| Lintermann, Andreas; Schröder, Wolfgang Lattice–Boltzmann simulations for complex geometries on high-performance computers Artikel In: CEAS Aeronautical Journal, 2020, ISBN: 1869-5582. @article{Lintermann2020c,
title = {Lattice–Boltzmann simulations for complex geometries on high-performance computers},
author = {Lintermann, Andreas and Schröder, Wolfgang },
url = {http://link.springer.com/10.1007/s13272-020-00450-1},
doi = {10.1007/s13272-020-00450-1},
isbn = {1869-5582},
year = {2020},
date = {2020-05-13},
journal = {CEAS Aeronautical Journal},
abstract = {Complex geometries pose multiple challenges to the field of computational fluid dynamics. Grid generation for intricate objects is often difficult and requires accurate and scalable geometrical methods to generate meshes for large-scale computations. Such simulations, furthermore, presume optimized scalability on high-performance computers to solve high-dimensional physical problems in an adequate time. Accurate boundary treatment for complex shapes is another issue and influences parallel load-balance. In addition, large serial geometries prevent efficient computations due to their increased memory footprint, which leads to reduced memory availability for computations. In this paper, a framework is presented that is able to address the aforementioned problems. Hierarchical Cartesian boundary-refined meshes for complex geometries are obtained by a massively parallel grid generator. In this process, the geometry is parallelized for efficient computation. Simulations on large-scale meshes are performed by a high-scaling lattice–Boltzmann method using the second-order accurate interpolated bounce-back boundary conditions for no-slip walls. The method employs Hilbert decompositioning for parallel distribution and is hybrid MPI/OpenMP parallelized. The parallel geometry allows to speed up the pre-processing of the solver and massively reduces the local memory footprint. The efficiency of the computational framework, the application of which to, e.g., subsonic aerodynamic problems is straightforward, is shown by simulating clearly different flow problems such as the flow in the human airways, in gas diffusion layers of fuel cells, and around an airplane landing gear configuration},
keywords = {Airway, Computational Fluid Dynamics, High performance computing, Large-Scale Simulation Data, Lattice-Boltzmann method},
pubstate = {published},
tppubtype = {article}
}
Complex geometries pose multiple challenges to the field of computational fluid dynamics. Grid generation for intricate objects is often difficult and requires accurate and scalable geometrical methods to generate meshes for large-scale computations. Such simulations, furthermore, presume optimized scalability on high-performance computers to solve high-dimensional physical problems in an adequate time. Accurate boundary treatment for complex shapes is another issue and influences parallel load-balance. In addition, large serial geometries prevent efficient computations due to their increased memory footprint, which leads to reduced memory availability for computations. In this paper, a framework is presented that is able to address the aforementioned problems. Hierarchical Cartesian boundary-refined meshes for complex geometries are obtained by a massively parallel grid generator. In this process, the geometry is parallelized for efficient computation. Simulations on large-scale meshes are performed by a high-scaling lattice–Boltzmann method using the second-order accurate interpolated bounce-back boundary conditions for no-slip walls. The method employs Hilbert decompositioning for parallel distribution and is hybrid MPI/OpenMP parallelized. The parallel geometry allows to speed up the pre-processing of the solver and massively reduces the local memory footprint. The efficiency of the computational framework, the application of which to, e.g., subsonic aerodynamic problems is straightforward, is shown by simulating clearly different flow problems such as the flow in the human airways, in gas diffusion layers of fuel cells, and around an airplane landing gear configuration |
| Kim, Soo-Yeon; Park, Young-Chel; Lee, Kee-Joon; Lintermann, Andreas; Han, Sang-Sun; Yu, Hyung-Seog; Choi, Yoon Jeong Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults Artikel In: The Angle Orthodontist, S. 092917–656.1, 2018, ISSN: 0003-3219. @article{Kim2018,
title = {Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults},
author = {Kim, Soo-Yeon and Park, Young-Chel and Lee, Kee-Joon and Lintermann, Andreas and Han, Sang-Sun and Yu, Hyung-Seog and Choi, Yoon Jeong},
editor = {The Angle Orthodontist},
url = {https://rhinodiagnost.eu/wp-content/uploads/2018/04/092917-656.1_Kim2018.pdf},
doi = {www.angle.org/doi/10.2319/092917-656.1},
issn = {0003-3219},
year = {2018},
date = {2018-03-23},
journal = {The Angle Orthodontist},
pages = {092917--656.1},
abstract = {Objectives: To evaluate changes in the volume and cross-sectional area of the nasal airway before and 1 year after nonsurgical miniscrew-assisted rapid maxillary expansion (MARME) in young adults.
Materials and Methods: Fourteen patients (mean age, 22.7 years; 10 women, four men) with a transverse discrepancy who underwent cone beam computed tomography before (T0), immediately after (T1), and 1 year after (T2) expansion were retrospectively included in this study. The volume of the nasal cavity and nasopharynx and the cross-sectional area of the anterior, middle, and posterior segments of the nasal airway were measured and compared among the three timepoints using paired t-tests.
Results: The volume of the nasal cavity showed a significant increase at T1 and T2 (P < .05), while that of the nasopharynx increased only at T2 (P < .05). The anterior and middle cross-sectional areas significantly increased at T1 and T2 (P < .05), while the posterior cross-sectional area showed no significant change throughout the observation period (P > .05).
Conclusions: The results demonstrate that the volume and cross-sectional area of the nasal cavity increased after MARME and were maintained at 1 year after expansion. Therefore, MARME may be helpful in expanding the nasal airway.
},
keywords = {Airway, MARME, Nasal cavity flows, Nasal respiration, Respiratory Flow Computation},
pubstate = {published},
tppubtype = {article}
}
Objectives: To evaluate changes in the volume and cross-sectional area of the nasal airway before and 1 year after nonsurgical miniscrew-assisted rapid maxillary expansion (MARME) in young adults.
Materials and Methods: Fourteen patients (mean age, 22.7 years; 10 women, four men) with a transverse discrepancy who underwent cone beam computed tomography before (T0), immediately after (T1), and 1 year after (T2) expansion were retrospectively included in this study. The volume of the nasal cavity and nasopharynx and the cross-sectional area of the anterior, middle, and posterior segments of the nasal airway were measured and compared among the three timepoints using paired t-tests.
Results: The volume of the nasal cavity showed a significant increase at T1 and T2 (P < .05), while that of the nasopharynx increased only at T2 (P < .05). The anterior and middle cross-sectional areas significantly increased at T1 and T2 (P < .05), while the posterior cross-sectional area showed no significant change throughout the observation period (P > .05).
Conclusions: The results demonstrate that the volume and cross-sectional area of the nasal cavity increased after MARME and were maintained at 1 year after expansion. Therefore, MARME may be helpful in expanding the nasal airway.
|