Simulations of Experiments on Isothermal Containment Atmosphere Mixing Caused by Vertical Injection

2020 ◽  
Author(s):  
Rok Krpan ◽  
Iztok Tiselj ◽  
Ivo Kljenak
Keyword(s):  
Best Practice ◽  
Molecular Diffusion ◽  
Numerical Models ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Correction Function ◽  
Best Practice Guidelines ◽  
Air Jet ◽  
Calculation Results ◽  
Definition Of

Abstract An experiment performed in SPARC experimental facility, was simulated with the computational fluid dynamics code OpenFOAM. The experiment took place in two phases. In the first phase, a helium-air layer was generated, which was then eroded with a vertical air jet injected in the vessel axis during the second experimental phase. A three-dimensional and a quasi-two-dimensional numerical models of a cylindrical vessel were developed and mesh convergence studies were performed. The mixing process was simulated as a single-phase flow with common momentum equation. Included gas species mass fractions are considered as passive scalars and are calculated using the transport equation. However, term describing the molecular diffusion cannot be neglected in our case and had to be added to diffusion equation implemented in default OpenFOAM solver. The k-ε turbulence model with additional buoyancy term implemented in OpenFOAM was used for turbulence modelling. Despite improvement of the physical model and following the Best Practice Guidelines, the results obtained with OpenFOAM CFD code still, at some locations, differ substantially from the experimental results. A modified definition of low Reynolds number eddy viscosity correction function is proposed, which significantly improves the agreement between measurements and calculation results.

scholarly journals Numerical Modelling of the Ultrasonic Treatment of Aluminium Melts: An Overview of Recent Advances

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3262 ◽  
Author(s):  
Bruno Lebon ◽  
Iakovos Tzanakis ◽  
Koulis Pericleous ◽  
Dmitry Eskin
Keyword(s):  
Best Practice ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
State Of The Art ◽  
Liquid Metals ◽  
Numerical Models ◽  
Acoustic Cavitation ◽  
Velocity Fields ◽  
Melt Processing ◽  
Best Practice Guidelines

The prediction of the acoustic pressure field and associated streaming is of paramount importance to ultrasonic melt processing. Hence, the last decade has witnessed the emergence of various numerical models for predicting acoustic pressures and velocity fields in liquid metals subject to ultrasonic excitation at large amplitudes. This paper summarizes recent research, arguably the state of the art, and suggests best practice guidelines in acoustic cavitation modelling as applied to aluminium melts. We also present the remaining challenges that are to be addressed to pave the way for a reliable and complete working numerical package that can assist in scaling up this promising technology.

scholarly journals Low-Cost Monitoring System of Sensors for Evaluating Dynamic Solicitations of Semitrailer Structure

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Pablo Luque ◽  
Daniel A. Mántaras ◽  
Aida Rodríguez ◽  
Hugo Malón ◽  
Luis Castejón ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Monitoring System ◽  
Extended Kalman Filter ◽  
Numerical Models ◽  
Low Cost ◽  
Three Dimensional ◽  
Cost Benefit ◽  
Simulation Software ◽  
Measurement Unit ◽  
Definition Of

Analysis of the fatigue life of a semitrailer structure necessitates identification of the loads and dynamic solicitations in the structure. These forces can be introduced in computer simulation software (multibody + finite element) for analysing the response of different design solutions to them. These numerical models must be validated and some parameters need to be measured directly in a field test with real vehicles under various driving conditions. In this study, a low-cost monitoring system is developed for application to a real fleet of semitrailers. According to the definition of the numerical model, the guidance of a virtual vehicle is defined by the three-dimensional kinematics of the kingpin. For characterisation of these movements, a monitoring system having a low-cost inertial measurement unit (IMU) and global positioning system (GPS) antennas is developed with different configurations to enable analysis of the best cost-benefit (result accuracy) solution, and an extended Kalman filter (EKF) that characterises the kinematic guidance of the kingpin is proposed. A semitrailer was equipped with the experimental low-cost monitoring system and high-precision sensors (IMU, GPS) in order to validate the results obtained by the experimental low-cost monitoring system and the inertial-extended Kalman filter developed. The validated system has applicability in the low-cost monitoring of a fleet of real vehicles.

