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arXiv 2025年

作者： Teutscher, Dennis Bukreev, Fedor Kummerländer, Adrian Simonis, Stephan Bächler, Peter Rezaee, Ashkan Hermansdorfer, Mariusz Krause, Mathias J. Lattice Boltzmann Research Group Karlsruhe Institute of Technology Englerstr. 2 Karlsruhe Baden-Württemberg76131 Germany Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Straße am Forum 8 Karlsruhe Baden-Württemberg76131 Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Englerstr. 2 Karlsruhe Baden-Württemberg76131 Germany Henning Larsen Vesterbrogade 76 Hovedstaden Copenhagen1620 Denmark

Digital twin (DT) technology is increasingly used in urban planning, leveraging real-time data integration for environmental monitoring. This paper presents an urban-focused DT that combines computational fluid dynamics simulations with live meteorological data to analyze pollution dispersion. Addressing the health impacts of pollutants like particulate matter and nitrogen dioxide, the DT provides real-time updates on air quality, wind speed, and direction. Using OpenStreetMap’s XML-based data, the model distinguishes between porous elements like trees and solid structures, enhancing urban flow analysis. The framework employs the lattice Boltzmann method (LBM) within the open-source software OpenLB to simulate pollution transport. Nitrogen dioxide and particulate matter concentrations are estimated based on traffic and building emissions, enabling hot-spot identification. The DT was used from November 7 to 23, 2024, with hourly updates, capturing pollution trends influenced by wind patterns. Results show that alternating east-west winds during this period create a dynamic pollution distribution, identifying critical residential exposure areas. This work contributes a novel DT framework that integrates real-time meteorological data, OpenStreetMap-based geometry, and high-fidelity LBM simulations for urban wind and pollution modeling. Unlike existing DTs, which focus on structural monitoring or large-scale environmental factors, this approach enables fine-grained, dynamic analyses of urban airflow and pollution dispersion. By allowing interactive modifications to urban geometry and continuous data updates, the DT serves as a powerful tool for adaptive urban planning, supporting evidence-based policy making to improve air quality and public health. Copyright © 2025, The Authors. All rights reserved.

关键词： Air quality

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基于SO(3)群几何精确Kirchhoff梁理论的细长梁动力学

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Acta Mechanica Sinica 2024年第4期40卷 212-225页

作者：安志朋王斌侯云森刘铖 MOE Key Laboratory of Dynamics and Control of Flight Vehicle School of Aerospace EngineeringBeijing Institute of TechnologyBeijing100081China CAEP Software Center for High Performance Numerical Simulation Beijing100088China Institute of Applied Physics and Computational Mathematics Beijing100088China

本研究旨在开发一种高效的细长梁单元,精确描述细长柔性结构的大变形和大旋转,在现有细长梁单元研究的基础上,提出一种基于SO(3)群活动标架的二阶几何精确Kirchhoff梁单元(GEKBF),用于细长梁的动力学研究.首先,在此标架中推导出运动学... 详细信息

本研究旨在开发一种高效的细长梁单元,精确描述细长柔性结构的大变形和大旋转,在现有细长梁单元研究的基础上,提出一种基于SO(3)群活动标架的二阶几何精确Kirchhoff梁单元(GEKBF),用于细长梁的动力学研究.首先,在此标架中推导出运动学描述和几何、本构和动态平衡方程及其线性化.然后,引入相对扭转角的二阶插值函数,以提高单元的收敛性,通过选择合适的标架来开发旋转矢量参数化.它可以显著减少由刚体旋转引起的几何非线性,并提高描述当前标架下单元旋转公式的计算效率.此外,考虑了参考标架的影响,并使用空间平行移动而非时间平行移动,简化了弹性力和雅可比矩阵的推导.使用李群广义α-方法求解李群上的半离散运动方程.最后,通过数值实例验证了GEKBF的准确性,包括静力学和动力学.

