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Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computationalfluid dynamic and reaction kinetic modeling

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1149-1163 doi: 10.1007/s11705-021-2096-0

摘要： The production of solar fuels via the photoreduction of carbon dioxide to methane by titanium oxide is a promising process to control greenhouse gas emissions and provide alternative renewable fuels. Although several reaction mechanisms have been proposed, the detailed steps are still ambiguous, and the limiting factors are not well defined. To improve our understanding of the mechanisms of carbon dioxide photoreduction, a multiphysics model was developed using COMSOL. The novelty of this work is the computational fluid dynamic model combined with the novel carbon dioxide photoreduction intrinsic reaction kinetic model, which was built based on three-steps, namely gas adsorption, surface reactions and desorption, while the ultraviolet light intensity distribution was simulated by the Gaussian distribution model and Beer-Lambert model. The carbon dioxide photoreduction process conducted in a laboratory-scale reactor under different carbon dioxide and water moisture partial pressures was then modeled based on the intrinsic kinetic model. It was found that the simulation results for methane, carbon monoxide and hydrogen yield match the experiments in the concentration range of 10−4 mol·m–3 at the low carbon dioxide and water moisture partial pressure. Finally, the factors of adsorption site concentration, adsorption equilibrium constant, ultraviolet light intensity and temperature were evaluated.

关键词： carbon dioxide photoreduction     computational fluid dynamic simulation     kinetic model     Langmuir adsorption    

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Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 586-598 doi: 10.1007/s11709-020-0573-z

摘要： This paper presents a review of fracture modeling of concrete. The complex material, such as concrete, has been widely used in construction industries and become trending issue in the last decades. Based on comprehensive literature review, there are two main approaches considered to-date of concrete fracture modeling, such as macroscopic and micromechanical models. The purpose of this review is to provide insight comparison from different techniques in modeling of fracture in concrete which are available. In the first section, an overview of fracture modeling in general is highlighted. Two different approaches both of macroscopic and micromechanical models will be reviewed. As heterogeneity of concrete material is major concern in micromechanical-based concrete modeling, one section will discuss this approach. Finally, the summary from all of reviewed techniques will be pointed out before the future perspective is given.

关键词： concrete fracture     macroscopic     micromechanical     heterogeneity    

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Revisiting digital twins: Origins, fundamentals, and practices

《工程管理前沿（英文）》   页码 668-676 doi: 10.1007/s42524-022-0216-2

摘要： The digital twins (DT) has quickly become a hot topic since it was proposed. It appears in all kinds of commercial propaganda and is widely quoted by academic circles. However, the term DT has misstatements and is misused in business and academics. This study revisits DT and defines it to be a more advanced system/product/service modeling and simulation environment that combines most modern information communication technologies (ICTs) and engineering mechanism digitization and characterized by system/product/service life cycle management, physically geometric visualization, real-time sensing and measurement of system operating conditions, predictability of system performance/safety/lifespan, and complete engineering mechanisms-based simulations. The idea of DT originates from modeling and simulation practices of engineering informatization, including virtual manufacturing (VM), model predictive control, and building information modeling (BIM). On the basis of the two-element VM model, we propose a three-element model to represent DT. DT does not have its unique technical characteristics. The existing practices of DT are extensions of the engineering informatization embracing modern ICTs. These insights clarify the origin of DT and its technical essentials.

关键词： virtual manufacturing     digital twins     modeling and simulation     digitization     computational engineering    

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An investigation of ballistic response of reinforced and sandwich concrete panels using computational

Mohammad HANIFEHZADEH, Bora GENCTURK

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1120-1137 doi: 10.1007/s11709-019-0540-8

摘要： Structural performance of nuclear containment structures and power plant facilities is of critical importance for public safety. The performance of concrete in a high-speed hard projectile impact is a complex problem due to a combination of multiple failure modes including brittle tensile fracture, crushing, and spalling. In this study, reinforced concrete (RC) and steel-concrete-steel sandwich (SCSS) panels are investigated under high-speed hard projectile inpact. Two modeling techniques, smoothed particle hydrodynamics (SPH) and conventional finite element (FE) analysis with element erosion are used. Penetration depth and global deformation are compared between doubly RC and SCSS panels in order to identify the advantages of the presence of steel plates over the reinforcement layers. A parametric analysis of the front and rear plate thicknesses of the SCSS configuration showed that the SCSS panel with a thick front plate has the best performance in controlling the hard projectile. While a thick rear plate is effective in the case of a large and soft projectile as the plate reduces the rear deformation. The effects of the impact angle and impact velocity are also considered. It was observed that the impact angle for the flat nose missile is critical and the front steel plate is effective in minimizing penetration depth.

