Points to Note in Modeling Fire With Computational Fluid Dynamics

2012 ◽  
Author(s):  
L. Qu ◽  
W. K. Chow
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Design Tool ◽  
Performance Based Design ◽  
Cfd Model ◽  
Fire Dynamics ◽  
Design Fire ◽  
Computational Fluid Dynamics Cfd ◽  
Three Dimensional Simulations

Computational Fluid Dynamics (CFD) is a popular design tool in many projects for ensuring fire safety through performance-based design. However, there are always challenges on the quality and uncertainties of the CFD simulated results. Two points raised are on the grid size and free boundary conditions. A simple corridor fire with a small design fire is taken as an example to address these two points in this paper. The CFD model Fire Dynamics Simulator (FDS) version 5 was taken as the simulation tool Two-dimensional and three-dimensional simulations are compared. The geometry is proposed to outside for better description on minimizing opening boundary.

Development and Validation of a 3-Dimensional Computational Fluid Dynamics (CFD) Model for Rectangular Settling Tanks in New York City Water Pollution Control Plants

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
K. Ramalingam ◽  
J. Fillos ◽  
S. Xanthos ◽  
M. Gong ◽  
A. Deur ◽  
...  
Keyword(s):  
Water Pollution ◽  
Fluid Dynamics ◽  
New York ◽  
Computational Fluid Dynamics ◽  
New York City ◽  
Pollution Control ◽  
York City ◽  
Three Dimensional ◽  
Cfd Model ◽  
Computational Fluid Dynamics Cfd

New York City provides secondary treatment to approximately 78.6 m3/s among its 14 water pollution control plants (WPCPs). The process of choice has been step-feed activated sludge. Changes to the permit limits require nitrogen removal in WPCPs discharging into the Long Island Sound. The City has selected step feed biological nitrogen removal (BNR) process to upgrade the affected plants. Step feed BNR requires increasing the concentration of mixed liquors, (MLSS), which stresses the Gould II type rectangular final settling tanks (FSTs). To assess performance and evaluate alternatives to improve efficiency of the FSTs at the higher loads, New York City Department of Environmental Protection (NYCDEP) and City College of New York (CCNY) have developed a three-dimensional computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Using Computational Fluid Dynamics (CFD) Model, Fluent 6.3.26TM as the base platform, sub-models of the SS settling characteristics as well as turbulence, flocculation, etc. were incorporated. This was supplemented by field and bench scale experiments to quantify the co-efficients integral to the sub-models. As a result, a three-dimensional model has been developed that is being used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs.

Transient Analysis of a Spring-Loaded Pressure Safety Valve Using Computational Fluid Dynamics (CFD)

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Xue Guan Song ◽  
Lin Wang ◽  
Young Chul Park
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Safety Valve ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Moving Mesh ◽  
Cfd Model ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd ◽  
Mesh Technique

A spring-loaded pressure safety valve (PSV) is a key device used to protect pressure vessels and systems. This paper developed a three-dimensional computational fluid dynamics (CFD) model in combination with a dynamics equation to study the fluid characteristics and dynamic behavior of a spring-loaded PSV. The CFD model, which includes unsteady analysis and a moving mesh technique, was developed to predict the flow field through the valve and calculate the flow force acting on the disk versus time. To overcome the limitation that the moving mesh technique in the commercial software program ANSYS CFX (Version 11.0, ANSYS, Inc., USA) cannot handle complex configurations in most applications, some novel techniques of mesh generation and modeling were used to ensure that the valve disk can move upward and downward successfully without negative mesh error. Subsequently, several constant inlet pressure loads were applied to the developed model. Response parameters, including the displacement of the disk, mass flow through the valve, and fluid force applied on the disk, were obtained and compared with the study of the behavior of the PSV under different overpressure conditions. In addition, the modeling approach could be useful for valve designers attempting to optimize spring-loaded PSVs.

Extent, capacity and possibilities of computational fluid dynamics as a design tool for pump intakes: a review

2018 ◽  
Vol 18 (5) ◽  
pp. 1518-1530 ◽  
Author(s):  
Jie Zhang ◽  
Tien Yee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Design Tool ◽  
Cfd Modeling ◽  
Cfd Simulations ◽  
Pump Station ◽  
Computational Fluid Dynamics Cfd ◽  
Future Direction ◽  
Computational Resources

Abstract Flow near pump intakes is three-dimensional in nature, and is affected by many factors such as the geometry of the intake bay, uniformity of approach flow, critical submergence, placements and operation combinations of pumps and so on. In the last three decades, advancement of numerical techniques coupled with the increase in computational resources made it possible to conduct computational fluid dynamics (CFD) simulations on pump intakes. This article reviews different aspects involved in CFD modeling of pump station intakes, outlines the challenges faced by current CFD modelers, and provides an attempt to forecast future direction of CFD modeling of pump intakes.

scholarly journals The use of CFD in the evaluation of UV treatment systems

2001 ◽  
Vol 3 (2) ◽  
pp. 59-70 ◽  
Author(s):  
N. G. Wright ◽  
D. M. Hargreaves
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Grid Size ◽  
Design Tool ◽  
Uv Disinfection ◽  
Efficient Design ◽  
Uv Treatment ◽  
Sensitivity Tests ◽  
Computational Fluid Dynamics Cfd

UV disinfection is now widely used for the treatment of water for consumption and wastewater in many countries. It offers advantages over other techniques in specific circumstances. Analysis of these systems has been carried out using a three-dimensional Computational Fluid Dynamics (CFD) procedure. This allows for efficient testing of prototypes. Sensitivity tests are shown for grid size, discretisation and turbulence model. Four different configurations of the apparatus are evaluated in terms of maximum dosage, flow patterns, particle tracks and transient dosage. This leads to conclusions about the most efficient design and shows that significant improvements can be achieved with minor changes to the design. Further conclusions are drawn about the CFD procedure itself. This work opens up the possibility of an internet-based design tool for small- and medium-sized enterprises.

