Three-Dimensional Fluid Dynamics in a Two-Dimensional Amount of Central Memory

1987 ◽  
pp. 85-146 ◽  
Author(s):  
Steven Greenberg ◽  
David M. McQueen ◽  
Charles S. Peskin
Keyword(s):  
Fluid Dynamics ◽  
Three Dimensional ◽  
Central Memory ◽  
Two Dimensional

The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

2013 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Velocity ◽  
Lower Velocity ◽  
Cfd Models ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

Direct Design of Ducts

2003 ◽  
Vol 125 (1) ◽  
pp. 158-165 ◽  
Author(s):  
A. Ashrafizadeh ◽  
G. D. Raithby ◽  
G. D. Stubley
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Distribution ◽  
Design Method ◽  
Three Dimensional ◽  
Viscous Flows ◽  
Simple Extension ◽  
Two Dimensional ◽  
Direct Design ◽  
Dependent Variables

This paper describes a method for calculating the shape of duct that leads to a prescribed pressure distribution on the duct walls. The proposed design method is computationally inexpensive, robust, and a simple extension of existing computational fluid dynamics methods; it permits the duct shape to be directly calculated by including the coordinates that define the shape of the duct wall as dependent variables in the formulation. This “direct design method” is presented by application to two-dimensional ideal flow in ducts. The same method applies to many problems in thermofluids, including the design of boundary shapes for three-dimensional internal and external viscous flows.

Impact of Cavity on Sunroof Buffeting: A Two Dimensional CFD Study

2004 ◽  
Author(s):  
Chang-Fa An ◽  
Seyed Mehdi Alaie ◽  
Michael S. Scislowicz
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Three Dimensional ◽  
Leading Edge ◽  
Two Dimensional ◽  
Deep Insight ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
The Impact ◽  
Insight Into

Driven by fluid dynamics principles, the concept for buffeting reduction, a cavity installed at the leading edge of the sunroof opening, is analyzed. The cavity provides a room to hold the vortex, shed from upstream, and prevents the vortex from escaping and from directly intruding into the cabin. The concept has been verified by means of a two dimensional simulation for a production SUV using the CFD software — FLUENT. The simulation results show that the impact of the cavity is crucial to reduce buffeting. It is shown that the buffeting level may be reduced by 3 dB by adding a cavity to the sunroof configuration. Therefore, the cavity could be considered as a means of buffeting reduction, in addition to the three currently-known concepts: wind deflector, sunroof glass comfort position and cabin venting. Thorough understanding of the buffeting mechanism helps explain why and how the cavity works to reduce buffeting. Investigation of the buffeting-related physics provides a deep insight into the flow nature and, therefore, a useful hint to geometry modification for buffeting reduction. The buffeting level may be further reduced by about 4 dB or more by cutting the corners of the sunroof opening into smooth ramps, guided by ideas coming from careful examining the physics of flow. More work including three dimensional simulation and wind tunnel experiment should follow in order to develop more confidence in the functionality of the cavity to hopefully promote this idea to the level that it can be utilized in a feasible way to address sunroof buffeting.

Variable pitch control for vertical-axis wind turbines

2018 ◽  
Vol 42 (2) ◽  
pp. 128-135 ◽  
Author(s):  
S Horb ◽  
R Fuchs ◽  
A Immas ◽  
F Silvert ◽  
P Deglaire
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Variable Pitch ◽  
Pitch Control

NENUPHAR aims at developing the next generation of large-scale floating offshore vertical-axis wind turbine. To challenge the horizontal-axis wind turbine, the variable blade pitch control appears to be a promising solution. This article focuses on blade pitch law optimization and resulting power and thrust gain depending on the operational conditions. The aerodynamics resulting from the implementation of a variable blade pitch control are studied through numerical simulations, either with a three-dimensional vortex code or with two-dimensional Navier-stokes simulations (two-dimensional computational fluid dynamics). Results showed that the three-dimensional vortex code used as quasi-two-dimensional succeeded to give aerodynamic loads in very good agreement with two-dimensional computational fluid dynamics simulation results. The three-dimensional-vortex code was then used in three-dimensional configuration, highlighting that the variable pitch can enhance the vertical-axis wind turbine power coefficient ( Cp) by more than 15% in maximum power point tracking mode and decrease it by more than 75% in power limitation mode while keeping the thrust below its rated value.