关键词： concrete panels     projectile impact     finite element modeling     smoothed particle hydrodynamics     strain rate effect    

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The computational fluid dynamic modeling of downwash flow field for a six-rotor UAV

Yongjun ZHENG, Shenghui YANG, Xingxing LIU, Jie WANG, Tomas NORTON, Jian CHEN, Yu TAN

《农业科学与工程前沿（英文）》 2018年 第5卷 第2期   页码 159-167 doi: 10.15302/J-FASE-2018216

摘要： The downwash flow field of the multi-rotor unmanned aerial vehicle (UAV), formed by propellers during operation, has a significant influence on the deposition, drift and distribution of droplets as well as the spray width of the UAV for plant protection. To study the general characteristics of the distribution of the downwash airflow and simulate the static wind field of multi-rotor UAVs in hovering state, a 3D full-size physical model of JF01-10 six-rotor plant protection UAV was constructed using SolidWorks. The entire flow field surrounding the UAV and the rotation flow fields around the six rotors were established in UG software. The physical model and flow fields were meshed using unstructured tetrahedral elements in ANSYS software. Finally, the downwash flow field of UAV was simulated. With an increased hovering height, the ground effect was reduced and the minimum current velocity increased initially and then decreased. In addition, the spatial proportion of the turbulence occupied decreased. Furthermore, the appropriate operational hovering height for the JF01-10 is considered to be 3 m. These results can be applied to six-rotor plant protection UAVs employed in pesticide spraying and spray width detection.

关键词： CFD simulation     downwash flow field     numerical analysis     plant protection     six-rotor UAV    

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Stormwater treatment: examples of computational fluid dynamics modeling

Gaoxiang YING, John SANSALONE, Srikanth PATHAPATI, Giuseppina GAROFALO, Marco MAGLIONICO, Andrea BOLOGNESI, Alessandro ARTINA

《环境科学与工程前沿（英文）》 2012年 第6卷 第5期   页码 638-648 doi: 10.1007/s11783-012-0442-7

摘要： Control of rainfall-runoff particulate matter (PM) and PM-bound chemical loads is challenging; in part due to the wide gradation of PM complex geometries of many unit operations and variable flow rates. Such challenges and the expense associated with resolving such challenges have led to the relatively common examination of a spectrum of unit operations and processes. This study applies the principles of computational fluid dynamics (CFD) to predict the particle and pollutant clarification behavior of these systems subject to dilute multiphase flows, typical of rainfall-runoff, within computationally reasonable limits, to a scientifically acceptable degree of accuracy. The Navier-Stokes (NS) system of nonlinear partial differential equations for multi-phase hydrodynamics and separation of entrained particles are solved numerically over the unit operation control volume with the boundary and initial conditions defined and then solved numerically until the desired convergence criteria are met. Flow rates examined are scaled based on sizing of common unit operations such as hydrodynamic separators (HS), wet basins, or filters, and are examined from 1 to 100 percent of the system maximum hydraulic operating flow rate. A standard turbulence model is used to resolve flow, and a discrete phase model (DPM) is utilized to examine the particle clarification response. CFD results closely follow physical model results across the entire range of flow rates. Post-processing the CFD predictions provides an in-depth insight into the mechanistic behavior of unit operations by means of three dimensional (3-D) hydraulic profiles and particle trajectories. Results demonstrate the role of scour in the rapid degradation of unit operations that are not maintained. Comparisons are provided between measured and CFD modeled results and a mass balance error is identified. CFD is arguably the most powerful tool available for our profession since continuous simulation modeling.

