@article{MTMT:34742505,
	title = {Statistical assessment of the concentration fluctuations in street canyons via time-resolved wind tunnel experiments},
	url = {https://m2.mtmt.hu/api/publication/34742505},
	author = {Papp, Bálint and Istók, Balázs and Koren, Márton and Balczó, Márton and Kristóf, Gergely},
	doi = {10.1016/j.jweia.2024.105665},
	journal-iso = {J WIND ENG IND AEROD},
	journal = {JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS},
	volume = {246},
	unique-id = {34742505},
	issn = {0167-6105},
	abstract = {Time-resolved wind tunnel experiments are performed for three periodic street canyon configurations: one of uniform (H/W = 1) and two of variable building height (consisting of 0.5H and 1.5H tall towers in aligned and staggered arrangements) for perpendicular wind direction. The velocity field is mapped using Laser Doppler Anemometry (LDA), and the tracer gas concentration is sampled using Fast Flame Ionization Detection (FFID). The concentration field is characterized by the mean concentration and the characteristic percentiles of the concentration-time series, such as the median and the peak, represented by the 99th percentile, in a total of 1138 sampling points. The probability distribution of the concentration in each point is modeled using the gamma distribution, which is fitted based on the mean and the variance of the measured time series. The results show that the mean pedestrian exposure to air pollutants is significantly lower in the case of heterogeneous roof height, although the mean concentration at the leeward corner of the source canyon can locally exceed those of the uniform street canyons for both tower arrangements of variable building height. Moreover, it is shown that the concentration peaks for both tower configurations can significantly exceed those of the uniform canyons case, especially near the sources. © 2024 The Authors},
	keywords = {Probability distributions; Time series; Classifiers; Gamma distribution; Gamma distribution; Air quality; Doppler effect; Anemometers; Roofs; CONCENTRATION FLUCTUATIONS; Wind tunnels; Urban air quality; Urban air quality; Non-uniform; Wind tunnel measurements; street canyon; street canyon; concentration fluctuation; Laser doppler anemometry; Laser Doppler velocimeters; flame ionization detection; Peak concentrations; Peak concentrations; Building height; Fast Flame Ionization Detection (FFID); Laser Doppler Anemometry (LDA); Non-uniform building height; Variable roof height; Wind tunnel measurement; Fast flame ionization detection; Laser dopple anemometry; Non-uniform building height; Variable roof height},
	year = {2024},
	eissn = {1872-8197},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Istók, Balázs/0000-0002-0248-0074; Balczó, Márton/0000-0002-1273-3047; Kristóf, Gergely/0000-0001-7572-6875}
}

@article{MTMT:34495646,
	title = {Predicting Concentration Fluctuations of Locally Emitted Air Pollutants in Urban-like Geometry Using Deep Learning},
	url = {https://m2.mtmt.hu/api/publication/34495646},
	author = {Papp, Bálint and Kristóf, Gergely},
	doi = {10.3311/PPme.23391},
	journal-iso = {PERIOD POLYTECH MECH ENG},
	journal = {PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING},
	volume = {68},
	unique-id = {34495646},
	issn = {0324-6051},
	abstract = {The accurate quantification of concentration fluctuations is crucial when evaluating the exposure to toxic, infectious, reactive, flammable, or explosive substances, as well as for the estimation of odor nuisance. However, in the field of Computational Fluid Dynamics (CFD), the industry currently relies predominantly on steady-state RANS turbulence models for simulating near-field pollutant dispersion, which are only capable of producing the time-averaged concentration field. This paper presents a regression relationship for calculating the standard deviation of the local concentration based on the mean concentration and the downstream distance from a point source, over a city-like surface, in the case of the wind direction perpendicular to the streets. The desired peak values and other statistical characteristics can be predicted by assuming a gamma distribution which is fitted based on the average and standard deviation. To obtain the regression function, a deep neural network model was used. The model was trained using time-resolved concentration data obtained from wind tunnel experiments. The validation results show that the concentration fluctuations predicted by the DNN-based model are in satisfactory agreement with the measurement data in terms of the skewness, the kurtosis, the median, and the peak concentrations. Furthermore, the present paper suggests a workflow for estimating the concentration fluctuations based on RANS CFD results, as well as recommendations for generating further training data for specific applications.},
	keywords = {simulation; Environment; dispersion; fluid dynamics; CFD; Urban air quality},
	year = {2024},
	eissn = {1587-379X},
	pages = {44-52},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Kristóf, Gergely/0000-0001-7572-6875}
}

@inproceedings{MTMT:34499886,
	title = {Mezoskálás hatások szerepe az áramlási térre és a terjedésre explicit érdességi rétegben},
	url = {https://m2.mtmt.hu/api/publication/34499886},
	author = {Koren, Márton and Kristóf, Gergely},
	booktitle = {XXVI. Tavaszi Szél Konferencia 2023},
	unique-id = {34499886},
	year = {2023},
	pages = {501-519},
	orcid-numbers = {Kristóf, Gergely/0000-0001-7572-6875}
}

