Numerical modeling for the effects of gravel permeability coefficient based on DEM and CFD method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anan Zhang ◽  
Jie Yang ◽  
Chuihui Ma ◽  
Lin Cheng ◽  
Liangcai Hu
Keyword(s):  
Permeability Coefficient ◽  
Fine Particles ◽  
Simulation Method ◽  
Test Sample ◽  
Treatment Method ◽  
Particle Model ◽  
Equal Weight ◽  
Content Type ◽  
Seepage Characteristics ◽  
Element Method

Purpose The purpose of this paper is to form a numerical simulation method for permeability coefficient that can consider the characteristics of gravel gradation and further explore the effects of indoor test factors and gradation characteristics on the permeability coefficient of gravel. Design/methodology/approach The random point method is used to establish the polyhedral gravel particle model, the discrete element method (DEM) is used to construct the gravel permeability test sample with gradation characteristics and the finite element method is used to calculate the permeability coefficient to form a DEM-computational fluid dynamics combined method to simulate the gravel seepage characteristics. Then, verified by the indoor test results. Based on this method, the influence of sample size, treatment method of oversize particles and the content of fine particles on the permeability coefficient of gravel is studied. Findings For the gravel containing large particles, the larger size permeameter should be used as far as possible. When the permeameter size is limited, the equal weight substitution method is recommended for the treatment method of oversized particles. Compared with the porosity, the pore connectivity has a higher correlation with the permeability coefficient of the sample. Research limitations/implications Insufficient consideration of the movement of gravel particles in the seepage process is also an issue for further study. Originality/value The simulation method described in this paper is helpful for qualitative analysis, quantitative expression of pore size and makes up for the defect that the seepage characteristics in pores cannot be observed in laboratory tests.

Thermo-mechanical coupling particle simulation of three-dimensional large-scale non-isothermal problems

2017 ◽  
Vol 34 (5) ◽  
pp. 1551-1571 ◽  
Author(s):  
Ming Xia
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Simulation Method ◽  
Particle Simulation ◽  
Similarity Criteria ◽  
Particle Model ◽  
Length Scale ◽  
Content Type ◽  
Mechanical Coupling ◽  
Particle Simulation Method

Purpose The main purpose of this paper is to present a comprehensive upscale theory of the thermo-mechanical coupling particle simulation for three-dimensional (3D) large-scale non-isothermal problems, so that a small 3D length-scale particle model can exactly reproduce the same mechanical and thermal results with that of a large 3D length-scale one. Design/methodology/approach The objective is achieved by following the scaling methodology proposed by Feng and Owen (2014). Findings After four basic physical quantities and their similarity-ratios are chosen, the derived quantities and its similarity-ratios can be derived from its dimensions. As the proposed comprehensive 3D upscale theory contains five similarity criteria, it reveals the intrinsic relationship between the particle-simulation solution obtained from a small 3D length-scale (e.g. a laboratory length-scale) model and that obtained from a large 3D length-scale (e.g. a geological length-scale) one. The scale invariance of the 3D interaction law in the thermo-mechanical coupled particle model is examined. The proposed 3D upscale theory is tested through two typical examples. Finally, a practical application example of 3D transient heat flow in a solid with constant heat flux is given to illustrate the performance of the proposed 3D upscale theory in the thermo-mechanical coupling particle simulation of 3D large-scale non-isothermal problems. Both the benchmark tests and application example are provided to demonstrate the correctness and usefulness of the proposed 3D upscale theory for simulating 3D non-isothermal problems using the particle simulation method. Originality/value The paper provides some important theoretical guidance to modeling 3D large-scale non-isothermal problems at both the engineering length-scale (i.e. the meter-scale) and the geological length-scale (i.e. the kilometer-scale) using the particle simulation method directly.

Modeling fine particles and alkali metal compound behavior in a kraft recovery boiler

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 9-14 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI ◽  
ANTTI OKSANEN
Keyword(s):  
Alkali Metal ◽  
Computational Models ◽  
Fine Particles ◽  
Black Liquor ◽  
Melting Behavior ◽  
Metal Compound ◽  
Effect Of Temperature ◽  
Particle Model ◽  
Boiler Furnace ◽  
Recovery Boiler

Under certain conditions, ash in black liquor forms a locally corrosive environment in a kraft recovery boiler. The ash also might cause efficiency losses and even boiler shutdown because of plugging of the flue gas passages. The most troublesome compounds in a fuel such as black liquor are potassium and chlorine because they change the melting behavior of the ash. Fouling and corrosion of the kraft recovery boiler have been researched extensively, but few computational models have been developed to deal with the subject. This report describes a computational fluid dynamics-based method for modeling the reactions between alkali metal compounds and for the formation of fine fume particles in a kraft recovery boiler furnace. The modeling method is developed from ANSYS/FLUENT software and its Fine Particle Model extension. We used the method to examine gaseous alkali metal compound and fine fume particle distributions in a kraft recovery boiler furnace. The effect of temperature and the boiler design on these variables, for example, can be predicted with the model. We also present some preliminary results obtained with the model. When the model is developed further, it can be extended to the superheater area of the kraft recovery boiler. This will give new insight into the variables that increase or decrease fouling and corrosion