关键词： stormwater     unit operations and processes (UOPs)     hydrodynamic separation     filtration     adsorption     computational fluid dynamics (CFD)     turbulence modeling     discrete phase model     particle separation     detention/retention basins     clarification    

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Computational modeling of fracture in capsule-based self-healing concrete: A 3D study

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1337-1346 doi: 10.1007/s11709-021-0781-1

摘要： We present a three-dimensional (3D) numerical model to investigate complex fracture behavior using cohesive elements. An efficient packing algorithm is employed to create the mesoscale model of heterogeneous capsule-based self-healing concrete. Spherical aggregates are used and directly generated from specified size distributions with different volume fractions. Spherical capsules are also used and created based on a particular diameter, and wall thickness. Bilinear traction-separation laws of cohesive elements along the boundaries of the mortar matrix, aggregates, capsules, and their interfaces are pre-inserted to simulate crack initiation and propagation. These pre-inserted cohesive elements are also applied into the initial meshes of solid elements to account for fracture in the mortar matrix. Different realizations are carried out and statistically analyzed. The proposed model provides an effective tool for predicting the complex fracture response of capsule-based self-healing concrete at the meso-scale.

关键词： 3D fracture     self-healing concrete     spherical     cohesive elements     heterogeneous    

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A multiscale material model for heterogeneous liquid droplets in solid soft composites

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1292-1299 doi: 10.1007/s11709-021-0771-3

摘要： Liquid droplets in solid soft composites have been attracting increasing attention in biological applications. In contrary with conventional composites, which are made of solid elastic inclusions, available material models for composites including liquid droplets are for highly idealized configurations and do not include all material real parameters. They are also all deterministic and do not address the uncertainties arising from droplet radius, volume fraction, dispersion and agglomeration. This research revisits the available models for liquid droplets in solid soft composites and presents a multiscale computational material model to determine their elastic moduli, considering nearly all relevant uncertainties and heterogeneities at different length scales. The effects of surface tension at droplets interface, their volume fraction, size, size polydispersity and agglomeration on elastic modulus, are considered. Different micromechanical material models are incorporated into the presented computational framework. The results clearly indicate both softening and stiffening effects of liquid droplets and show that the model can precisely predict the effective properties of liquid droplets in solid soft composites.

关键词： liquid in solid     soft composite     computational modeling     multiscale model     heterogeneity    

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Reduced kinetic mechanism of -heptane oxidation in modeling polycyclic aromatic hydrocarbon formation

ZHONG Beijing, XI Jun

《能源前沿（英文）》 2008年 第2卷 第3期   页码 326-332 doi: 10.1007/s11708-008-0047-9

摘要： A reduced mechanism, which could couple with the multidimensional computational fluid dynamics code for quantitative description of a reacting flow, was developed for chemical kinetic modeling of polycyclic aromatic hydrocarbon formation in an opposed-flow diffusion flame. The complete kinetic mechanism, which comprises 572 reactions and 108 species, was reduced to a simplified mechanism that includes only 83 reactions and 56 species through sensitivity analysis. The results computed via this reduced mechanism are nearly indistinguishable from those via the detailed mechanism, which demonstrate that the model based on this reduced mechanism can properly describe -heptane oxidation chemistry and quantitatively predict polycyclic aromatic hydrocarbon (such as benzene, naphthalene, phenanthrene and pyrene) formation in opposed-flow diffusion flames.

关键词： phenanthrene     multidimensional computational     sensitivity analysis     polycyclic     mechanism    

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Structural optimization of filament wound composite pipes

Roham RAFIEE; Reza SHAHZADI; Hossein SPERESP

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1056-1069 doi: 10.1007/s11709-022-0868-3

摘要： An optimization procedure is developed for obtaining optimal structural design of filament wound composite pipes with minimum cost utilized in pressurized water and waste-water pipelines. First, the short-term and long-term design constraints dictated by international standards are identified. Then, proper computational tools are developed for predicting the structural properties of the composite pipes based on the design architecture of layers. The developed computational tools are validated by relying on experimental analysis. Then, an integrated design-optimization process is developed to minimize the price as the main objective, taking into account design requirements and manufacturing limitations as the constraints and treating lay-up sequence, fiber volume fraction, winding angle, and the number of total layers as design variables. The developed method is implemented in various case studies, and the results are presented and discussed.