@article{MTMT:33702898,
	title = {Investigation of the accuracy of the transient wind forcing model applied for a shear-driven LES},
	url = {https://m2.mtmt.hu/api/publication/33702898},
	author = {Koren, Márton and Kristóf, Gergely},
	doi = {10.1016/j.jweia.2023.105363},
	journal-iso = {J WIND ENG IND AEROD},
	journal = {JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS},
	volume = {236},
	unique-id = {33702898},
	issn = {0167-6105},
	abstract = {We examine the effectiveness of the Transient Wind Forcing (TWF), previously validated with field and wind tunnel experiments, using LES in large-scale and small-scale cyclic domains. The small domain includes only a part of the atmospheric boundary-layer height, so the effect of wind shear is modeled near its upper boundary with the TWF coupling method. It is essentially a time-dependent volume source of momentum, which is controlled using velocity time series extracted from a point in the large domain. Surface roughness is explicitly modeled in both domains. The dispersion of atmospheric pollutants is investigated by the Lagrange method. The model error of TWF coupling is quantitatively evaluated in the case of atmospheric boundary layers with different Coriolis parameters, atmospheric stability, and surface roughness. The results of the small model driven by the TWF method showed good agreement with the reference results obtained from the large domain based on the average wind speed and turbulence profiles between and directly above the buildings, as well as the concentration of air pollutants emitted at ground level. For this, it was also necessary to consider the pressure gradient corresponding to the geostrophic wind and the effect of the Coriolis force in the small domain.},
	year = {2023},
	eissn = {1872-8197},
	orcid-numbers = {Kristóf, Gergely/0000-0001-7572-6875}
}

@{MTMT:33120024,
	title = {Transient Wind Forcing: a method for modelling wind shear in building-scale Large Eddy Simulations},
	url = {https://m2.mtmt.hu/api/publication/33120024},
	author = {Koren, Márton and Balogh, Miklós and Kristóf, Gergely},
	booktitle = {PHYSMOD 2022 - International Workshop on Physical Modeling of Flow and Dispersion Phenomena},
	unique-id = {33120024},
	year = {2022},
	pages = {111-111},
	orcid-numbers = {Kristóf, Gergely/0000-0001-7572-6875}
}

@inproceedings{MTMT:33113557,
	title = {Statistical assessment of the ventilation of street canyons based on time-resolved wind tunnel experiments},
	url = {https://m2.mtmt.hu/api/publication/33113557},
	author = {Papp, Bálint and Istók, Balázs and Koren, Márton and Balczó, Márton and Kristóf, Gergely},
	booktitle = {PHYSMOD 2022 - International Workshop on Physical Modeling of Flow and Dispersion Phenomena},
	unique-id = {33113557},
	year = {2022},
	pages = {143-155},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Istók, Balázs/0000-0002-0248-0074; Balczó, Márton/0000-0002-1273-3047; Kristóf, Gergely/0000-0001-7572-6875}
}

@inproceedings{MTMT:33113416,
	title = {Building Patterns Favorable for Air Quality: A Parameter Study Using LES},
	url = {https://m2.mtmt.hu/api/publication/33113416},
	author = {Papp, Bálint and Kristóf, Gergely},
	booktitle = {Proceedings of Conference on Modelling Fluid Flow (CMFF'22)},
	unique-id = {33113416},
	year = {2022},
	pages = {438-451},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Kristóf, Gergely/0000-0001-7572-6875}
}

@inproceedings{MTMT:33108564,
	title = {Mechanistic turbulence: Targeted energy transfer in a multi-degree-of-freedom nonlinear oscillator},
	url = {https://m2.mtmt.hu/api/publication/33108564},
	author = {Bak, Bendegúz Dezső and Rochlitz, Róbert Zoltán and Kalmár-Nagy, Tamás and Kristóf, Gergely},
	booktitle = {Proceedings of Conference on Modelling Fluid Flow (CMFF'22)},
	unique-id = {33108564},
	year = {2022},
	pages = {357-364},
	orcid-numbers = {Bak, Bendegúz Dezső/0000-0003-1378-875X; Kalmár-Nagy, Tamás/0000-0003-1374-2620; Kristóf, Gergely/0000-0001-7572-6875}
}

@CONFERENCE{MTMT:32893885,
	title = {The role of thermal convection in the dispersion of traffic-induced air pollutants in the Urban environment},
	url = {https://m2.mtmt.hu/api/publication/32893885},
	author = {Papp, Bálint and Kristóf, Gergely},
	booktitle = {20th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes},
	unique-id = {32893885},
	year = {2021},
	pages = {1-5},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Kristóf, Gergely/0000-0001-7572-6875}
}

@article{MTMT:32128267,
	title = {Application and assessment of a GPU-based LES method for predicting dynamic wind loads on buildings},
	url = {https://m2.mtmt.hu/api/publication/32128267},
	author = {Papp, Bálint and Kristóf, Gergely and Gromke, Christof},
	doi = {10.1016/j.jweia.2021.104739},
	journal-iso = {J WIND ENG IND AEROD},
	journal = {JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS},
	volume = {217},
	unique-id = {32128267},
	issn = {0167-6105},
	year = {2021},
	eissn = {1872-8197},
	orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Kristóf, Gergely/0000-0001-7572-6875}
}