@article{MTMT:2692479,
	title = {Sensitivity analysis of microscale obstacle resolving models for an idealized Central European city center, Michel-Stadt},
	url = {https://m2.mtmt.hu/api/publication/2692479},
	author = {Rákai, Anikó and Kristóf, Gergely and Franke, Jörg},
	journal-iso = {IDŐJÁRÁS},
	journal = {IDŐJÁRÁS / QUARTERLY JOURNAL OF THE HUNGARIAN METEOROLOGICAL SERVICE},
	volume = {118},
	unique-id = {2692479},
	issn = {0324-6329},
	abstract = {Microscale meteorological models with obstacle resolving grids are an important part of air quality and emergency response models in urban areas providing the flow field for the dispersion model. The buildings as bluff bodies are challenging from the discretization point of view and have an effect on the quality of the results. In engineering communities the same topic has emerged, called Computational Wind Engineering (CWE), using the methods of Computational Fluid Dynamics (CFD) calculating wind load on buildings, wind comfort in the urban canopy and pollutant dispersion. The goal of this paper is to investigate the sensitivity of this method to the discretization procedure used to resolve the urban canopy with meshes which are of operational size, i.e. can be run on a single powerful computer of a design office as well. To assess the quality of the results the computed mean and rms (root mean square) velocity components are compared to detailed wind tunnel results of an idealized Central European city center, Michel-Stadt. A numerical experiment is carried out where the numerical sensitivity of the solution is tested by additional solutions on different grid resolutions (at least 3 stages of grid refinement), unrelated grid types (tetrahedral, polyhedral, Cartesian hexahedral and body fitted hexahedral, all automatically generated) and different discretization schemes. For an objective qualitative judgment two metrics are investigated, the well know hit rate and another metric that do not depend on threshold values. The quality of the meshes is investigated with correspondence to the numerical stability, CPU-time need and grid quality metric. It is shown that the solution with the best resulting metric is not necessarily the most suitable for operational purposes and almost 20% difference in the hit rate metric can result from different discretization approaches.},
	keywords = {VALIDATION; FLOW; Environment; AIR-QUALITY; Buildings; CFD SIMULATION; Urban flow; microscale air quality models; obstacle resolving; polyhedral mesh; snappyHexMesh; ATMOSPHERIC BOUNDARY-LAYER},
	year = {2014},
	eissn = {0324-6329},
	pages = {53-77},
	orcid-numbers = {Kristóf, Gergely/0000-0001-7572-6875}
}