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Accuracy and performance of the lattice Boltzmann method with 64-bit, 32-bit, and customized 16-bit number formats

Physical Review E 2022年第1期106卷 015308-015308页

作者： Moritz Lehmann Mathias J. Krause Giorgio Amati Marcello Sega Jens Harting Stephan Gekle Biofluid Simulation and Modeling–Theoretische Physik VI University of Bayreuth Bayreuth Germany Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Karlsruhe Germany CINECA SCAI–SuperComputing Applications and Innovation Department Rome Branch Italy Helmholtz Institute Erlangen-Nürnberg for Renewable Energy Erlangen Germany Department of Chemical and Biological Engineering and Department of Physics Friedrich-Alexander-Universität Erlangen Germany

Fluid dynamics simulations with the lattice Boltzmann method (LBM) are very memory intensive. Alongside reduction in memory footprint, significant performance benefits can be achieved by using FP32 (single) precision compared to FP64 (double) precision, especially on GPUs. Here we evaluate the possibility to use even FP16 and posit16 (half) precision for storing fluid populations, while still carrying arithmetic operations in FP32. For this, we first show that the commonly occurring number range in the LBM is a lot smaller than the FP16 number range. Based on this observation, we develop customized 16-bit formats—based on a modified IEEE-754 and on a modified posit standard—that are specifically tailored to the needs of the LBM. We then carry out an in-depth characterization of LBM accuracy for six different test systems with increasing complexity: Poiseuille flow, Taylor-Green vortices, Karman vortex streets, lid-driven cavity, a microcapsule in shear flow (utilizing the immersed-boundary method), and, finally, the impact of a raindrop (based on a volume-of-fluid approach). We find that the difference in accuracy between FP64 and FP32 is negligible in almost all cases, and that for a large number of cases even 16-bit is sufficient. Finally, we provide a detailed performance analysis of all precision levels on a large number of hardware microarchitectures and show that significant speedup is achieved with mixed FP32/16-bit.

关键词： Biological fluid dynamics Drop & bubble phenomena Fluid-particle interactions Interactions in fluids Interfacial flows microfluidics Physics of computation Shear flows Vortex flows Classical fluids Complex fluids Lattice models in statistical physics Numerical techniques

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Determination of filtration and consolidation properties of protein crystal suspensions using analytical photocentrifuges with low volume samples

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CHEMICAL engineering SCIENCE 2019年 196卷 72-81页

作者： Radel, B. Funck, M. Nguyen, T. H. Nirschl, H. Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Strasse am Forum 8 76131 Karlsruhe Germany

Proteins and in particular pharmaceutical proteins like monoclonal antibodies are expensive products. Protein crystallization is an interesting alternative process step to the common purification and formulation of such proteins. The solid-liquid separation of proteins however, is a challenging task because the proteins are sensitive to mechanical stress, which could lead to crystal breakage and often are only available in small amounts for research and development. In this study a newly developed filtration cell for the LUMiSizer (R) centrifuge is used to analyze the filtration behavior with low volume samples. Isometric and needle shaped lysozyme crystals serve as model protein crystals. The needle shaped crystals showed about twice as high compressibility and much higher cake resistance than the isometric lysozyme crystals. After the filtration at maximum pressure in the centrifuge the mean particle diameter decreased compared to the unstressed median diameter. With the filtration cell the cake height and filter cake compression can be monitored in situ and the filter cake resistance and solids volume fraction can be calculated with one experiment using 200-300 ( )mu l sample. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Centrifugal filtration Cake filtration Protein crystals

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The role of fluid friction in streamer formation and biofilm growth

arXiv

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arXiv 2024年

作者： Wittig, Cornelius Wagner, Michael Vallon, Romain Crouzier, Thomas van der Wijngaart, Wouter Horn, Harald Bagheri, Shervin FLOW Center Dept. of Engineering Mechanics KTH StockholmSE-100 44 Sweden Eggenstein-Leopoldshafen Germany DTU Dept. of Health Technology Kongens LyngbyDK-2800 Denmark Division of Micro and Nanosystems Dept. of Intelligent Systems KTH StockholmSE-100 44 Sweden Karlsruhe Institute of Technology Engler-Bunte-Institut Karlsruhe Germany