Investigation of the Effect of Fuel Reactivity on Dual-Fuel PCI Combustion

2012 ◽  
Vol 588-589 ◽  
pp. 287-290
Author(s):  
Li Jun Ou ◽  
Chun Mei Wang ◽  
Hui Chun Wang ◽  
Su Wei Zhu ◽  
Ye Jian Qian
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Exhaust Emissions ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Cfd Model ◽  
Ignition Timing ◽  
Computational Fluid Dynamics Cfd

The potential of controlling premixed compression ignition (PCI) combustion by two fuels with different ignitability and volatility was studied numerically by a three-dimensional computational fluid dynamics (CFD) model. The results indicate that the addition of gasoline to diesel fueled PCI engine can retard the ignition timing, lower the in-cylinder temperature, and reduce the exhaust emissions.

Validation of a Computationally Efficient Computational Fluid Dynamics (CFD) Model for Industrial Bubble Column Bioreactors

2014 ◽  
Vol 53 (37) ◽  
pp. 14526-14543 ◽  
Author(s):  
Dale D. McClure ◽  
Hannah Norris ◽  
John M. Kavanagh ◽  
David F. Fletcher ◽  
Geoffrey W. Barton
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Bubble Column ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Computational Fluid Dynamics Cfd

scholarly journals Journal Bearing: An Integrated CFD-Analytical Approach for the Estimation of the Trajectory and Equilibrium Position

2020 ◽  
Vol 10 (23) ◽  
pp. 8573
Author(s):  
Franco Concli
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Distribution ◽  
Equilibrium Position ◽  
Analytical Approach ◽  
Journal Bearing ◽  
Cfd Model ◽  
Cavitation Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Mathematical Model

For decades, journal bearings have been designed based on the half-Sommerfeld equations. The semi-analytical solution of the conservation equations for mass and momentum leads to the pressure distribution along the journal. However, this approach admits negative values for the pressure, phenomenon without experimental evidence. To overcome this, negative values of the pressure are artificially substituted with the vaporization pressure. This hypothesis leads to reasonable results, even if for a deeper understanding of the physics behind the lubrication and the supporting effects, cavitation should be considered and included in the mathematical model. In a previous paper, the author has already shown the capability of computational fluid dynamics to accurately reproduce the experimental evidences including the Kunz cavitation model in the calculations. The computational fluid dynamics (CFD) results were compared in terms of pressure distribution with experimental data coming from different configurations. The CFD model was coupled with an analytical approach in order to calculate the equilibrium position and the trajectory of the journal. Specifically, the approach was used to study a bearing that was designed to operate within tight tolerances and speeds up to almost 30,000 rpm for operation in a gearbox.

An Improved Computational Fluid Dynamics (CFD) Model for Erosion Prediction in Oil and Gas Industry Applications

2014 ◽  
Author(s):  
Deval Pandya ◽  
Brian Dennis ◽  
Ronnie Russell
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Surface Velocity ◽  
Particle Model ◽  
Model Parameters ◽  
Cfd Model ◽  
Erosion Model ◽  
Erosion Prediction ◽  
Erosion Models ◽  
Computational Fluid Dynamics Cfd

In recent years, the study of flow-induced erosion phenomena has gained interest as erosion has a direct influence on the life, reliability and safety of equipment. Particularly significant erosion can occur inside the drilling tool components caused by the low particle loading (<10%) in the drilling fluid. Due to the difficulty and cost of conducting experiments, significant efforts have been invested in numerical predictive tools to understand and mitigate erosion within drilling tools. Computational fluid dynamics (CFD) is becoming a powerful tool to predict complex flow-erosion and a cost-effective method to re-design drilling equipment for mitigating erosion. Existing CFD-based erosion models predict erosion regions fairly accurately, but these models have poor reliability when it comes to quantitative predictions. In many cases, the error can be greater than an order of magnitude. The present study focuses on development of an improved CFD-erosion model for predicting the qualitative as well as the quantitative aspects of erosion. A finite-volume based CFD-erosion model was developed using a commercially available CFD code. The CFD model involves fluid flow and turbulence modeling, particle tracking, and application of existing empirical erosion models. All parameters like surface velocity, particle concentration, particle volume fraction, etc., used in empirical erosion equations are obtained through CFD analysis. CFD modeling parameters like numerical schemes, turbulence models, near-wall treatments, grid strategy and discrete particle model parameters were investigated in detail to develop guidelines for erosion prediction. As part of this effort, the effect of computed results showed good qualitative and quantitative agreement for the benchmark case of flow through an elbow at different flow rates and particle sizes. This paper proposes a new/modified erosion model. The combination of an improved CFD methodology and a new erosion model provides a novel computational approach that accurately predicts the location and magnitude of erosion. Reliable predictive methodology can help improve designs of downhole equipment to mitigate erosion risk as well as provide guidance on repair and maintenance intervals. This will eventually lead to improvement in the reliability and safety of downhole tool operation.

Sign in / Sign up

Export Citation Format

Share Document