A Three-Dimensional Computational Fluid Dynamics (CFD) Model Analysis of Free Surface Hydrodynamics and Fish Passage Energetics in a Vertical-Slot Fishway

2006 ◽  
Vol 26 (2) ◽  
pp. 255-267 ◽  
Author(s):  
Liaqat A. Khan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Free Surface ◽  
Three Dimensional ◽  
Fish Passage ◽  
Model Analysis ◽  
Cfd Model ◽  
Vertical Slot ◽  
Computational Fluid Dynamics Cfd ◽  
Vertical Slot Fishway

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.

Numerical Simulation of the Fixed Barge Barge Interaction Under Irregular Wave Using HOS-StarCCM+ Coupling Tool With Experiment Validation

2021 ◽  
Author(s):  
Yali Zhang ◽  
Haihua Xu ◽  
Harrif Santo ◽  
Kie Hian Chua ◽  
Yun Zhi Law ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Free Surface ◽  
Potential Flow ◽  
Computational Domain ◽  
Cfd Model ◽  
Flow Models ◽  
Irregular Wave ◽  
Computational Fluid Dynamics Cfd ◽  
Wave Conditions

Abstract The interaction between two side-by-side floating vessels has been a subject of interest in recent years due floating liquefied natural gas (FLNG) developments. The safety and operability of these facilities are affected by the free-surface elevation in the narrow gap between the two vessels as well as the relative motions between the vessels. It is common practice in the industry to use potential flow models to estimate the free-surface responses in the gap under various wave conditions. However, it is well-known that any potential flow models require calibration of viscous damping, and model tests are carried out to provide a platform to calibrate the potential flow models. To improve beyond the potential flow models, Computational Fluid Dynamics (CFD) models will be required. However, the large computational efforts required render the conventional CFD approaches impractical for simulations of wave-structure interactions over a long duration. In this paper, a developed coupled solver between potential flow and Computational Fluid Dynamics (CFD) model is presented. The potential flow model is based on High-Order Spectral method (HOS), while the CFD model is based on fully nonlinear, viscous and two phase StarCCM+ solver. The coupling is achieved using a forcing zone to blend the outputs from the HOS into the StarCCM+ solver. Thus, the efficient nonlinear long time simulation of arbitrary input wave spectrum by HOS can be transferred to the CFD domain, which can reduce the computational domain and simulation time. In this paper, we make reference to the model experiments conducted by Chua et al. (2018), which consist of two identical side-by-side barges of 280 m (length) × 46 m (breadth) × 16.5 m (draught) tested in regular and irregular wave conditions. Our intention is to numerically reproduce the irregular wave conditions and the resulting barge-barge interactions. We first simulate the actual irregular wave conditions based on wave elevations measured by the wave probes using the HOS solver. The outputs are subsequently transferred to the CFD solver through a forcing zone in a 2D computational domain for comparison of the irregular wave conditions without the barges present. Subsequently, a 3D computational domain is set up in the CFD with fixed side-by-side barges modelled, and the interaction under irregular waves is simulated and compared with the experiments. We will demonstrate the applicability of the HOS-StarCCM+ coupling tool in terms of accuracy, efficiency as well as verification and validation of the results.

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.

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.

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.

A Computational Fluid Dynamics (CFD) Study of Material Transport and Deposition in Aerosol Jet Printing (AJP) Process

2018 ◽  
Author(s):  
Roozbeh (Ross) Salary ◽  
Jack P. Lombardi ◽  
Darshana L. Weerawarne ◽  
Prahalada K. Rao ◽  
Mark D. Poliks
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Flow ◽  
Complex Geometry ◽  
Sensor Data ◽  
Cfd Model ◽  
Material Transport ◽  
Jet Printing ◽  
Computational Fluid Dynamics Cfd ◽  
Aerosol Jet Printing

The objective of this work is to forward a 3D computational fluid dynamics (CFD) model to explain the aerodynamics behind aerosol transport and deposition in aerosol jet printing (AJP). The CFD model allows for: (i) mapping of velocity fields as well as particle trajectories; and (ii) investigation of post-deposition phenomena of sticking, rebounding, spreading, and splashing. The complex geometry of the deposition head was modeled in the ANSYS-Fluent environment, based on a patented design as well as accurate measurements, obtained from 3D X-ray CT imaging. The entire volume of the geometry was subsequently meshed, using a mixture of smooth and soft quadrilateral elements, with consideration of layers of inflation to obtain an accurate solution near the walls. A combined approach — based on the density-based and pressure-based Navier-Stokes formation — was adopted to obtain steady-state solutions and to bring the conservation imbalances below a specified linearization tolerance (10−6). Turbulence was modeled, using the realizable k-ε viscose model with scalable wall functions. A coupled two-phase flow model was set up to track a large number of injected particles. The boundary conditions were defined based on experimental sensor data. A single-factor factorial experiment was conducted to investigate the influence of sheath gas flow rate (ShGFR) on line morphology, and also validate the CFD model.

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