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Extended two-fluid model applied to analysis of bubbly flow in multiphase rotodynamic pump impeller

Zhiyi YU, Guoyu WANG, Shuliang CAO

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 53-59 doi: 10.1007/s11465-009-0006-0

摘要: This paper presents an extended two-fluid model based on the Navier-Stokes equations and the standard turbulence model, to simulate the three-dimensional air-water bubbly flow in turbo machinery. In the governing equations, the drag force and added mass force are added and the additional source terms arising from fluctuations of gas volume fraction are considered. The discrete equations are solved using a developed two-phase semi-implicit method for pressure-linked equations, consistent (SIMPLEC) algorithm in body-fitted coordinates with a staggered grid system. Simulation is then carried out for the pure liquid flow and air-water two-phase flow with the inlet gas volume fraction being 15% in a multiphase rotodynamic pump impeller and the pump head performance is predicted. Comparison with experimental results shows the reliability and commonality of the numerical model.

关键词: two-fluid model     multiphase rotodynamic pump     SIMPLEC algorithm     numerical simulation    

Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 312-320 doi: 10.1007/s11465-017-0433-2

摘要:

This study examines the development of the fluid and control technology of hydraulic wind turbines. The current state of hydraulic wind turbines as a new technology is described, and its basic fluid model and typical control method are expounded by comparing various study results. Finally, the advantages of hydraulic wind turbines are enumerated. Hydraulic wind turbines are expected to become the main development direction of wind turbines.

关键词: wind turbine     hydraulic system     fluid model     control technology    

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid

《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    

Coupled solid-fluid FE-analysis of an embankment dam

Michael PERTL, Matthias HOFMANN, Guenter HOFSTETTER

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 53-62 doi: 10.1007/s11709-010-0084-4

摘要: A coupled solid-fluid FE-model for partially saturated soils, characterized by modeling the soil as a three-phase material consisting of a deformable soil skeleton and the fluid phases water and air, is reviewed briefly. As a constitutive model for the soil skeleton, the well-known Barcelona Basic model (BBM) is employed, which is formulated in terms of net stress and matric suction. For the BBM, a computationally efficient return mapping algorithm is proposed, which only requires the solution of a scalar nonlinear equation at the integration point level. The coupled FE-model is applied to the coupled transient numerical simulation of the water flow and the deformations and stresses in an embankment dam.

关键词: multi-phase model     unsaturated soil model     Barcelona Basic model (BBM)     return mapping algorithm     embankment dam    

Numerical simulation of fluid dynamics in the stirred tank by the SSG Reynolds Stress Model

Nana QI, Hui WANG, Kai ZHANG, Hu ZHANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 506-514 doi: 10.1007/s11705-010-0508-7

摘要: The Speziale, Sarkar and Gatski Reynolds Stress Model (SSG RSM) is utilized to simulate the fluid dynamics in a full baffled stirred tank with a Rushton turbine impeller. Four levels of grid resolutions are chosen to determine an optimised number of grids for further simulations. CFD model data in terms of the flow field, trailing vortex, and the power number are compared with published experimental results. The comparison shows that the global fluid dynamics throughout the stirred tank and the local characteristics of trailing vortices near the blade tips can be captured by the SSG RSM. The predicted mean velocity components in axial, radial and tangential direction are also in good agreement with experiment data. The power number predicted is quite close to the designed value, which demonstrates that this model can accurately calculate the power number in the stirred tank. Therefore, the simulation by using a combination of SSG RSM and MRF impeller rotational model can accurately model turbulent fluid flow in the stirred tank, and it offers an alternative method for design and optimisation of stirred tanks.

关键词: stirred tank     fluid dynamics     numerical simulation     SSG Reynolds Stress Model     MRF    

Thermal fluid-structure interaction and coupled thermal-stress analysis in a cable stayed bridge exposed

Nazim Abdul NARIMAN

《结构与土木工程前沿(英文)》 2018年 第12卷 第4期   页码 609-628 doi: 10.1007/s11709-018-0452-z

摘要: In this paper, thermal fluid structure-interaction (TFSI) and coupled thermal-stress analysis are utilized to identify the effects of transient and steady-state heat-transfer on the vortex induced vibration and fatigue of a segmental bridge deck due to fire incidents. Numerical simulations of TFSI models of the deck are dedicated to calculate the lift and drag forces in addition to determining the lock-in regions once using fluid-structure interaction (FSI) models and another using TFSI models. Vorticity and thermal convection fields of three fire scenarios are simulated and analyzed. Simiu and Scanlan benchmark is used to validate the TFSI models, where a good agreement was manifested between the two results. Extended finite element method (XFEM) is adopted to create 3D models of the cable stayed bridge to simulate the fatigue of the deck considering three fire scenarios. Choi and Shin benchmark is used to validate the damaged models of the deck in which a good coincide was seen between them. The results revealed that TFSI models and coupled thermal-stress models are significant in detecting earlier vortex induced vibration and lock-in regions in addition to predicting damages and fatigue of the deck due to fire incidents.

