 10 and 2.5 µm) are studied here as they are often monitored.
• A novel method for establishing typical daily profile of PM concentrations in underground railway stations , V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, Indoor Environments, 2024 [DOI]
  • Abstract

    The air quality in underground railway stations (URS) poses a significant public health concern due to extremely high concentrations of particulate matter: PM10 and PM2.5. Indeed, PM sources are strong and numerous, such as train braking and tunnel effect and URS are often confined spaces with low air change rates. Despite multiple PM measurements within URS, the variability of those concentrations from stations to stations is still poorly understood. We present here a methodology for establishing a daily profile of particle mass concentrations, based on a 5-year long measurement series in a Parisian URS. This approach incorporates an extensive data cleaning process based on the identification of URS operation periods and physically inconsistent or mathematically aberrant data, together with a linear regression model. This methodology delivers three usable outcomes: a typical profile for weekdays, a typical profile for weekends, and a PM concentration Daily Amplitude Coefficient (DAC) for the considered period. The DAC is a daily metric of the pollution levels, that enables the analysis of temporal trends and facilitates the comparison with other data with other acquisition frequency. The methodology developed here in a specific URS for PM10 measurements can be easily applied to different particle size fractions or to other measured parameters exhibiting a daily profile. Weekdays PM10 concentrations exhibit two distinct peaks corresponding to morning and evening rush hours, with an average daytime concentration of 193 µg/m³. These peaks are delayed by ∼1 hour compared to the train traffic. Weekends show consistently lower PM levels with no observable peaks, averaging 157 µg/m³ during the day. Our analysis reveals the long-term temporal evolution of PM concentration within the URS, highlighting seasonal patterns with higher PM10 concentrations observed in summer (up to 400 µg/m3) and lower values in winter (down to 250 µg/m3). This indoor seasonal evolution is not correlated with the outdoor temporal evolution, showing higher concentrations during the winter. Furthermore, our results show that the optimal period (DAC∼1) for conducting experiments to obtain reliable profiles is during the spring months (April, May, June).
• Calcul des pressions en façade pour la ventilation naturelle dans les espaces semi-ouverts, E. Walther, A. Hubert, A. Sauvageon, M. Bogdan, Editions T.I., 2020, [Access]
  • Abstract

    Le renouvellement d’air est un facteur déterminant du comportement thermique dynamique dans les bâtiments ventilés naturellement ou les espaces semi-ouverts comme les gares. Cependant, dans les approches classiques de modélisation, les pressions en façade sont généralement données par des corrélations simplifiées, fonction de l’angle d’incidence et de la forme du bâtiment, qui s’avèrent inadaptées à la plupart des situations réelles. On se propose ici de donner la méthode et les bonnes pratiques permettant de déterminer de manière idoine les conditions aux limites en pression pour la simulation thermique dynamique, en utilisant la mécanique des fluides numérique. Les écarts obtenus en fonction de la discrétisation angulaire et de la rose des vents du site sont également présentés.
• A novel approach for the modelling of air quality dynamics in underground railway stations, E. Walther, M. Bogdan, Transportation Research Part D: Transport and Environment, 2017, [DOI]
  • Abstract

    This study presents an attempt of predictive modelling of airborne particulate matter in underground railway stations. The aerosol is represented by a set of simple, ordinary differential equations that describe apparent emission of two particles size-classes in relation with train traffic, ventilation and deposition. The parameters of the equations are identified numerically by a genetic algorithm and comply with their respective expected order of magnitude. A quantitative comparison of numerical results with experimental data from Paris underground station exhibits a good accordance. A qualitative comparison with results from the literature also supports the model
• Modelling of airborne particulate matter concentration in underground stations using a two size-class conservation model, E. Walther, M. Bogdan, R. Cohen, Science of The Total Environment, 2017, [DOI]
  • Abstract

    This study presents an attempt of predictive modelling of airborne particulate matter in underground railway stations. The aerosol is represented by a set of simple, ordinary differential equations that describe apparent emission of two particles size-classes in relation with train traffic, ventilation and deposition. The parameters of the equations are identified numerically by a genetic algorithm and comply with their respective expected order of magnitude. A quantitative comparison of numerical results with experimental data from Paris underground station exhibits a good accordance. A qualitative comparison with results from the literature also supports the model.
• Effective Permeability and Transfer Properties in Fractured Porous Media, G. Rastiello, R. Bennacer, G. Nahas, M. Bogdan, Defect and Diffusion Forum 362 (Fluid Flow, Energy Transfer and Design), 2015, [DOI]
  • Abstract

    Mesoscale analyses of cracked porous volumes are performed. The fluid flows through a multiphase volume comprising one macro-crack, macro-pores and random micro-porous solid inclusions. Mesostructures are defined by thresholding of spatially correlated Gaussian random fields.Transport through macropores and crack, as well as the diffusion in micro-porous solid inclusions, are taken into account. Homogeneous (without cracks) porous volumes illustrated the asymptotical behaviors. The corresponding macroscopic permeability tensors are obtained and correlated with the geometrical/statistical properties of the analyzed porous systems. A new equivalent electrical scheme, including shunt resistance, is proposed to evaluate the apparent diffusion coefficient. Macro-cracked porous volumes are then investigated.The increases in mass flux due to the crack, as well as the mass/energy exchanges with the surrounding porous medium, are quantified by direct numerical simulation. A drying region due to the macrocrack was illustrated and the corresponding apparent permeability was identified. For different geometrical configurations (macro-porosity, micro-porosity, macro-crack orientation and aperture) we quantify the macropore –crack interlink by comparing such structure with structure without possible flow between the macro-crack and the porous structure.The equivalence scheme between mass flow in cracked porous media and heat flow in porous media was underlined.
• Cement Paste Morphologies and effective diffusivity: using the Lattice Boltzmann Method, E. Walther, M. Bogdan, R. Bennacer, C. Desa, European Journal of Civil and Environmental Engineering, 2015, [DOI]
  • Abstract

    A novel explicit modelling framework based upon correlated random field and level-set methods is presented and applied to cement paste hydration. Focus is then made on effective diffusive properties prediction through numerical homogenisation, using the Lattice Boltzmann method, exploring the stability limits and performance of this method for heterogeneous media.