Improving the Methodology for 3D Fluid-Thermal Analyses of Large-Bore Engine Cylinder Heads

2014 ◽  
Author(s):  
Stefano Toninel ◽  
Ian Calvert ◽  
Atanu Phukan
Keyword(s):  
Heat Transfer ◽  
Practice Guidelines ◽  
Cylinder Head ◽  
Best Practice ◽  
Development Process ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Water Jacket ◽  
Best Practice Guidelines ◽  
Engine Cylinder

Efficient use of three-dimensional CFD (Computational Fluid Dynamics) and CHT (Conjugate Heat Transfer) analyses is becoming increasingly critical, in order to compress the development process required for either on-going development, or the design of new large-bore engines for power generation applications. Engine performance and reliability targets force engine developers to progressively refine and screen design iterations, from the conceptual stage up to the design-freeze, by means of CAE (Computer Aided Engineering) methods, which have to be accurate, robust and cost-effective, in order for them to effectively contribute to the product design. An efficient deployment of these tools usually requires extensive efforts to consolidate the analysis procedures and allow loosening of particular accuracy requirements, in favor of a shorter overall turn-around time. Finally, validation of the models against measurements enables the definition of best-practice guidelines for future programs. The aim of this paper is to summarize the three-dimensional thermal-fluid simulation methodologies developed in GE’s Distributed Power business, for supporting the design of reciprocating engine cylinder-heads. The work reviews the two main types of analyses which are carried out during the defined development process. Isothermal simulations are performed in order to estimate the flow-field velocities in the cylinder-head water jacket, without modeling the wall heat-transfer. If backed up by consolidated guidelines, they can be highly efficient for down-selecting design variants, simply by looking at bulk results, with minimum requirements in terms of turbulence modeling. On the other end of the complexity spectrum, CHT simulations are used to model the thermal behavior of the cylinder-head assembly, by coupling and solving at run-time the RANS (Reynolds Averaged Navier-Stokes) equation set in the fluid domain and Fourier’s equation for the heat-transfer in the solid domain. The challenging timeline associated to a new engine development program induced the authors to carefully review and adapt, on a case-by-case basis, general CFD best-practice guidelines for near-wall turbulence modeling, well-established in the CFD community. This mitigation was driven by the high complexity of a typical water-jacket geometry and by a number of uncertainties in the real-world application, related to manufacturing tolerances, material properties and operating conditions, which should be considered in order to find the optimal trade-off between absolute accuracy and computational costs. Verification and validation CHT test-cases were carried out in order to support this approach. In particular, a comparison between the predicted CHT temperature solution and thermocouple measurements, performed on a GE Jenbacher engine, is described, in order to check the effectiveness of the proposed methodology and identifying opportunities for future developments.

A global assessment of basin plans: definitions, lessons, recommendations

Water Policy ◽  
2015 ◽  
Vol 18 (2) ◽  
pp. 368-386
Author(s):  
Jusipbek Kazbekov ◽  
Emelder Tagutanazvo ◽  
Jonathan Lautze
Keyword(s):  
Water Management ◽  
Water Quality ◽  
Global Assessment ◽  
Best Practice ◽  
Core Element ◽  
Developed Country ◽  
Best Practice Guidelines ◽  
Definition Of ◽  
And Coping ◽  
Water Quality And Quantity

Basin plans have become a core element of water management in the 21st century. Systematic analytical scrutiny of the contents of basin plans is nonetheless scant. This paper develops a framework for assessing basin plans and systematically applies it to understand how contents of basin plans vary. The paper synthesizes a definition of ‘basin plan’, generates a classification system for basin plans, and proceeds to classify a regionally diverse set of 23 basin plans. Major findings are that basin plans typically contain the components and sub-components suggested in best-practice guidelines. Focus on some issues that are presumably central to water management such as water quality and quantity is nonetheless comparatively low. Disaggregating basin plans suggests that developing-country transboundary plans are more geared towards hydropower development, navigation and coping with uncertainty, while developed-country and national plans appear to focus more on issues such as water quality and fish management. It is hoped that findings contained in this paper support future basin plan development by informing those crafting basin plans of the options available to them.