关键词: fire scenario     transient heat transfer     TFSI model     coupled thermal-stress     XFEM    

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    

Review of the LNG intermediate fluid vaporizer and its heat transfer characteristics

《能源前沿(英文)》 2022年 第16卷 第3期   页码 429-444 doi: 10.1007/s11708-021-0747-y

摘要: The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.

关键词: intermediate fluid vaporizer     design of structure and intermediate fluid     condensation heat transfer    

Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

《环境科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 362-377 doi: 10.1007/s11783-011-0365-8

摘要: In this article computational fluid dynamics (CFD) simulation of aerosol transport and deposition, i.e. the transport and deposition of particles in an aerosol, is reviewed. The review gives a brief account of the basics of aerosol mechanics, followed by a description of the general CFD approach for flow field simulation, turbulence modeling, wall treatments and simulation of particle motion and deposition. Then examples from the literature are presented, including CFD simulation of particle deposition in human respiratory tract and particle deposition in aerosol devices. CFD simulation of particle transport and deposition may provide information that is difficult to obtain through physical experiments, and it may help reduce the number of experiments needed for device design. Due to the difficulty of describing turbulent flow and particle-eddy interaction, turbulent dispersion of particles remains one of the greatest challenges for CFD simulation. However, it is possible to take a balanced approach toward quantitative description of aerosol dispersion using CFD simulation in conjunction with empirical relations.

关键词: computational fluid dynamics (CFD)     aerosol     transport     deposition    

Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 310-315 doi: 10.1007/s11465-009-0039-4

摘要: This paper presents the development and characterization of a magnetorheological (MR) fluid-based variable stiffness and damping isolator. The prototype of the MR fluid isolator is fabricated, and its dynamic behavior is measured under various applied magnetic fields. The parameters of the model under various magnetic fields are identified, and the dynamic performance of the isolator is evaluated in simulation. Experimental results indicate that both the stiffness and damping capability of the developed MR isolator can be controlled by an external magnetic field.

关键词: magnetorheological (MR) fluid     stiffness     damping     mathematical model     dynamic performance     parameter identification    

Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 162-172 doi: 10.1007/s11705-009-0267-5

摘要: Bubble columns are widely used in chemical and biochemical processes due to their excellent mass and heat transfer characteristics and simple construction. However, their fundamental hydrodynamic behaviors, which are essential for reactor scale-up and design, are still not fully understood. To develop design tools for engineering purposes, much research has been carried out in the area of computational fluid dynamics (CFD) modeling and simulation of gas-liquid flows. Due to the importance of the bubble behavior, the bubble size distribution must be considered in the CFD models. The population balance model (PBM) is an effective approach to predict the bubble size distribution, and great efforts have been made in recent years to couple the PBM into CFD simulations. This article gives a selective review of the modeling and simulation of bubble column reactors using CFD coupled with PBM. Bubble breakup and coalescence models due to different mechanisms are discussed. It is shown that the CFD-PBM coupled model with proper bubble breakup and coalescence models and interphase force formulations has the ability of predicting the complex hydrodynamics in different flow regimes and, thus, provides a unified description of both the homogeneous and heterogeneous regimes. Further study is needed to improve the models of bubble coalescence and breakup, turbulence modification in high gas holdup, and interphase forces of bubble swarms.

关键词: bubble column     computational fluid dynamics     bubble breakup and coalescence     population balance model     bubble size distribution    

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

Zhiqiang ZHANG , Aiqun LI , Jianping HE , Jianlei WANG ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 249-254 doi: 10.1007/s11709-009-0038-x

摘要: The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation. Firstly, according to the random vibration theory, the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process, and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained. On the basis of the others’ works, a bi-model dynamic model is proposed. Finally, a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers, and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives. Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code. The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper, and the peak acceleration responses of the upper turret is reduced by 43.4%.

