Uncertainty in Computational Fluid Dynamics

1996 ◽  
Vol 210 (1) ◽  
pp. 91-94 ◽  
Author(s):  
E H Fisher ◽  
N Rhodes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Quality Assurance ◽  
Boundary Conditions ◽  
Error Estimation ◽  
Validation Studies ◽  
Postgraduate Training ◽  
Sources Of Uncertainty ◽  
Expert Meeting ◽  
Computational Fluid Dynamics Cfd

The Annual EPSRC/IMechE Expert Meeting brought together some 44 experts to consider sources of uncertainty in computational fluid dynamics (CFD). Presentations and discussions covered modelling, numerical solution techniques, boundary conditions, evaluation protocols and QA (quality assurance) procedures. The principal conclusions to emerge were: (a) the need for additional collaborative validation studies; (b) the desirability of introducing appropriate QA procedures, possibly based on the CFD Community Club initiative; (c) the need for additional postgraduate training, possibly based on the IGDS principle; (d) the value of continuing work in modelling and error estimation techniques for numerical schemes.

On the Use of Atmospheric Boundary Conditions for Axial-Flow Compressor Stall Simulations

2004 ◽  
Vol 127 (2) ◽  
pp. 349-351 ◽  
Author(s):  
M. Vahdati ◽  
A. I. Sayma ◽  
C. Freeman ◽  
M. Imregun
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Hysteresis Loop ◽  
Axial Flow ◽  
Computational Domain ◽  
Computational Fluid Dynamics Cfd ◽  
Fan Blade ◽  
Flow Compressor ◽  
Speed Characteristic

This paper describes a novel way of prescribing computational fluid dynamics (CFD) boundary conditions for axial-flow compressors. The approach is based on extending the standard single passage computational domain by adding an intake upstream and a variable nozzle downstream. Such a route allows us to consider any point on a given speed characteristic by simply modifying the nozzle area, the actual boundary conditions being set to atmospheric ones in all cases. Using a fan blade, it is shown that the method not only allows going past the stall point but also captures the typical hysteresis loop behavior of compressors.

Comparison of Particle-Wall Interaction Boundary Conditions in the Prediction of Cyclone Collection Efficiency in Computational Fluid Dynamics (CFD) Modeling

2010 ◽  
Vol 660-661 ◽  
pp. 158-163
Author(s):  
M.Ramirez Valverde ◽  
José Renato Coury ◽  
José Antônio Silveira Gonçalves
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Collection Efficiency ◽  
Cfd Modeling ◽  
Wall Boundary Conditions ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interaction

In recent years, many computational fluid dynamics (CFD) studies have appeared attempting to predict cyclone pressure drop and collection efficiency. While these studies have been able to predict pressure drop well, they have been only moderately successful in predicting collection efficiency. Part of the reason for this failure has been attributed to the relatively simple wall boundary conditions implemented in the commercially available CFD software, which are not capable of accurately describing the complex particle-wall interaction present in a cyclone. According, researches have proposed a number of different boundary conditions in order to improve the model performance. This work implemented the critical velocity boundary condition through a user defined function (UDF) in the Fluent software and compared its predictions both with experimental data and with the predictions obtained when using Fluent’s built-in boundary conditions. Experimental data was obtained from eight laboratory scale cyclones with varying geometric ratios. The CFD simulations were made using the software Fluent 6.3.26.

scholarly journals An Examination of the Relationship between Flow Parameters and Symptoms According to Fire Phase in a Mine Model

2017 ◽  
Vol 6 (2) ◽  
pp. 58
Author(s):  
Selçuk Keçel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Ventilation System ◽  
Underground Mine ◽  
Computational Fluid Dynamics Cfd ◽  
The Relationship

This study examines the relationship between temperature, CO dispersions, symptoms, and COHb% levels accumulated in the blood on available ventilation conditions in cases of fire at point in an underground mine model. Based on operating parameters (air velocity and direction) of the ventilation system in the underground mine model, fast growing phase fire analyses were conducted according to the heat release rate (HRR) value in the range of 0-61.34MW. In fire scenarios prepared according to the hydrocarbon fuel type (C2.3H4.2O1.3), boundary conditions were calculated depending on the combustion equation considering fuel lower heating value (Qc). CO dispersions inside the tunnel were examined by transferring the time-dependent boundary conditions to the computational fluid dynamics (CFD) program.  yCO, COHb%, and COHb%/∆t changes were calculated according to the HRR value.  Findings regarding the effects of CO emission (acute and chronic poisoning), were expressed according to the HRR value. Keywords Combustion Model Design, Heat Release Rate (HRR), Carbon Monoxide emission, Symptoms and Survival Time, Computational Fluid Dynamics (CFD);

Use of Computational Fluid Dynamics for the Replication of Clinical Blood Flow and Pressure Measurements and Characterization of Hemodynamics in the Normal Ascending and Thoracic Aorta

2007 ◽  
Author(s):  
John F. LaDisa ◽  
C. Alberto Figueroa ◽  
Irene E. Vignon-Clementel ◽  
Frandics P. Chan ◽  
Jeffrey A. Feinstein ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Thoracic Aorta ◽  
Vascular Anatomy ◽  
Data Set ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd

Complications associated with abnormalities of the ascending and thoracic aorta are directly influenced by mechanical forces. To understand hemodynamic alterations associated with diseases in this region, however, we must first characterize related indices during normal conditions. Computational fluid dynamics (CFD) models of the ascending and thoracic aorta to date have only provided descriptions of the velocity field using idealized representations of the vasculature, a single patient data set, and outlet boundary conditions that do not replicate physiologic blood flow and pressure. Importantly, the complexity of aortic flow patterns, limited availability of methods for implementing appropriate boundary conditions, and ability to replicate vascular anatomy all contribute to the difficulty of the problem and, likely, the scarcity of more detailed studies.

Effect of Inlet Boundary Conditions on Computational Fluid Dynamics (CFD) Simulations of Gas–Solid Flows in Risers

2011 ◽  
Vol 51 (4) ◽  
pp. 1721-1728 ◽  
Author(s):  
Milinkumar T. Shah ◽  
Ranjeet P. Utikar ◽  
Geoffrey M. Evans ◽  
Moses O. Tade ◽  
Vishnu K. Pareek
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd

scholarly journals Modelling Considerations in the Simulation of Hydrogen Dispersion within Tunnel Structures

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Idris Ismail ◽  
Hisayoshi Tsukikawa ◽  
Hiroshi Kanayama
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Hydrogen Gas ◽  
Convection Flow ◽  
Target Model ◽  
Computational Fluid Dynamics Cfd ◽  
Air Speed ◽  
Free Open Source ◽  
Limiting Value

The flow of leaked hydrogen gas in tunnel structures is simulated through a free, open source computational fluid dynamics (CFD) code for incompressible thermal convection flow. A one-fifth scale experimental model of a real tunnel is the target model to be simulated. To achieve this, studies on the effects of different boundary conditions, in particular, the wind speed, are carried out on smaller tunnel structures with the same hydrogen inlet boundary conditions. The results suggest a threshold/limiting value of air speed through tunnel. The target model computed with the most suitable boundary conditions shows some agreement with the experimental ones. A method to compute the buoyancy factor used in the code is also presented.

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