scholarly journals Synthesis of a CFD Benchmark Exercise: Examining Fluid Flow and Residence-Time Distribution in a Water Model of Tundish

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5453
Author(s):  
Dong-Yuan Sheng
Keyword(s):  
Best Practice ◽  
Model Development ◽  
Practical Interest ◽  
Turbulence Models ◽  
Fluid Simulation ◽  
Model Verification ◽  
Water Model ◽  
Cfd Simulations ◽  
Cfd Models ◽  
Selection Of

Computational Fluid Dynamics (CFD) has become an indispensable tool that can potentially predict many phenomena of practical interest in the tundish. Model verification and validation (V&V) are essential parts of a CFD model development process if the models are to be used with sufficient confidence in real industrial tundish applications. The crucial aspects of CFD simulations in the tundish are addressed in this study, such as the selection of the turbulence models, meshing, boundary conditions, and selection of discretization schemes. A series of CFD benchmarking exercises are presented serving as selected examples of appropriate modelling strategies. A tundish database, initiated by German Steel Institute VDEH working group “Fluid Mechanics and Fluid Simulation”, was revisited with the aim of establishing a comprehensive set of best practice guidelines (BPG) in CFD simulations for tundish applications. These CFD benchmark exercises yield important results for the sensible application of CFD models and contribute to further improving the reliability of CFD applications in metallurgical reactors.

Validation of CFD simulations for X-31 wind-tunnel models

2015 ◽  
Vol 119 (1214) ◽  
pp. 479-500 ◽  
Author(s):  
M. Ghoreyshi ◽  
A. D. H. Kim ◽  
A. Jirasek ◽  
A. J. Lofthouse ◽  
R. M. Cummings
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Force ◽  
Numerical Algorithms ◽  
Turbulence Models ◽  
Leading Edge ◽  
Convergence Acceleration ◽  
Cfd Simulations ◽  
Data Set ◽  
Cfd Models ◽  
Sinusoidal Oscillations

AbstractComputational Fluid Dynamics (CFD) has become an attractive method of choice in the design of many aerospace vehicles because of advances in numerical algorithms and convergence acceleration methods. However, the flow around an advanced fighter aircraft is complicated and usually unsteady due to the presence of vortex-dominated flows. The accuracy and predictability of conventional turbulence models for these applications may be questionable and therefore results obtained from these models must be validated and evaluated on the basis of experimental data from wind tunnels and/or flight tests. This work aims to validate CFD simulations of X-31 wind-tunnel models with and without a belly-mounted sting. The sting setup facilitates forced sinusoidal oscillations in one of three modes of: pitch, yaw, and roll. However, the results show that measured aerodynamic data are altered by the turbulent wake behind the sting, even at small angles of attack. The high angle-of-attack flow around the X-31 is also very complicated and unsteady due to canard and wing vortices. Therefore, validation of CFD models for predicting these complex flows can be a very challenging task. The X-31 wind-tunnel experiments were carried out in the German Dutch low-speed wind tunnel at Braunschweig and include aerodynamic force and moment measurement as well as span-wise pressure distributions at locations of 60% and 70% chord length. This data set is used to validate the Cobalt and Kestrel flow solvers and the results are similar and match quiet well with experiments for small to moderate angles of attack. The main discrepancies between CFD and measurements occur close to the wing tip, where leading-edge flaps are located.

Performance enhancement of Savonius wind turbine by blade shape and twisted angle modifications

2021 ◽  
pp. 095765092098794
Author(s):  
Ahmed M Nagib Elmekawy ◽  
Hassan A Hassan Saeed ◽  
Sadek Z Kassab
Keyword(s):  
Wind Turbine ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Cfd Simulations ◽  
Sliding Mesh ◽  
Blade Shape ◽  
Rotor Shape ◽  
Twisting Angle

Three-dimensional CFD simulations are carried out to study the increase of power generated from Savonius vertical axis wind turbines by modifying the blade shape and blade angel of twist. Twisting angle of the classical blade are varied and several proposed novel blade shapes are introduced to enhance the performance of the wind turbine. CFD simulations have been performed using sliding mesh technique of ANSYS software. Four turbulence models; realizable k -[Formula: see text], standard k - [Formula: see text], SST transition and SST k -[Formula: see text] are utilized in the simulations. The blade twisting angle has been modified for the proposed dimensions and wind speed. The introduced novel blade increased the power generated compared to the classical shapes. The two proposed novel blades achieved better power coefficients. One of the proposed models achieved an increase of 31% and the other one achieved 32.2% when compared to the classical rotor shape. The optimum twist angel for the two proposed models achieved 5.66% and 5.69% when compared with zero angle of twist.