关键词：平行移动标架弹性力旋转矢量细长梁柔性结构半离散动态平衡

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A Digital Urban Twin Enabling Interactive Pollution Predictions and Enhanced Planning

SSRN

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SSRN 2025年

Digital twin (DT) technology is increasingly used in urban planning, leveraging real-time data integration for environmental monitoring. This paper presents an urban-focused DT that combines computational fluid dynamics simulations with live meteorological data to analyze pollution dispersion. Addressing the health impacts of pollutants like particulate matter and nitrogen dioxide, the DT provides real-time updates on air quality, wind speed, and *** OpenStreetMap’s XML-based data, the model distinguishes between porous elements like trees and solid structures, enhancing urban flow analysis. The framework employs the lattice Boltzmann method (LBM) within the open-source software OpenLB to simulate pollution transport. Nitrogen dioxide and particulate matter concentrations are estimated based on traffic and building emissions, enabling hot-spot *** DT was used from November 7 to 23, 2024, with hourly updates, capturing pollution trends influenced by wind patterns. Results show that alternating east-west winds during this period create a dynamic pollution distribution, identifying critical residential exposure *** work contributes a novel DT framework that integrates real-time meteorological data, OpenStreetMap-based geometry, and high-fidelity LBM simulations for urban wind and pollution modeling. Unlike existing DTs, which focus on structural monitoring or large-scale environmental factors, this approach enables fine-grained, dynamic analyses of urban airflow and pollution dispersion. By allowing interactive modifications to urban geometry and continuous data updates, the DT serves as a powerful tool for adaptive urban planning, supporting evidence-based policy making to improve air quality and public health. © 2025, The Authors. All rights reserved.

关键词： Air quality

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A digital urban twin enabling interactive pollution predictions and enhanced planning

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Building and Environment 2025年 281卷

作者： Teutscher, Dennis Bukreev, Fedor Kummerländer, Adrian Simonis, Stephan Bächler, Peter Rezaee, Ashkan Hermansdorfer, Mariusz Krause, Mathias J. Lattice Boltzmann Research Group Karlsruhe Institute of Technology Englerstr. 2 Baden-Württemberg Karlsruhe76131 Germany Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Straße am Forum 8 Baden-Württemberg Karlsruhe76131 Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Englerstr. 2 Baden-Württemberg Karlsruhe76131 Germany Henning Larsen Vesterbrogade 76 Hovedstaden Copenhagen1620 Denmark

Digital twin (DT) technology is increasingly used in urban planning, leveraging real-time data integration for environmental monitoring. This paper presents an urban-focused DT that combines computational fluid dynamics simulations with live meteorological data to analyze pollution dispersion. Addressing the health impacts of pollutants like particulate matter and nitrogen dioxide, the DT provides real-time updates on air quality, wind speed, and direction. Using OpenStreetMap's XML-based data, the model distinguishes between porous elements like trees and solid structures, enhancing urban flow analysis. The framework employs the lattice Boltzmann method (LBM) within the open-source software OpenLB to simulate pollution transport. Nitrogen dioxide and particulate matter concentrations are estimated based on traffic and building emissions, enabling hot-spot identification. The DT was used from November 7 to 23, 2024, with hourly updates, capturing pollution trends influenced by wind patterns. Results show that alternating east–west winds during this period create a dynamic pollution distribution, identifying critical residential exposure areas. This work contributes a novel DT framework that integrates real-time meteorological data, OpenStreetMap-based geometry, and high-fidelity LBM simulations for urban wind and pollution modeling. Unlike existing DTs, which focus on structural monitoring or large-scale environmental factors, this approach enables fine-grained, dynamic analyses of urban airflow and pollution dispersion. By allowing interactive modifications to urban geometry and continuous data updates, the DT serves as a powerful tool for adaptive urban planning, supporting evidence-based policy making to improve air quality and public health. © 2025 The Author(s)

关键词： Air quality

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Multi-Scale Electromagnetic Simulation Through Parallel Adaptive Mesh Refinement FDTD Method with Symmetric Positive Semi-Definite Subgridding Scheme

Multi-Scale Electromagnetic Simulation Through Parallel Adap...