Terrestrial-LIDAR Visualization of Surface and Structural Deformations of the 2004 Niigata Ken Chuetsu, Japan, Earthquake

2006 ◽  
Vol 22 (1_suppl) ◽  
pp. 147-162 ◽  
Author(s):  
Robert Kayen ◽  
Robert T. Pack ◽  
James Bay ◽  
Shigetoshi Sugimoto ◽  
Hajime Tanaka
Keyword(s):  
High Resolution ◽  
Failure Modes ◽  
Numerical Models ◽  
Three Dimensional ◽  
High Resolution Data ◽  
Terrestrial Lidar ◽  
Digital Terrain ◽  
Structural Deformations ◽  
Definition Of ◽  
Deformation Patterns

Following the 23 October 2004 Niigata Ken Chuetsu, Japan, Mw 6.6 earthquake, LIDAR (light detection and ranging) technology was used to create ultra high-resolution three-dimensional digital terrain models of the earthquake damage. Two reconnaissance teams traveled with tripod-mounted LIDAR that allowed for the rapid collection of post-earthquake failure geometries of ground, structures, and lifelines prior to modification by post-disaster recovery efforts and natural processes, with range accuracies of approximately 2.5 cm and targets illuminated up to 400–700 m from the sensor. LIDAR offers several benefits: (1) detailed failure morphologies of damaged ground and structures, measured remotely and in a way not feasible by conventional means; (2) exploration and visualization of damage on a computer screen is enabled, in orientations and scales that were previously impossible, providing better definition of the failure surfaces, deformation patterns, and morphologies required for understanding failure modes; and (3) archived ultra-high-resolution data for evaluation of analytical and numerical models of deformation. High-resolution images and movies of LIDAR data can be viewed at http://walrus.wr.usgs.gov/geotech/Niigata/ and the online pages of Earthquake Spectra.

scholarly journals The level of endotoxins in hemodialysis water and dialysate in Lithuanian hemodialysis centers

Medicina ◽  
2010 ◽  
Vol 46 (8) ◽  
pp. 556 ◽  
Author(s):  
Inga Skarupskienė ◽  
Inga Bumblytė ◽  
Donatas Tamošaitis ◽  
Jūratė Venterienė ◽  
Vytautas Kuzminskis
Keyword(s):  
Best Practice ◽  
Dialysis Fluid ◽  
Membrane Pores ◽  
Best Practice Guidelines ◽  
Bacterial Endotoxins ◽  
Pass Through ◽  
Definition Of ◽  
Dialysis Water ◽  
Limulus Amebocyte Lysate Test

The composition and quality of the dialysis fluid play an important role in the modulation of dialysis-related complications. During hemodialysis, patient’s blood has a contact with dialysate through a semipermeable membrane. Bacterial endotoxins can pass through the membrane pores into the patient’s blood and cause a silent chronic microinflammation. The aim of this study was to determine the level of endotoxins in hemodialysis water and dialysate in Lithuanian hemodialysis centers. Dialysis water (n=50) and dialysate (n=50) were collected from 91% (n=50) of all hemodialysis centers. The presence of bacterial endotoxins was evaluated using a sensitive Limulus amebocyte lysate test, which detects intact lipopolysaccharides. The level of endotoxins was lower than 0.25 EU/mL in 43 (86%) dialysis water samples and in 46 (92%) dialysate samples, and complied with the recommendations of the European Pharmacopoeia and the European Best Practice Guidelines for pure dialysis fluid. The dialysate of 39 (78%) Lithuanian hemodialysis centers complied with the definition of an ultrapure dialysis fluid. The water and dialysate were of insufficient quality in 14% and in 8% of Lithuanian hemodialysis centers, respectively, and this could be improved by the establishment of routine investigation of endotoxins.

An Experimental Study on the Kerf Characteristics of Silicon Cut with Micro Abrasive Air Jet

2010 ◽  
Vol 135 ◽  
pp. 13-17 ◽  
Author(s):  
Quan Lai Li ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Hong Tao Zhu ◽  
Zeng Wen Liu
Keyword(s):  
Experimental Study ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Cutting Parameters ◽  
Traverse Speed ◽  
Parameters Optimization ◽  
Air Jet ◽  
Hard And Brittle Materials ◽  
Definition Of ◽  
Cutting Parameters Optimization

Micro abrasive air jet (MAAJ) cutting technology is being increasingly used in the precision machining of hard and brittle materials, due to its distinct advantages of negligible heat effect zone and small cutting force. In this paper, an experimental study on the kerf characteristics, especially for the effect of cutting parameters on the top edge definition, is presented. It shows that the top kerf edge is straight but not sharp. The top edge definition of the kerf improves with a decrease in the air pressure, while the effect of abrasive flow rate and nozzle traverse speed are hardly discernible. The optimum jet incidence angle for highest top edge definition of the kerf is 60°. The results of this paper may be useful for the cutting parameters optimization in the precision three-dimensional micro-structural machining.