Bacillus subtilis biofilms were grown in laminar channel flow at wall shear stress spanning one order of magnitude (τw = 0.068 Pa to τw = 0.67 Pa). We monitor, noninvasively, the evolution of the three-dimensional distribution of biofilm over seven days using optical coherence tomography (OCT). The obtained biofilms consist of many microcolonies where the characteristic colony has a base structure in the form of a leaning pillar and a streamer in the form of a thin filament that originates near the tip of the pillar. While the shape, size and distribution of these microcolonies depend on the imposed shear stress, the same structural features appear consistently for all shear stress values. The formation of streamers seems to occur after the development of a base structure, suggesting that the latter induces a curved secondary flow that triggers the formation of the streamers. Moreover, we observe that the biofilm volume grows approximately linearly over seven days for all the shear stress values, with a growth rate that is inversely proportional to the wall shear stress. We develop a simple model of friction-limited growth, which agrees with the experimental observations. The model provides physical insight into growth mechanisms and can be used to develop accurate continuum models of bacterial biofilm growth. © 2024, CC BY.

关键词： Biofilms

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Coupling of multiscale lattice Boltzmann discrete-element method for reactive particle fluid flows

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Physical Review E 2021年第3期103卷 033306-033306页

作者： Marie-Luise Maier Ravi A. Patel Nikolaos I. Prasianakis Sergey V. Churakov Hermann Nirschl Mathias J. Krause Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology (KIT) Karlsruhe Germany Lattice Boltzmann Research Group KIT Karlsruhe Germany Institute for Concrete Structures and Building Materials and materials testing laboratory (IMB/MPA) Karlsruhe Institute of Technology (KIT) Karlsruhe Germany formerly at Laboratory for Waste Management Paul Scherrer Institute Villigen Switzerland Laboratory for Waste Management Paul Scherrer Institute Villigen Switzerland Institute of Geological Sciences University of Berne Switzerland Institute for Applied and Numerical Mathematics KIT Karlsruhe Germany

Reactive particulate systems are of prime importance in varieties of practical applications in process engineering. As an example this study considers extraction of phosphorous from waste water by calcium silicate hydrate particles in the P-RoC process. For such systems modeling has a large potential to help to optimize process conditions, e.g., particle-size distributions or volume flows. The goal of this study is to present a new generic modeling framework to capture relevant aspects of reactive particle fluid flows using combined lattice Boltzmann method and discrete-element method. The model developed is Euler-Lagrange scheme which consist of three-components viz., a fluid phase, a dissolved reactive substance, and suspended particles. The fluid flow and reactive mass transport are described in a continuum framework using volume-averaged Navier-Stokes and volume-averaged advection-diffusion-reaction equations, respectively, and solved using lattice Boltzmann methods. The volume-averaging procedure ensures correctness in coupling between fluid flow, reactive mass transport, and particle motion. The developed model is validated through series of well-defined benchmarks. The benchmarks include the validation of the model with experimental data for the settling of a single particle in a cavity filled with water. The benchmark to validate the multi-scale reactive transport involves comparing the results with a resolved numerical simulation. These benchmarks also prove that the proposed model is grid convergent which has previously not been established for such coupled models. Finally, we demonstrate the applicability of our model by simulating a suspension of multiple particles in fluid with a dissolved reactive substance. Comparison of this coupled model is made with a one-way coupled simulation where the influence of particles on the fluid flow and the reactive solution transport is not considered. This elucidates the need for the two-way coupled model.

关键词： Fluid-particle interactions Particle-laden flows Reacting flows

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engineering Electronic Density and Coordination Environment of Mn–Nx Sites via Zn Cooperation for Quasi-Solid-State Zinc-Air Batteries

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Renewables 2023年第3期1卷 362-372页

作者： Daijie Deng Huixin Ma Suqin Wu Huan Wang Junchao Qian Jianchun Wu Huaming Li Cheng Yan Henan Li Li Xu Institute for Energy Research School of Chemistry and Chemical EngineeringSchool of Materials Science and EngineeringJiangsu UniversityZhenjiang 212013Jiangsu Jiangsu Key Laboratory for Environment Functional Materials Suzhou University of Science and TechnologySuzhou 215009Jiangsu Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province Nanjing 210023 School of Mechanical Medical and Process EngineeringQueensland University of TechnologyBrisbaneQueensland 4001

