Selection of a computational fluid dynamics (CFD) model and its application to greenhouse pad-fan cooling (PFC) systems

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.

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

Volume 2: CFD and VIV ◽

10.1115/omae2014-23136 ◽

2014 ◽

Cited By ~ 1

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.

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A Study on Selection of the Biofilm for the Hybrid Up-Flow Anaerobic Sludge Blanket (HUASB) Reactor Using the Computational Fluid Dynamics (CFD) Analysis

Emerging Technologies for Waste Valorization and Environmental Protection ◽

10.1007/978-981-15-5736-1_3 ◽

2020 ◽

pp. 19-27

Author(s):

R. Loganath ◽

J. Senophiyah-Mary ◽

Teema Thomas

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Anaerobic Sludge ◽

Cfd Analysis ◽

Computational Fluid Dynamics Cfd ◽

Anaerobic Sludge Blanket ◽

Selection Of

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Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽

10.3390/fluids3040073 ◽

2018 ◽

Vol 3 (4) ◽

pp. 73 ◽

Cited By ~ 10

Author(s):

Galih Bangga

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Flow Separation ◽

Spatial Interpolation ◽

Flow Conditions ◽

Cfd Simulations ◽

Computational Fluid Dynamics Cfd ◽

Correction Terms ◽

Selection Of ◽

Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

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

Water Practice & Technology ◽

10.2166/wpt.2009.015 ◽

2009 ◽

Vol 4 (1) ◽

Cited By ~ 2

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.

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

Volume 2: Advanced Manufacturing ◽

10.1115/imece2018-87647 ◽

2018 ◽

Cited By ~ 1

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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Verification and Validation of a Detonation Computational Fluid Dynamics Model

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.366.40 ◽

2016 ◽

Vol 366 ◽

pp. 40-46

Author(s):

Rui Li Wang ◽

Xiao Liang ◽

Wen Zhou Lin ◽

Xue Zhe Liu ◽

Yun Long Yu

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Cfd Simulation ◽

Verification And Validation ◽

Cfd Model ◽

Dynamics Model ◽

Computational Fluid Dynamics Model ◽

Primary Means ◽

Computational Fluid Dynamics Cfd ◽

2D Space

Verification and validation (V&V) are the primary means to assess the accuracy and reliability in computational fluid dynamics (CFD) simulation. V&V of the multi-medium detonation CFD model is conducted by using our independently-developed software --- Lagrangian adaptive hydrodynamics code in the 2D space (LAD2D) as well as a large number of benchmark testing models. Specifically, the verification of computational model is based on the basic theory of the computational scheme and mathematical physics equations, and validation of the physical model is accomplished by comparing the numerical solution with the experimental data. Finally, some suggestions are given about V&V of the detonation CFD model.

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