关键词： composite pipes     optimization     experimental validation     computational modeling     filament winding    

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Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1071-1088 doi: 10.1007/s11709-022-0879-0

摘要： For open car park structures, adopting a performance-based structural fire design is often justified and allowed because the fire does not reach flashover. However, this design approach requires an accurate assessment of temperatures in structural members exposed to car fires. This paper describes a numerical study on the thermal exposure on steel framing members in open car park fires. Steel temperatures are computed by the coupling of computational fluid dynamics and finite element modeling, and by analytical models from the Eurocodes. In addition, the influence of galvanization on the steel temperature evolution is assessed. Results show that temperatures in unprotected beams and columns are influenced by the section geometry, car fire scenario, modeling approach, and use of galvanization. Galvanization slightly delays and reduces peak temperature. Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method) coupled models predict lower temperatures than the Hasemi model, because the latter conservatively assumes that the fire flame continuously touches the ceiling. Further, the Hasemi model cannot account for the effect of reduced emissivity from galvanization on the absorbed heat flux. Detailed temperature distributions obtained in the steel members can be used to complete efficient structural fire designs based on the member sections, structure layout, and use of galvanization.

关键词： open car park     localized fire     steel frame     numerical modeling     computational fluid dynamics    

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Macro-architectured cellular materials: Properties, characteristic modes, and prediction methods

Zheng-Dong MA

《机械工程前沿（英文）》 2018年 第13卷 第3期   页码 442-459 doi: 10.1007/s11465-018-0488-8

摘要：

Macro-architectured cellular (MAC) material is defined as a class of engineered materials having configurable cells of relatively large (i.e., visible) size that can be architecturally designed to achieve various desired material properties. Two types of novel MAC materials, negative Poisson’s ratio material and biomimetic tendon reinforced material, were introduced in this study. To estimate the effective material properties for structural analyses and to optimally design such materials, a set of suitable homogenization methods was developed that provided an effective means for the multiscale modeling of MAC materials. First, a strain-based homogenization method was developed using an approach that separated the strain field into a homogenized strain field and a strain variation field in the local cellular domain superposed on the homogenized strain field. The principle of virtual displacements for the relationship between the strain variation field and the homogenized strain field was then used to condense the strain variation field onto the homogenized strain field. The new method was then extended to a stress-based homogenization process based on the principle of virtual forces and further applied to address the discrete systems represented by the beam or frame structures of the aforementioned MAC materials. The characteristic modes and the stress recovery process used to predict the stress distribution inside the cellular domain and thus determine the material strengths and failures at the local level are also discussed.

关键词： architectured material     cellular materials     multi-scale modeling     homogenization method     effective material properties     computational method    

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Research Trends in Fischer--Tropsch Catalysis for Coal to Liquids Technology

Emiel J. M. Hensen,Peng Wang,Wayne Xu

《工程管理前沿（英文）》 2016年 第3卷 第4期   页码 321-330 doi: 10.15302/J-FEM-2016051

摘要： Fischer–Tropsch Synthesis (FTS) constitutes catalytic technology that converts synthesis gas to synthetic liquid fuels and chemicals. While synthesis gas can be obtained from any carbonaceous feedstock, current industrial FTS operations are almost exclusively based on natural gas. Due to the energy structure of China where cheap coal is abundant, coal to liquids (CTL) technology involving coal gasification, FTS and syncrude upgrading is increasingly being considered as a viable option to convert coal to clean transportation fuels. In this brief paper, we review some pertinent issues about Fe- and Co-based FTS catalysts. Fe is better suited to convert synthesis gas derived from coal gasification into fuels. The authors limit themselves to noting some important trends in the research on Fe-based catalysts. They focus on the preparation of phase-pure carbides and innovative cheap synthesis methods for obtaining active and stable catalysts. These approaches should be augmented by (1) computational investigations that are increasingly able to predict not only mechanism, reaction rates and selectivity but also optimum catalyst composition, as well as (2) characterization of the catalytic materials under conditions close to the operation in real reactors.