scholarly journals Artistic Freedom or Animal Cruelty? Contemporary Visual Art Practice That Involves Live and Deceased Animals

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 812
Author(s):  
Ellie Coleman ◽  
Rebecca Scollen ◽  
Beata Batorowicz ◽  
David Akenson
Keyword(s):  
Best Practice ◽  
Animal Cruelty ◽  
Art Practice ◽  
Animal Protection ◽  
Ethical Implications ◽  
High Profile ◽  
Unethical Practices ◽  
Artistic Freedom ◽  
Legal Guidelines ◽  
Selection Of

This paper examines a selection of 21st-century international examples of exhibited visual artworks involving live or deceased animals. It seeks to reveal the risks and benefits of unique encounters with animals through art and to consider the ethical implications of artwork deploying animals. Australian and international animal protection laws are not explicit when it comes to the sourcing of animals for art nor for the direct inclusion of animals in artworks. This lack leads to a variety of artistic practices, some considered ethical while others are viewed as controversial, bordering on animal cruelty. Artwork selection is determined by a focus on high-profile artists who intentionally use animals in their practice and whose reputation has been fostered by this intention. The study provides insight into how the intentional use of ethically sourced animals within art practice can be a method of addressing hierarchal human–animal imbalances. Further, this study identifies unethical practices that may be best avoided regardless of the pro-animal political statements the artists put forward. Recommendations of how to better determine what is an acceptable use of animals in art with a view to informing legal guidelines and artistic best practice are presented.

scholarly journals Spatial-Planning-Based Ecosystem Adaptation (SPBEA): A Concept and Modeling of Prone Shoreline Retreat Areas

2021 ◽  
Vol 10 (3) ◽  
pp. 176
Author(s):  
Dewayany Sutrisno ◽  
Mulyanto Darmawan ◽  
Ati Rahadiati ◽  
Muhammad Helmi ◽  
Armaiki Yusmur ◽  
...  
Keyword(s):  
Spatial Planning ◽  
Best Practice ◽  
Model Development ◽  
Multicriteria Analysis ◽  
Climate Change Impacts ◽  
Coastal Protection ◽  
Adaptation To Climate Change ◽  
Shoreline Retreat ◽  
Tidal Waves ◽  
Central Java

Ecosystem-based adaptation to climate change impacts, such as shoreline retreat, has been promoted at the international, national, and even local levels. However, among scientists, opinions about how to implement it in spatial-planning practices are varied. Science-based environmental factors, human wellbeing, and sustainable development can be strengthened by developing spatial-planning-based ecosystem adaptations (SPBEAs). Therefore, this article aims to assess how the SPBEA model can be developed within an area prone to shoreline retreat. A coastal area of the Sayung subdistrict in Central Java, Indonesia, was selected as a study area because it has experienced a massive shoreline retreat. A multicriteria analysis (MCA) method was employed for developing the model by using the geographic information system (GIS) technique of analysis, divided into three steps: the fishpond zone determination, which involved the analytical hierarchy process (AHP) method in the process of model development; the fishpond site determination; SPBEA fishpond site development. The results show that the SPBEA model is the best practice solution for combatting shoreline retreat because of tidal waves and/or sea-level rise. The spatial site management should empower the coastal protection zone and the sustainable fishpond zone by implementing a silvofishery approach.

scholarly journals Consensus for the General Use of Equine Water Treadmills for Healthy Horses

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 305
Author(s):  
Kathryn Nankervis ◽  
Carolyne Tranquille ◽  
Persephone McCrae ◽  
Jessica York ◽  
Morgan Lashley ◽  
...  
Keyword(s):  
Working Group ◽  
Best Practice ◽  
Treadmill Exercise ◽  
Good Practice ◽  
Belt Speed ◽  
Research Programmes ◽  
Potential Benefits ◽  
Water Treadmill ◽  
Selection Of

Water treadmill exercise has become popular in recent years for the training and rehabilitation of equine athletes. In 2019, an equine hydrotherapy working group was formed to establish what was commonly considered to be best practice in the use of the modality. This article describes the process by which general guidelines for the application of water treadmill exercise in training and rehabilitation programmes were produced by the working group. The guidelines describe the consensus reached to date on (1) the potential benefits of water treadmill exercise, (2) general good practice in water treadmill exercise, (3) introduction of horses to the exercise, (4) factors influencing selection of belt speed, water depth and duration of exercise, and (5) monitoring movement on the water treadmill. The long-term goal is to reach a consensus on the optimal use of the modality within a training or rehabilitation programme. Collaboration between clinicians, researchers and experienced users is needed to develop research programmes and further guidelines regarding the most appropriate application of the modality for specific veterinary conditions.