Application of high-resolution field-emission LVSEM, backscatter imaging, immunogold staining to definition of the spatial distributions of two human neutrophil adherence receptors

1993 ◽  
Vol 51 ◽  
pp. 36-37
Author(s):  
Robert D. Nelson ◽  
Sharon R. Hasslen ◽  
Stanley L. Erlandsen
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Three Dimensional ◽  
Human Neutrophils ◽  
Spatial Distributions ◽  
Immunogold Staining ◽  
Functional Control ◽  
Neutrophil Adherence ◽  
Definition Of ◽  
Mode Of Attachment

Receptors are commonly defined in terms of number per cell, affinity for ligand, chemical structure, mode of attachment to the cell surface, and mechanism of signal transduction. We propose to show that knowledge of spatial distribution of receptors on the cell surface can provide additional clues to their function and components of functional control.L-selectin and Mac-1 denote two receptor populations on the neutrophil surface that mediate neutrophil-endothelial cell adherence interactions and provide for targeting of neutrophil recruitment to sites of inflammation. We have studied the spatial distributions of these receptors using LVSEM and backscatter imaging of isolated human neutrophils stained with mouse anti-receptor (primary) antibody and goat anti-mouse (secondary) antibody conjugated to 12 nm colloidal gold. This combination of techniques provides for three-dimensional analysis of the expression of these receptors on different surface membrane domains of the neutrophil: the ruffles and microvilli that project from the cell surface, and the cell body between these projecting structures.

Opioid crisis in primary care? An audit of high-dose opioid prescribing at Bangholm GP Practice

2020 ◽  
Vol 70 (suppl 1) ◽  
pp. bjgp20X711581
Author(s):  
Charlotte Greene ◽  
Alice Pearson
Keyword(s):  
Chronic Pain ◽  
Back Pain ◽  
Practice Guidelines ◽  
Best Practice ◽  
Evidence Base ◽  
High Dose ◽  
Opioid Prescription ◽  
Opioid Prescribing ◽  
Best Practice Guidelines

BackgroundOpioids are effective analgesics for acute and palliative pain, but there is no evidence base for long-term pain relief. They also carry considerable risks such as overdose and dependence. Despite this, they are increasingly prescribed for chronic pain. In the UK, opioid prescribing more than doubled between 1998 and 2018.AimAn audit at Bangholm GP Practice to understand the scale of high-strength opioid prescribing. The aim of the audit was to find out if indications, length of prescription, discussion, and documentation at initial consultation and review process were consistent with best-practice guidelines.MethodA search on Scottish Therapeutics Utility for patients prescribed an average daily dose of opioid equivalent ≥50 mg morphine between 1 July 2019 and 1 October 2019, excluding methadone, cancer pain, or palliative prescriptions. The Faculty of Pain Medicine’s best-practice guidelines were used.ResultsDemographics: 60 patients (37 females), average age 62, 28% registered with repeat opioid prescription, 38% comorbid depression. Length of prescription: average 6 years, 57% >5 years, 22% >10 years. Opioid: 52% tramadol, 23% on two opioids. Indications: back pain (42%), osteoarthritis (12%), fibromyalgia (10%). Initial consultation: 7% agreed outcomes, 35% follow-up documented. Review: 56% 4-week, 70% past year.ConclusionOpioid prescribing guidelines are not followed. The significant issues are: long-term prescriptions for chronic pain, especially back pain; new patients registering with repeat prescriptions; and no outcomes of treatment agreed, a crucial message is the goal is pain management rather than relief. Changes have been introduced at the practice: a patient information sheet, compulsory 1-month review for new patients on opioids, and in-surgery pain referrals.

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