Due to the poor Fenton reactivity,single-atom Mn-based materials are generally identified as one of the most promising active catalysts for oxygen reduction reaction(ORR).Regulating the electronic density and coordination environment of atomically dispersed Mn centers is an effective strategy to enhance ORR activity of Mn-based *** introducing Zn sites,atomically dispersed Mn centers with multitudes of coordination(including Zn/Mn–Nx and Mn–Nx moieties)can be constructed to form Mn-based ORR catalyst(Zn/Mn-NC)with dual-atom *** Mn–Nx sites,the Zn atoms can effectively modulate the electronic structure and coordination state of Mn centers in Zn/Mn-NC through d–d orbital *** electronic interaction between Zn and Mn sites improves ORR activity,thereby optimizing the oxygen adsorption energy of Mn sites in Zn/Mn-NC and reducing the overall energy ***/Mn-NC displays higher ORR half-wave potential than Pt/C(0.89 V vs 0.86 V).The quasi-solid-state zinc-air battery(ZAB)with Zn/Mn-NC as the cathode displayed excellent rechargeability,recyclability,and mechanical *** strategy presented regulates the electronic density and coordination environment of singleatom Mn-based ORR catalysts in quasi-solid-state ZABs.

关键词： quasi-solid-state zinc-air batteries oxygen reduction reaction dual-atom sites Mn-Nx Zn/Mn-Nx

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Effect of elongational flow behavior on ligament disintegration and drop formation by means of a high-speed rotary bell atomizer 14

Effect of elongational flow behavior on ligament disintegrat...

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14th International Conference on Liquid Atomization and Spray Systems, ICLASS 2018

作者： Oswald, Walter Gödeke, Lutz Ehrhard, Peter Willenbacher, Norbert Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Germany Department of Biochemical and Chemical Engineering Fluid Mechanics Technische Universität Dortmund Germany

High-speed rotary bell atomization is widely used in the automotive industry. It is characterized by high coating quality at short process times. In this application, ligaments are formed at the bell edge and disintegrate into droplets. Since resulting coating layer quality depends on atomization, it is essential to investigate this process. Numerous studies have dealt with the influence of material properties and application parameters on droplet size for Newtonian fluids. However, effects of elongational flow resistance and viscoelastic fluid properties on atomization have not been investigated in detail. In this study a model system is used, allowing for a variation of elongational flow behavior at essentially constant shear flow properties. The latter were determined using rotational and capillary rheometry. Elongational flow resistance was characterized using Capillary Breakup Elongational Rheometry (CaBER). Information about ligament disintegration was extracted from high-speed video recordings at the bell edge. Droplet size distribution was determined using Phase-Doppler-Anemometry (PDA). We show that increasing elongational flow resistance stabilizes ligaments towards disintegration but does not influence droplet size. Decreasing rotational speed leads to an increase of ligament length and droplet size, whereas volume flow rate hardly influences atomization results. © 2018 Solar Turbines Incorporated.

关键词： Coatings

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Erratum: Challenges of Predicting Temperature Dependent Capacity Loss Using the Example of NMC-LMO Lithium-Ion Battery Cells [J. Electrochem. Soc., 171, 040538 (2024)]

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Journal of The Electrochemical Society 2024年第12期171卷 129001-129001页

作者： L. Cloos J. Langer M. Schiffler A. Weber Th. Wetzel Institute of Thermal Process Engineering (TVT) Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany Institute for Applied Materials - Electrochemical Technologies (IAM-ET) Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany

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Challenges and Prospects of Automated Disassembly of Fuel Cells for a Circular Economy

SSRN

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SSRN 2023年

作者： Al Assadi, Anwar Goes, Dominik Baazouzi, Sabri Staudacher, Malena Kraus, Werner Malczyk, Piotr Peuker, Urs Fleischer, Jürgen Huber, Marco F. Birke, Kai Peter Nägele, Frank University of Stuttgart Germany Fraunhofer Institute for Manufacturing Engineering and Automation IPA Nobelstraße 12 Stuttgart70569 Germany University of Stuttgart Institute of Industrial Manufacturing and Management IFF Allmandring 35 Stuttgart70569 Germany wbk Institute of Production Science KIT Karlsruhe Institute of Technology Kaiserstraße 12 Karlsruhe76131 Germany Institute of Mechanical Process Engineering and Mineral Processing Technical University Bergakademie Freiberg Agricolastraße 1 Freiberg09599 Germany Institute of Ceramics Refractories and Composite Materials Technical University Bergakademie Freiberg Agricolastraße 17 Freiberg09599 Germany

The hydrogen economy is driven by the growing share of renewable energy and electrification of the transportation sector. The essential components of a hydrogen economy are fuel cells and electrolysis systems. The scarcity of the resources to build these components and the negative environmental impact of their mining requires a circular economy. Concerning disassembly, economical, ergonomic, and safety reasons make a higher degree of automation necessary. Our work outlines the challenges and prospects on automated disassembly of fuel cell stacks. This is carried out by summarizing the state-of-the-art approaches in disassembly and conducting manual non-/destructive disassembly experiments of end-of-life fuel cell stacks. Based on that, a chemical and mechanical analysis of the fuel cell components is performed. From this, an automation potential for the disassembly processes is derived and possible disassembly process routes are modeled. Moreover, recommendations are given regarding disassembly system requirements using a morphological box. © 2023, The Authors. All rights reserved.