Modeling of an Integrated Wind Energy Building

2007 ◽  
Author(s):  
William E. Pedersen ◽  
Daniel N. Pope
Keyword(s):  
Fluid Dynamics ◽  
Numerical Modeling ◽  
Wind Energy ◽  
Three Dimensional ◽  
Building Structure ◽  
Two Dimensional ◽  
Free Standing ◽  
Pressure Area ◽  
Computational Fluid Dynamics Cfd ◽  
Geographic Regions

This study presents the design and modeling of an integrated wind energy building. It is proposed that a building be constructed with an integral wind turbine that takes advantage of the funneling of wind from the building structure and the low pressure area above or leeward of the building. Computational Fluid Dynamics (CFD) was used to evaluate different building geometries and wind potentials. Preliminary investigations using two dimensional numerical modeling in both the horizontal and vertical planes are presented. Three dimensional analyses are also presented of promising geometries from the two dimensional preliminary results. While additional modeling efforts will be necessary to optimize this system, results indicate a significant improvement in performance over free standing turbines, allowing for utilization of wind power in geographic regions that have traditionally not been feasible.

The application of computational fluid dynamics to natural river channels: three-dimensional versus two-dimensional approaches

Geomorphology ◽  
1999 ◽  
Vol 29 (1-2) ◽  
pp. 1-20 ◽  
Author(s):  
S.N. Lane ◽  
K.F. Bradbrook ◽  
K.S. Richards ◽  
P.A. Biron ◽  
A.G. Roy
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Two Dimensional ◽  
River Channels

Development of a Two-Dimensional Computational Fluid Dynamics Approach for Computing Three-Dimensional Honeycomb Labyrinth Leakage

2004 ◽  
Vol 126 (4) ◽  
pp. 794-802 ◽  
Author(s):  
Dong-Chun Choi ◽  
David L. Rhode
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Cfd Model ◽  
Resource Requirement ◽  
Three Dimensional Flow ◽  
Dimensional Flow

A new approach for employing a two-dimensional computational fluid dynamics (CFD) model to approximately compute a three-dimensional flow field such as that in a honeycomb labyrinth seal was developed. The advantage of this approach is that it greatly reduces the computer resource requirement needed to obtain a solution of the leakage for the three-dimensional flow through a honeycomb labyrinth. After the leakage through the stepped labyrinth seal was measured, it was used in numerically determining the value of one dimension (DTF1) of the simplified geometry two-dimensional approximate CFD model. Then the capability of the two-dimensional model approach was demonstrated by using it to compute the three-dimensional flow that had been measured at different operating conditions, and in some cases different distance to contact values. It was found that very close agreement with measurements was obtained in all cases, except for that of intermediate clearance and distance to contact for two sets of upstream and downstream pressure. The two-dimensional approach developed here offers interesting benefits relative to conventional algebraic-equation models, particularly for evaluating labyrinth geometries/operating conditions that are different from that of the data employed in developing the algebraic model.

The Effect of Time-Varying Wind Direction on the Indoor Climate of a Naturally Ventilated Greenhouse

2010 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Wind Direction ◽  
Three Dimensional ◽  
Time Varying ◽  
Two Dimensional ◽  
Indoor Climate ◽  
Transient Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level ◽  
Transient Wind

This paper presents a numerical investigation into the indoor climate of a four span naturally ventilated, four span greenhouse subject to a time-varying wind direction. The effect of transient wind conditions on the temperature and velocity distribution inside the greenhouse is numerically determined using Computational Fluid Dynamics (CFD). The research in this paper is an extension of work previously conducted on two-dimensional models of greenhouses. Current work concentrates on the three-dimensional effect of external winds. Results indicate that for a wind direction of 22.5 degrees, the microclimate at plant level varies throughout the length of the greenhouse. It was also found from transient simulations that even a slight change in wind direction have a pronounced effect on the indoor climate at plant level.

A Computational Fluid Dynamics Comparison of Wells Turbine Blades in 2D and 3D Cascade Flow

2002 ◽  
Author(s):  
John Daly ◽  
Patrick Frawley ◽  
Ajit Thakker
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Primary Objective ◽  
Two Dimensional ◽  
Three Dimensional Model ◽  
Wells Turbine ◽  
Cascade Flow ◽  
Cascade Models

This paper deals with the application of Computational Fluid Dynamics (CFD) to the analysis of the aerodynamic characteristics of symmetrical airfoil blades in 2-Dimensional cascade flow. Theoretical two dimensional cascade analyses of Wells Turbines blade profiles have been used in the past to predict the performance of three-dimensional turbines. The use of two-dimensional cascade models is beneficial as it allows the analysis and optimisation of the blade profile with approximately one tenth the computational requirements of a three-dimensional model. The primary objective of this work was to provide further validation of the use of two dimensional cascade models by comparing the computational predictions with traditional theoretical calculation results and also with three-dimensional turbine results. A secondary objective was to use the two dimensional cascade models to better understand the blade interaction effects that occur in the Wells Turbine. The model was used to analyse and compare three different blade profiles at different cascade settings. This paper presents the results of the numerical investigation, the validation of the results and the subsequent analysis.

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