关键词: high-rise structure     wind-induced response     fluid viscous damper     vibration control    

system for thermal convection of viscoelastic fluids in a porous layer using a thermal nonequilibrium model

Qi WEI, Xiaohui ZHANG

《能源前沿(英文)》 2010年 第4卷 第4期   页码 507-516 doi: 10.1007/s11708-010-0017-x

摘要: Thermal convection of viscoelastic fluids saturating a horizontal porous layer heated from below is analyzed using a thermal nonequilibrium model to take account of the interphase heat transfer between the fluid and the solid. The viscoelastic character of the flow is considered by a modified Darcy’s law. An autonomous system with five differential equations is deduced by applying the truncated Galerkin expansion to the momentum and heat transfer equations. The effects of interphase heat transfer on the thermal convection of viscoelastic fluids in a porous medium are analyzed and discussed. The results show that the weak interphase heat transfer tends to stabilize the steady convection.

关键词: thermal convection     porous media     viscoelastic fluid     thermal nonequilibrium model    

Effect of gastric fluid on adsorption and desorption of endocrine disrupting chemicals on microplastics

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1525-8

摘要:

• Effect of gastric fluid on EDCs adsorption-desorption to microplastics was evaluated.

关键词: Microplastics     Gastric fluid     Endocrine-disrupting chemicals     Adsorption     Desorption    

Detection of digestive malignancies and post-gastrectomy complications via gastrointestinal fluid examination

null

《医学前沿(英文)》 2017年 第11卷 第1期   页码 20-31 doi: 10.1007/s11684-016-0493-4

摘要:

To date, gastric carcinoma (GC) is one of the common and fatal digestive malignancies worldwide. The prognosis of GC is not always satisfactory because of late diagnosis. Scholars are keen on discovering novel accurate and economical biomarkers in body liquids for GC screening to detect and evaluate the lesion before the results of imaging techniques are obtained. While traditional serum assays have limited sensitivity and specificity, gastrointestinal juice may provide relevant specific biomarkers because of its close contact with the tumor. Herein, the current progress in the relationship between gastrointestinal fluid analyses and GC is systematically and comprehensively reviewed. The detection of gastric juice pH, fluorescence spectrum, cytology, Helicobacter pylori-associated markers, nitrosamines, conventional tumor markers, amino acids, proteomics, microRNAs, long noncoding RNAs, protein-coding genes, vitamin C, etc., and combination tests of different category markers could provide important diagnostic and prognostic clues for gastrointestinal diseases. Particularly, early GC may be efficiently screened using gastric juice. Gastrointestinal fluid examination could also predict the adverse effects of postgastrectomy, such as pancreatic leakage, fistula, and abscess. Gastric fluid markers should be further studied to reveal the early predicators of malignancy and complications. The methods for obtaining the samples of gastrointestinal juice with minimum incision should also be comprehensively investigated.

关键词: gastrointestinal fluid     gastric carcinoma     biomarker     diagnosis     prognosis     gastrectomy     adverse events    

标题 作者 时间 类型 操作

Extended two-fluid model applied to analysis of bubbly flow in multiphase rotodynamic pump impeller

Zhiyi YU, Guoyu WANG, Shuliang CAO

期刊论文

Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

期刊论文

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid

期刊论文

Coupled solid-fluid FE-analysis of an embankment dam

Michael PERTL, Matthias HOFMANN, Guenter HOFSTETTER

期刊论文

Numerical simulation of fluid dynamics in the stirred tank by the SSG Reynolds Stress Model

Nana QI, Hui WANG, Kai ZHANG, Hu ZHANG

期刊论文

Thermal fluid-structure interaction and coupled thermal-stress analysis in a cable stayed bridge exposed

Nazim Abdul NARIMAN

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

Review of the LNG intermediate fluid vaporizer and its heat transfer characteristics

期刊论文

Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

期刊论文

Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

期刊论文

Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

期刊论文

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

Zhiqiang ZHANG , Aiqun LI , Jianping HE , Jianlei WANG ,

期刊论文

system for thermal convection of viscoelastic fluids in a porous layer using a thermal nonequilibrium model

Qi WEI, Xiaohui ZHANG

期刊论文

Effect of gastric fluid on adsorption and desorption of endocrine disrupting chemicals on microplastics

期刊论文

Detection of digestive malignancies and post-gastrectomy complications via gastrointestinal fluid examination

null

期刊论文