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2023 International applied Computational Electromagnetics Society Symposium, ACES-China 2023

作者： Li, Hanyu Zhou, Haijing Bao, Xianfeng Chen, Xiaojie School of Physical Science and Technology Southwest Jiaotong University Chengdu China Institute of Applied Physics and Computational Mathematics Beijing China Software Center for High Performance Numerical Simulation Caep Beijing China

ISBN: (纸本)9781733509657

FDTD method is a common approach for electromagnetic propagation, scattering and coupling simulation. Conventional FDTD with universal mesh requires numerous computations to represent solve problems with multi-scale structures. In this paper, adaptive mesh refinement (AMR) strategy is performed to reduce the calculations along with symmetric positive semi-definite subgridding scheme to guarantee stability. numerical example of a missile seeker coupling simulation shows that the computation time decrease down to 2% while preserving excellent precision. © 2023 applied Computational Electromagnetics Society (ACES).

关键词： Finite difference time domain method

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AN ALGEBRAIC MULTISCALE METHOD FOR SPATIAL NETWORK MODELS

arXiv

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arXiv 2023年

作者： Hauck, Moritz Maier, Roland Målqvist, Axel Department of Mathematical Sciences Chalmers University of Technology University of Gothenburg Göteborg41296 Sweden Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Englerstr. 2 Karlsruhe76131 Germany

In this work, we present a multiscale approach for the reliable coarse-scale approximation of spatial network models represented by a linear system of equations with respect to the nodes of a graph. The method is based on the ideas of the Localized Orthogonal Decomposition (LOD) strategy and is constructed in a fully algebraic way. This allows to apply the method to geometrically challenging objects such as corrugated cardboard. In particular, the method can also be applied to finite difference or finite element discretizations of elliptic partial differential equations, yielding an approximation with similar properties as the LOD in the continuous setting. We present a rigorous error analysis of the proposed method under suitable assumptions on the network. Moreover, numerical examples are presented that underline our theoretical *** Codes 05C50, 35R02, 65N12, 65N15, 65N30, 90C35 © 2023, CC BY-NC-SA.

关键词： Linear systems

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POTENTIAL FOR DAMAGE TO FRUITS DURING TRANSPORT THROUGH CROSS-SECTION CONSTRICTIONS

arXiv

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arXiv 2024年

作者： Marquardt, Jan E. Eysel, Bastian Sadric, Martin Rauh, Cornelia Krause, Mathias J. Lattice Boltzmann Research Group Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Karlsruhe76131 Germany Institute of Food Biotechnology and Food Process Engineering Faculty III Process Sciences Technische Universität Berlin Berlin10623 Germany Lattice Boltzmann Research Group Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Karlsruhe76131 Germany

Fruit preparations are used in various forms in the food industry. For example, they are used as an ingredient in dairy products such as yogurt with added fruit. The dispersed fruit pieces can be described as soft particles with viscoelastic material behavior. The continuous phase is represented by fluids with complex flow behavior depending on the formulation. Characterization has shown that this can be described by the Herschel-Bulkley model. Since damage to fruit pieces is undesirable in industrial transport processes, the potential for damage to fruit pieces during transport of pipes in cross-sectional constrictions is analyzed. The analysis is performed numerically using the homogenized lattice Boltzmann method and validated by an experiment on industrial fruit preparations at pilot plant scale. The results show a strong dependence of the damage potential on the (local) Metzner-Reed Reynolds number. Copyright © 2024, The Authors. All rights reserved.