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Conferences

• AbriCoCoDA: A Novel Approach to Urban Heat Mitigation Through Bio-Analogous Climate Shelters, T. Gresse, D. David, F. Lefevre, M. Galtier, M. Bogdan, M. Salles, M. Picazo Guerrero, Y. Sun, E. Morlé, K. Lapray, 12th International Conference on Urban Climate, 2025, Rotterdam, Netherlands [Presentation]

• A novel method for establishing typical profile of PM concentrations in underground railway stations, V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, Indoor Air 2024, Honolulu, Hawai, USA [Full-text]

• Evaluation of the effectiveness of filtration systems in Parisian underground railway stations, V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, Indoor Air 2024, Honolulu, Hawai, USA [Poster]

• Daily PM₁₀ concentration profiles in some Parisian railway stations, V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, Indoor Air 2024, Honolulu, Hawai, USA [Poster]

• La distribution de Weibull, un outil utile ou dépassé ? Application au confort au vent, M. Bogdan, E. Walther, A. Hubert, IBPSA 2024 France, La Rochelle - Oléron, France [Full-text]

• Contribution solaire au bilan thermique du corps humain : un modèle anisotropique simplifié, E. Walther, M. Bogdan, IBPSA 2024 France, La Rochelle - Oléron, France [Full-text]

• Profils types journaliers des concentrations en particules dans les enceintes ferroviaires souterraines parisiennes, V. Rakotonirinjanahary, S. Crumeyrolle, M. Bogdan, B. Hanoune, 37^ème Congrès français sur les aérosols, 2024, Paris, France, [Abstract]

• Calcul des facteurs de forme entre polygones - Application à la thermique urbaine et aux études de confort, M. Bogdan, E. Walther, M. Alecian, M. Chapon, IBPSA France 2022, Châlons-en-Champagne, France, [Full-text]

• Fast Method to Design Air Filtration Solution at Low Energy Cost in Subterranean Train Stations, P.-E. Pretot, C. Schulz, D. Chalet, J. Migaud, M. Bogdan, 7th World Congress on Civil, Structural, and Environmental Engineering (CSEE’2022), Lisbon, Portugal [Full-text]

• Spatial distribution of thermal comfort: A case study in Paris’ station, E. Walther, M. Bogdan, F. Devys-Peyre, C. Inard, BS 2021 17th IBPSA international conference, Brugges, Belgium, [Full-text]

• Détermination des conditions limites en pression pour le calcul de la ventilation naturelle, E. Walther, A. Hubert, A. Sauvageon, M. Bogdan, IBPSA 2021 France, online, [Full-text]

• Improving the prediction of natural ventilation by coupling CFD and BES: A case study in Strasbourg train station, E. Walther, A. Hubert, A. Sauvageon, M. Bogdan, BS 2019: 16th IBPSA international conference, Rome, Italy

• Simulation of the piston effect of a train entering or leaving an underground station., S. Aguinaga, M. Bogdan, A. Sauvageon, 2017, 3rd French/Belgian OpenFOAM® users conference, Valenciennes, France, [Full-text]

• A Novel Approach For The Modelling Of Air Quality Dynamics In Underground Railway Stations, E. Walther, M. Bogdan, Air Pollution 2017, Cadiz, Spain, [http://dx.doi.org/10.2495/EI-V1-N2-79-87]

• Prediction of airborne particulate matter concentration in underground stations using a two size class conservation model, E. Walther, M. Bogdan, R. Cohen, Healthy Buildings 2017 Europe, Lublin, Poland [Full-text]

• Microscopic model for concrete diffusivity prediction, M. Bogdan, F. Benboudjema, J.-B. Colliat, L. Stefan, EURO-C 2014: Computational Modelling of Concrete and Concrete Structures, Sankt Anton am Arlberg, Austria, [http://dx.doi.org/10.1201/b16645-75]

• Modèle morphologique d’hydratation & Methodes level-set, M. Bogdan, J.-B. Colliat, F. Benboudjema, L. Stefan, AUGC 2014, Orléans, France

• Modélisation des transferts diffusifs dans les matériaux cimentaires , M. Bogdan, F. Benboudjema, J.-B. Colliat, L. Stefan, AUGC 2013, Cachan, France, [Full-text]

• Morphological modeling of cement based materials and hydration process, M. Bogdan, E. Roubin, J.-B. Colliat, F. Benboudjema, L. Stefan, Microdurability 2012 - Amsterdam, The Netherlands, [http://dx.doi.org/10.13140/2.1.4620.8007]

• Modélisation des transferts de masse dans les matériaux à matrice cimentaire à l’aide d’un modèle morphologique, M. Bogdan, E. Roubin, J.-B. Colliat, F. Benboudjema, L. Stefan, Transfert 2012, Lille, France

• Multiscale Failure for Heterogeneous Materials: Link with Morphological Modeling, E. Roubin, M. Bogdan, J.-B. Colliat, COMPLAS XI, 2011, Barselone, Spain, [Full-text]

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Technical

• Comfort modelling in semi-outdoor spaces, E. Walther, M. Bogdan, REHVA European HVAC Journal, 2017, [Full-text]

• Natural ventilation uncertainties in building energy simulations, M. Bogdan, E. Walther, REHVA European HVAC Journal, 2017, [Full-text]

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