Parallel finite-element method using domain decomposition and Parareal for transient motor starting analysis

2019 ◽  
Vol 38 (5) ◽  
pp. 1507-1520 ◽  
Author(s):  
Yasuhito Takahashi ◽  
Koji Fujiwara ◽  
Takeshi Iwashita ◽  
Hiroshi Nakashima
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Parallel Computing ◽  
Domain Decomposition ◽  
Parallel Computation ◽  
Domain Decomposition Method ◽  
Space Time ◽  
Content Type ◽  
Parallel Performance ◽  
Element Method

Purpose This paper aims to propose a parallel-in-space-time finite-element method (FEM) for transient motor starting analyses. Although the domain decomposition method (DDM) is suitable for solving large-scale problems and the parallel-in-time (PinT) integration method such as Parareal and time domain parallel FEM (TDPFEM) is effective for problems with a large number of time steps, their parallel performances get saturated as the number of processes increases. To overcome the difficulty, the hybrid approach in which both the DDM and PinT integration methods are used is investigated in a highly parallel computing environment. Design/methodology/approach First, the parallel performances of the DDM, Parareal and TDPFEM were compared because the scalability of these methods in highly parallel computation has not been deeply discussed. Then, the combination of the DDM and Parareal was investigated as a parallel-in-space-time FEM. The effectiveness of the developed method was demonstrated in transient starting analyses of induction motors. Findings The combination of Parareal with the DDM can improve the parallel performance in the case where the parallel performance of the DDM, TDPFEM or Parareal is saturated in highly parallel computation. In the case where the number of unknowns is large and the number of available processes is limited, the use of DDM is the most effective from the standpoint of computational cost. Originality/value This paper newly develops the parallel-in-space-time FEM and demonstrates its effectiveness in nonlinear magnetoquasistatic field analyses of electric machines. This finding is significantly important because a new direction of parallel computing techniques and great potential for its further development are clarified.

Information behaviour and decision-making in patients during their cancer journey

2017 ◽  
Vol 35 (3) ◽  
pp. 494-506 ◽  
Author(s):  
Shih-Chuan Chen
Keyword(s):  
Decision Making ◽  
Cancer Patients ◽  
Information Source ◽  
Alternative Therapy ◽  
Treatment Decision ◽  
Treatment Method ◽  
Structured Interviews ◽  
Content Type ◽  
Information Behaviour ◽  
Treatment Decision Making

Purpose This paper aims to investigate the effect of cancer patients’ information behaviour on their decision-making at the diagnosis and treatment stages of their cancer journey. Patients’ information sources and their decision-making approaches were analyzed. Design/methodology/approach Semi-structured interviews were conducted with 15 participants. Findings The cancer patients sought information from various sources in choosing a hospital, physician, treatment method, diet and alternative therapy. Physicians were the primary information source. The patients’ approaches to treatment decision-making were diverse. An informed approach was adopted by nine patients, a paternalistic approach by four and a shared decision-making approach by only two. Practical implications In practice, the findings may assist hospitals and medical professionals in fostering pertinent interactions with patients. Originality/value The findings can enhance researcher understanding regarding the effect of cancer patients’ information behaviour on their decision-making.

Effect of recess depth on lubrication performance of annular recess hydrostatic thrust bearing by constant rate flow

2018 ◽  
Vol 70 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Jun-peng Shao ◽  
Guang-dong Liu ◽  
Xiao-dong Yu ◽  
Yan-qin Zhang ◽  
Xiu-li Meng ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Simulation Method ◽  
Content Type ◽  
Oil Film ◽  
Constant Rate ◽  
Lubrication Performance ◽  
Optimal Value ◽  
Improved Performance ◽  
Lubrication Characteristics ◽  
Volume Method

Purpose The purpose of this paper is to describe a simulation and experimental research concerning the effect of recess depth on the lubrication performance of a hydrostatic thrust bearing by constant rate flow. Design/methodology/approach The computational fluid dynamics and finite volume method have been used to compute the lubrication characteristics of an annular recess hydrostatic thrust bearing with different recess depths. The performances are oil recess pressure, oil recess temperature and oil film velocity. The recess depth has been optimized. A test rig is established for testing the pressure field of the structure of hydrostatic thrust bearing after recess depth optimization, and experimental results show that experimental data are basically identical with the simulation results, which demonstrates the validity of the proposed numerical simulation method. Findings The results demonstrate that the oil film temperature decreases and the oil film pressure first increases and then decreases with an increase in the recess depth, but oil film velocity is constant. To sum up comprehensive lubrication performance, the recess depth of 3.5 mm is its optimal value for the annular recess hydrostatic thrust bearing. Originality/value The computed results indicate that to get an improved performance from a constant flow hydrostatic thrust bearing, a proper selection of the recess depth is essential.