关键词： Fischer–Tropsch     FTS     CTL     Fe catalyst     iron carbide     computational modeling    

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Simulation of abrasive flow machining process for 2D and 3D mixture models

Rupalika DASH,Kalipada MAITY

《机械工程前沿（英文）》 2015年 第10卷 第4期   页码 424-432 doi: 10.1007/s11465-015-0366-6

摘要：

Improvement of surface finish and material removal has been quite a challenge in a finishing operation such as abrasive flow machining (AFM). Factors that affect the surface finish and material removal are media viscosity, extrusion pressure, piston velocity, and particle size in abrasive flow machining process. Performing experiments for all the parameters and accurately obtaining an optimized parameter in a short time are difficult to accomplish because the operation requires a precise finish. Computational fluid dynamics (CFD) simulation was employed to accurately determine optimum parameters. In the current work, a 2D model was designed, and the flow analysis, force calculation, and material removal prediction were performed and compared with the available experimental data. Another 3D model for a swaging die finishing using AFM was simulated at different viscosities of the media to study the effects on the controlling parameters. A CFD simulation was performed by using commercially available ANSYS FLUENT. Two phases were considered for the flow analysis, and multiphase mixture model was taken into account. The fluid was considered to be a Newtonian fluid and the flow laminar with no wall slip.

关键词： abrasive flow machining (AFM)     computational fluid dynamics (CFD) modeling     mixture model    

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Challenges of high dam construction to computational mechanics

ZHANG Chuhan

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 12-33 doi: 10.1007/s11709-007-0002-6

摘要： The current situations and growing prospects of China s hydro-power development and high dam construction are reviewed, giving emphasis to key issues for safety evaluation of large dams and hydro-power plants, especially those associated with application of state-of-the-art computational mechanics. These include but are not limited to: stress and stability analysis of dam foundations under external loads; earthquake behavior of dam-foundation-reservoir systems, mechanical properties of mass concrete for dams, high velocity flow and energy dissipation for high dams, scientific and technical problems of hydro-power plants and underground structures, and newly developed types of dam-Roll Com pacted Concrete (RCC) dams and Concrete Face Rock-fill (CFR) dams. Some examples demonstrating successful utilizations of computational mechanics in high dam engineering are given, including seismic nonlinear analysis for arch dam foundations, nonlinear fracture analysis of arch dams under reservoir loads, and failure analysis of arch dam-foundations. To make more use of the computational mechanics in high dam engineering, it is pointed out that much research including different computational methods, numerical models and solution schemes, and verifications through experimental tests and filed measurements is necessary in the future.

关键词： reservoir     engineering     hydro-power development     state-of-the-art computational     earthquake    

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标题 作者 时间 类型 操作

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computationalfluid dynamic and reaction kinetic modeling

期刊论文

Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

期刊论文

Revisiting digital twins: Origins, fundamentals, and practices

期刊论文

An investigation of ballistic response of reinforced and sandwich concrete panels using computational

Mohammad HANIFEHZADEH, Bora GENCTURK

期刊论文

The computational fluid dynamic modeling of downwash flow field for a six-rotor UAV

Yongjun ZHENG, Shenghui YANG, Xingxing LIU, Jie WANG, Tomas NORTON, Jian CHEN, Yu TAN

期刊论文

Stormwater treatment: examples of computational fluid dynamics modeling

Gaoxiang YING, John SANSALONE, Srikanth PATHAPATI, Giuseppina GAROFALO, Marco MAGLIONICO, Andrea BOLOGNESI, Alessandro ARTINA

期刊论文

Computational modeling of fracture in capsule-based self-healing concrete: A 3D study

期刊论文

A multiscale material model for heterogeneous liquid droplets in solid soft composites

期刊论文

Reduced kinetic mechanism of -heptane oxidation in modeling polycyclic aromatic hydrocarbon formation

ZHONG Beijing, XI Jun

期刊论文

Structural optimization of filament wound composite pipes

Roham RAFIEE; Reza SHAHZADI; Hossein SPERESP

期刊论文

Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

期刊论文

Macro-architectured cellular materials: Properties, characteristic modes, and prediction methods

Zheng-Dong MA

期刊论文

Research Trends in Fischer--Tropsch Catalysis for Coal to Liquids Technology

Emiel J. M. Hensen,Peng Wang,Wayne Xu

期刊论文

Simulation of abrasive flow machining process for 2D and 3D mixture models

Rupalika DASH,Kalipada MAITY

期刊论文

Challenges of high dam construction to computational mechanics

ZHANG Chuhan

期刊论文