关键词： Fuel cells

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Modelling the phosphorus dynamics of VPO catalyst during n-butane oxidation: A μ-reactor study

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Chemical engineering Science 2025年 316卷

作者： Anderson, Scott D. Kutscherauer, Martin Wehinger, Gregor D. Mestl, Gerhard Turek, Thomas Institute of Chemical and Electrochemical Process Engineering Clausthal University of Technology Leibnizstraße 17 Clausthal-Zellerfeld38678 Germany Institute of Chemical Process Engineering Karlsruhe Institute of Technology Fritz-Haber-Weg 2 Karlsruhe76131 Germany Clariant AG Waldheimer Strasse 15 Heufeld83052 Germany

Production of maleic anhydride from n-butane is carried out in large fixed-bed reactors, which face a multitude of challenges, amongst them the removal of heat produced by the reaction, alongside a transient increase in activity due to phosphorus loss from the catalyst, causing a shift in selectivities and loss in target product yield. Improved modelling can aid in a better understanding of the involved processes, such that operating policies can be optimized. However, this necessitates the coupling of models for all subprocesses, that are parameterised independently of one another. To date, especially the phosphorus dynamics are not well understood and lack models to describe them. Experiments involving µ-reactor phosphorus dosing under transport limitation-free conditions are reported, investigating the underlying mechanisms of the phosphorus dynamics. Based on this data, an activity model comprising only four parameters is developed. Results indicate that a site-blocking mechanism plays a role in the phosphorus dynamics. © 2025 The Authors

关键词： n -butane Maleic anhydride Modelling Phosphorus dynamics Selective oxidation

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pH-Responsive silk protein/ZIF-8@bacitracin composite coating on strontium-doped nanorod surface for combating implant-associated infections

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International Journal of Biological Macromolecules 2025年 315卷 144661页

作者： Tian, Zitong Guan, Jiaxin Su, Hui Guan, Lingdi Yang, Hao Xia, Chengcheng Han, Pengde Lin, He Zhang, Xiaojun Lan, Jinping Qiao, Haixia Huang, Yong Sang, Shengbo College of Lab Medicine Life Science Research Centre Key Laboratory of Biomedical Materials of Zhangjiakou Hebei North University Zhangjiakou075000 China School of Medicine Northwest University Xi'an710069 China Key Laboratory for Green Chemical Process of Ministry of Education Wuhan Institute of Technology Wuhan430205 China School of Materials Science and Engineering Yancheng Institute of Technology Yancheng224051 China School of Chemistry and Materials Science Ludong University Yantai264025 China Shanxi Key Laboratory of Micro Nano Sensors & Artificial Intelligence Taiyuan University of Technology Taiyuan030600 China

Titanium-based bone repair materials often face bacterial infections, resulting in inflammation and impaired osseointegration. To address this issue, we developed a multifunctional coating by encapsulating bacitracin within a metal-organic framework (ZIF-8@B) and incorporating it into a strontium-doped titanium dioxide nanorod (STN) structure using silk protein (SF). This coating, termed STN-SF/ZIF-8@B, was applied to titanium surfaces. It demonstrated outstanding hydrophilicity, corrosion resistance, hemocompatibility, and biosafety. The synergistic effects of bacitracin and Zn2+ achieved over 80 % inhibition against both E. coli and S. aureus. Additionally, STN-SF/ZIF-8@B effectively reprogrammed inflammatory macrophages into an anti-inflammatory M2 phenotype. The combined actions of Sr2+ and Zn2+ significantly enhanced the migration, lumen formation, and expression of angiogenic growth factors in HUVEC. Moreover, STN-SF/ZIF-8@B upregulated the expression of genes and proteins related to osteogenesis, promoting the osteogenic differentiation of MC3T3-E1 cells. In vivo experiments utilizing a rat bone defect model revealed that STN-SF/ZIF-8@B exhibited superior anti-inflammatory, antibacterial, pro-angiogenic, and osteogenic properties. This study provided a promising approach for the development of advanced biomaterials that simultaneously address infection control, immune modulation, angiogenesis, and bone regeneration, offering significant potential for improving the outcomes of bone defect repair in clinical applications. © 2025 Elsevier B.V.

关键词： Nanorods

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