Semi-analytical finite element method for simulating chemical dissolution-front instability problems in fluid-saturated porous media

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chongbin Zhao ◽  
B.E. Hobbs ◽  
Alison Ord
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Porous Media ◽  
Chemical Dissolution ◽  
Saturated Porous Media ◽  
Content Type ◽  
Front Instability ◽  
Fluid Saturated Porous Media ◽  
Dissolution Front ◽  
Element Method

PurposeThe objective of this paper is to develop a semi-analytical finite element method for solving chemical dissolution-front instability problems in fluid-saturated porous media.Design/methodology/approachThe porosity, horizontal and vertical components of the pore-fluid velocity and solute concentration are selected as four fundamental unknown variables for describing chemical dissolution-front instability problems in fluid-saturated porous media. To avoid the use of numerical integration, analytical solutions for the property matrices of a rectangular element are precisely derived in a purely mathematical manner. This means that the proposed finite element method is a kind of semi-analytical method. The column pivot element solver is used to solve the resulting finite element equations of the chemical dissolution-front instability problem.FindingsThe direct use of horizontal and vertical components of the pore-fluid velocity as fundamental unknown variables can improve the accuracy of the related numerical solution. The column pivot element solver is useful for solving the finite element equations of a chemical dissolution-front instability problem. The proposed semi-analytical finite element method can produce highly accurate numerical solutions for simulating chemical dissolution-front instability problems in fluid-saturated porous media.Originality/valueAnalytical solutions for the property matrices of a rectangular element are precisely derived for solving chemical dissolution-front instability problems in fluid-saturated porous media. The proposed semi-analytical finite element method provides a useful way for understanding the underlying dynamic mechanisms of the washing land method involved in the contaminated land remediation.

Numerical modelling of convection-diffusion problems with first-order chemical reaction using the dual reciprocity boundary element method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Salam Adel Al-Bayati ◽  
Luiz C. Wrobel
Keyword(s):  
Steady State ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Content Type ◽  
Convection Diffusion ◽  
First Order ◽  
Order Chemical Reaction ◽  
First Order Chemical Reaction ◽  
Diffusion Problems ◽  
Element Method

Purpose The purpose of this paper is to describe an extension of the boundary element method (BEM) and the dual reciprocity boundary element method (DRBEM) formulations developed for one- and two-dimensional steady-state problems, to analyse transient convection–diffusion problems associated with first-order chemical reaction. Design/methodology/approach The mathematical modelling has used a dual reciprocity approximation to transform the domain integrals arising in the transient equation into equivalent boundary integrals. The integral representation formula for the corresponding problem is obtained from the Green’s second identity, using the fundamental solution of the corresponding steady-state equation with constant coefficients. The finite difference method is used to simulate the time evolution procedure for solving the resulting system of equations. Three different radial basis functions have been successfully implemented to increase the accuracy of the solution and improving the rate of convergence. Findings The numerical results obtained demonstrate the excellent agreement with the analytical solutions to establish the validity of the proposed approach and to confirm its efficiency. Originality/value Finally, the proposed BEM and DRBEM numerical solutions have not displayed any artificial diffusion, oscillatory behaviour or damping of the wave front, as appears in other different numerical methods.

Design modification of iron ore bearing transfer chute using discrete element method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Saprativ Basu ◽  
Arijit Chakrabarty ◽  
Samik Nag ◽  
Kishore Behera ◽  
Brati Bandyopadhyay ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Iron Ore ◽  
Bulk Material ◽  
Flow Behavior ◽  
Material Model ◽  
Discrete Element ◽  
Content Type ◽  
Iron Ore Fines ◽  
Cohesive Materials ◽  
Element Method