关键词： Fruits

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Maximizing the electromagnetic chirality of thin metallic nanowires at optical frequencies

arXiv

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arXiv 2022年

作者： Fernandez-Corbaton, Ivan Griesmaier, Roland Knöller, Marvin Rockstuhl, Carsten Institute of Nanotechnology Karlsruhe Institute of Technology Karlsruhe76021 Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Karlsruhe76131 Germany Institute of Theoretical Solid State Physics Karlsruhe Institute of Technology Karlsruhe76131 Germany

Electromagnetic waves impinging on three-dimensional helical metallic metamaterials have been shown to exhibit chiral effects of large magnitude both theoretically and in experimental realizations. Chirality here describes different responses of scatterers, materials, or metamaterials to left and right circularly polarized electromagnetic waves. These differences can be quantified in terms of electromagnetic chirality measures. In this work we consider the optimal design of thin metallic free-form nanowires that possess measures of electromagnetic chirality as large as fundamentally possible. We focus on optical frequencies and use a gradient based optimization scheme to determine the optimal shape of highly chiral thin silver and gold nanowires. The electromagnetic chirality measures of our optimized nanowires exceed that of traditional metallic helices. Therefore, these should be well suited as building blocks of novel metamaterials with an increased chiral response. We discuss a series of numerical examples, and we evaluate the performance of different optimized *** Codes 78M50, (49Q10, 78A45) Copyright © 2022, The Authors. All rights reserved.

关键词： Shape optimization

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A LOCALIZED ORTHOGONAL DECOMPOSITION STRATEGY FOR HYBRID DISCONTINUOUS GALERKIN METHODS

arXiv

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arXiv 2023年

作者： Lu, Peipei Maier, Roland Rupp, Andreas Department of Mathematics Sciences Soochow University Suzhou215006 China Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Englerstr. 2 Karlsruhe76131 Germany Department of Mathematics Saarland University Saarbrücken66123 Germany

We formulate and analyze a multiscale method for an elliptic problem with an oscillatory coefficient based on a skeletal (hybrid) formulation. More precisely, we employ hybrid discontinuous Galerkin approaches and combine them with the localized orthogonal decomposition methodology to obtain a coarse-scale skeletal method that effectively includes fine-scale information. This work is the first step in reliably merging hybrid skeletal formulations and localized orthogonal decomposition to unite the advantages of both strategies. numerical experiments are presented to illustrate the theoretical *** Codes 65N12, 65N30 Copyright © 2023, The Authors. All rights reserved.

关键词： Galerkin methods

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HOMOGENIZED LATTICE BOLTZMANN METHODS FOR FLUID FLOW THROUGH POROUS MEDIA – PART I: KINETIC MODEL DERIVATION

arXiv

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arXiv 2023年

作者： Simonis, Stephan Hafen, Nicolas Jeßberger, Julius Dapelo, Davide Thäter, Gudrun Krause, Mathias J. Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Karlsruhe76131 Germany Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Karlsruhe76131 Germany Lattice Boltzmann Research Group Karlsruhe Institute of Technology Karlsruhe76131 Germany School of Engineering University of Liverpool LiverpoolL69 3BX United Kingdom

In this series of studies, we establish homogenized lattice Boltzmann methods (HLBM) for simulating fluid flow through porous media. Our contributions in part I are twofold. First, we assemble the targeted partial differential equation system by formally unifying the governing equations for nonstationary fluid flow in porous media. A matrix of regularly arranged, equally sized obstacles is placed into the domain to model fluid flow through porous structures governed by the incompressible nonstationary Navier–Stokes equations (NSE). Depending on the ratio of geometric parameters in the matrix arrangement, several homogenized equations are obtained. We review existing methods for homogenizing the nonstationary NSE for specific porosities and discuss the applicability of the resulting model equations. Consequently, the homogenized NSE are expressed as targeted partial differential equations that jointly incorporate the derived aspects. Second, we propose a kinetic model, the homogenized Bhatnagar–Gross–Krook Boltzmann equation, which approximates the homogenized nonstationary NSE. We formally prove that the zeroth and first order moments of the kinetic model provide solutions to the mass and momentum balance variables of the macrocopic model up to specific orders in the scaling parameter. Based on the present contributions, in the sequel (part II), the homogenized NSE are consistently approximated by deriving a limit consistent HLBM discretization of the homogenized Bhatnagar–Gross–Krook Boltzmann *** Codes 35Q30, 35Q20, 35B27 Copyright © 2023, The Authors. All rights reserved.

关键词： Porous materials

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