A Model Constraint for Polydisperse Solids in Multifluid Flows

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Michael P. Kinzel ◽  
Leonard Joel Peltier ◽  
Brigette Rosendall ◽  
Mallory Elbert ◽  
Andri Rizhakov ◽  
...  
Keyword(s):  
Model Development ◽  
Fluid Flows ◽  
Momentum Exchange ◽  
Carrier Fluid ◽  
Single Carrier ◽  
Cfd Models ◽  
Model Constraint ◽  
Level Model ◽  
Consistency Constraint ◽  
Multiphase Fluid

A method to assess computational fluid dynamics (CFD) models for polydisperse granular solids in a multifluid flow is developed. The proposed method evaluates a consistency constraint, or a condition that an Eulerian multiphase solution for a monodisperse material in a single carrier fluid is invariant to an arbitrary decomposition into a pseudo-polydisperse mixture of multiple, identical fluid phases. The intent of this condition is to develop tests to assist model development and testing for multiphase fluid flows. When applied to two common momentum exchange models, the constraint highlights model failures for polydisperse solids interacting with a multifluid flow. It is found that when inconsistency occurs at the algebraic level, model failure clearly extends to application. When the models are reformulated to satisfy the consistency constraint, simple tests and application-scale simulations no longer display consistency failure.

A systematic approach for model verification: application on seven published activated sludge models

2010 ◽  
Vol 61 (4) ◽  
pp. 825-839 ◽  
Author(s):  
H. Hauduc ◽  
L. Rieger ◽  
I. Takács ◽  
A. Héduit ◽  
P. A. Vanrolleghem ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Systematic Approach ◽  
Model Development ◽  
Model Verification ◽  
Software Implementation ◽  
Model Description ◽  
Kinetic Rate ◽  
Simulation Results ◽  
Activated Sludge Models

The quality of simulation results can be significantly affected by errors in the published model (typing, inconsistencies, gaps or conceptual errors) and/or in the underlying numerical model description. Seven of the most commonly used activated sludge models have been investigated to point out the typing errors, inconsistencies and gaps in the model publications: ASM1; ASM2d; ASM3; ASM3 + Bio-P; ASM2d + TUD; New General; UCTPHO+. A systematic approach to verify models by tracking typing errors and inconsistencies in model development and software implementation is proposed. Then, stoichiometry and kinetic rate expressions are checked for each model and the errors found are reported in detail. An attached spreadsheet (see http://www.iwaponline.com/wst/06104/0898.pdf) provides corrected matrices with the calculations of all stoichiometric coefficients for the discussed biokinetic models and gives an example of proper continuity checks.

scholarly journals Catheter placement selection for convection-enhanced delivery of therapeutic agents to brain tumors

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1415
Author(s):  
Lisa H. Antoine ◽  
Roy P. Koomullil ◽  
Timothy M. Wick ◽  
Louis B. Nabors ◽  
Ahmed K. Abdel Aal ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Tumor Volume ◽  
Therapeutic Agents ◽  
Catheter Placement ◽  
Volume Distribution ◽  
Convection Enhanced Delivery ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Magnetic Resonance Imaging Mri ◽  
Selection Of

Background: Convection-enhanced delivery (CED) of therapeutic agents to brain tumors allows clinicians to bypass the blood-brain barrier (BBB) to infuse virus therapy, biological, or chemotherapy directly into a brain tumor through convection. However, the effectiveness of infusions via CED may depend on catheter placement. Methods: This study used diffusion maps from magnetic resonance imaging (MRI) of human brain tumors and computational fluid dynamics (CFD) simulations to assess therapy volume distribution percentages based on catheter placement locations. Results: The primary outcome showed differences in volume distribution based on the catheter placement location. Total tumor volume filled ranged from 144.40 mm3 to 317.98 mm3. Percent filled of tumor volume ranged from 2.87% to 6.32%. Conclusions: The selection of the location for catheter placement using the region with the highest volume filled may provide optimal therapeutic effect.  The researchers conclude that CFD may provide guidance for catheter placement in CED of therapeutic agents.

scholarly journals Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

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