Purpose The dryer feed chute of the pellet plant plays an important role in the pelletizing process. The chute discharges sticky and moist iron ore fines (<1 mm) to the inline rotary dryer for further processing. Since the inception of the installation of the dryer feed chute, the poor flowability of the feed materials has caused severe problems such as blockages and excessive wear of chute liners. This leads to high maintenance costs and reduced lifetime of the liner materials. Constant housekeeping is needed for maintaining the chute and reliable operation. The purpose of this study is to redesign the dryer feed chute to overcome the above challenges. Design/methodology/approach The discrete element method (DEM) has been used to model the flow of cohesive materials through the transfer chute. Physical experiments have been performed to understand the most severe flow conditions. A DEM material model is also developed for replicating the worst-case material condition. After identifying the key problem areas, concept designs were proposed and simulated to assess the design improvements to increase the reliability of chute operation. Findings Flow simulations correlated well with the existing flow behavior of the iron ore fines inside the chute. The location of the problematic areas has been validated with that of the previously installed chute. Subsequently, design modifications have been proposed. This includes modification of deflector plate and change in slope and cross-section of the chute. DEM simulations and analysis were conducted after incorporating these design changes. A comparison in the average velocity of particle and force on chute wall shows a significant improvement using the proposed design. Originality/value Method to calibrate DEM material model was found to provide accurate prediction and modeling of the flow behavior of bulk material through the real transfer chute. DEM provided greater insight into the performance of the chute especially modeling cohesive materials. DEM is a valuable design tool to assist chute designers troubleshoot and verify chute designs. DEM provides a greater ability to model and assess chute wear. This technique can help in achieving a scientific understanding of the flow properties of bulk solids through transfer chute, hence eliminate challenges, ensuring reliable, uninterrupted and profitable plant operation. This paper strongly advocates the use of calibrated DEM methodology in designing bulk material handling equipment.

Sustainability assessment model for heritage buildings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abobakr Al-Sakkaf ◽  
Ashutosh Bagchi ◽  
Tarek Zayed ◽  
Sherif Mahmoud
Keyword(s):  
Case Studies ◽  
Rating Scale ◽  
Sustainability Assessment ◽  
Model Development ◽  
Assessment Model ◽  
Equal Weight ◽  
Indoor Environmental Quality ◽  
Regional Variations ◽  
Content Type ◽  
Heritage Buildings

PurposeThe purpose of this research is to focus on the evaluation of heritage buildings' sustainability. BIM modeling was necessary for the design of the sustainability assessment model for Heritage Buildings (SAHB). Using ArchiCAD®, energy simulations were performed for two case studies (Murabba Palace, Saudi Arabia, and Grey Nuns Building, Canada), and the developed model was validated through sensitivity analysis.Design/methodology/approachHeritage buildings (HBs) are unique and must be preserved for future generations. This article focuses on a sustainability assessment model and rating scale for heritage buildings in light of the need for their conservation. Regional variations were considered in the model development to identify critical attributes whose corresponding weights were then determined by fuzzy logic. Data was collected via questionnaires completed by Saudi Arabian and Canadian experts, and Fuzzy TOPSIS was also applied to eliminate the uncertainties present when human opinions are involved.FindingsResults showed that regional variations were sufficiently addressed through the multi-level weight consideration in the proposed model. Comparing the nine identified factors that affect the sustainability of HBs, energy and indoor environmental quality were of equal weight in both case studies.Originality/valueThis study will be helpful for the design of a globally applicable sustainability assessment model for HBs. It will also enable decision-makers to prepare maintenance plans for HBs.

scholarly journals Establishment and Application of Rapid Diagnosis for Reverse Transcription-Quantitative PCR of Newly Emerging Goose-Origin Nephrotic Astrovirus in China

mSphere ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Xiaoyuan Yuan ◽  
Kai Meng ◽  
Yuxia Zhang ◽  
Lihong Qi ◽  
Wu Ai ◽  
...  
Keyword(s):  
Quantitative Pcr ◽  
Clinical Application ◽  
Reverse Transcription ◽  
Test Sample ◽  
Sensitivity Testing ◽  
Content Type ◽  
Reverse Transcription Quantitative Pcr ◽  
Emerging Virus ◽  
New Type ◽  
And Control

ABSTRACT In 2017, a new type of goose-origin astrovirus (GoAstV) that is completely different from previously identified avian astroviruses (which have only 30.0% to 50.5% homology with GoAstV) has been isolated from diseased geese in China. This disease can cause joint swelling in sick geese, and the anatomy shows a clear precipitation of urate in the kidney. The rate of death and culling can reach more than 30%, revealing the disease’s severe pathogenicity. To quickly and accurately diagnose the newly emerging disease, we established a highly specific reverse transcription-quantitative PCR (RT-qPCR) method of detecting GoAstV. Sensitivity testing showed that the minimum amount of test sample for this method is 52.5 copies/μl. Clinical application confirmed that this method can quickly and effectively detect GoAstV, providing a diagnostic platform for the prevention and control of goose disease. IMPORTANCE Goose-origin astrovirus (GoAstV), as a newly emerging virus in 2017, is different from previously known astroviruses in the genus Avastrovirus. So far, few studies have focused on the novel virus. Considering the infectious development of astrovirus (AstV), we established a reverse transcription-quantitative PCR (RT-qPCR) assay with a strong specificity to quickly and accurately diagnose GoAstV. Confirmed by clinical application, this method can quickly and accurately detect prevalent GoAstV. The assay is thus convenient for clinical operation and is applicable to the monitoring of GoAstV disease.

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