Closure to “Discussion of ‘Effects of Wall Shape on Flow Regimes and Performance in Straight, Two-Dimensional Diffusers’” (1967, ASME J. Basic Eng., 89, pp. 159–160)

1967 ◽  
Vol 89 (1) ◽  
pp. 160-160
Author(s):  
J. J. Carlson ◽  
J. P. Johnston ◽  
C. J. Sagi
Keyword(s):  
Flow Regimes ◽  
Two Dimensional ◽  
And Performance

Effects of Wall Shape on Flow Regimes and Performance in Straight, Two-Dimensional Diffusers

1967 ◽  
Vol 89 (1) ◽  
pp. 151-159 ◽  
Author(s):  
J. J. Carlson ◽  
J. P. Johnston ◽  
C. J. Sagi
Keyword(s):  
Flow Regime ◽  
Performance Prediction ◽  
Prediction Method ◽  
Flow Regimes ◽  
Two Dimensional ◽  
Simple Class ◽  
And Performance

Three diffuser sets (N/W1, held constant in each set) were built and tested for performance and flow regime over a range of total area ratios, AR, which yielded unstalled and stalled flows. At each AR and N/W1, a simple class of convex-inward (trumpet-shaped), straight, and convex-outward (bell-shaped) wall shapes were tested. It is concluded that there is little advantage to be gained by contouring the walls of two-dimensional diffusers. A corollary result shows that the performance prediction method of reference [1] gives good results for unstalled diffusers.

Effects of Nonuniform Inlet Velocity Profiles on Flow Regimes and Performance in Two-Dimensional Diffusers

1969 ◽  
Vol 91 (3) ◽  
pp. 462-474 ◽  
Author(s):  
S. Wolf ◽  
J. P. Johnston
Keyword(s):  
Shear Flows ◽  
Prediction Method ◽  
Flow Regimes ◽  
Velocity Profiles ◽  
Two Dimensional ◽  
Rotational Model ◽  
Inlet Velocity ◽  
The Core ◽  
Uniform Shear ◽  
And Performance

An analytical and experimental study on the effects of large distortions of inlet velocity profiles on flow regimes and performance in diffusers is reported. Experiments are restricted to flow in straight, two-dimensional diffusers with turbulent boundary layers. Systematic data are obtained for two general types of inlet flows: (1) simple, uniform shear flows in the core, and (2) severely nonuniform shear flows of the wake, jet, and step-shear type. For uniform shear flows a first order prediction method based on inviscid rotational flow and the boundary layer blockage concept is developed and verified for diffusers operating in the unstalled flow regime. For nonuniform shear flows the inviscid rotational model is shown to predict performance trends better than the irrotational model; however, the inviscid rotational model is inadequate as a precise prediction method because no account is taken of mixing in the core region. Geometry and performance correlations for peak pressure recovery (at constant N/W1) are also established.

scholarly journals CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Fabio Nardecchia ◽  
Annalisa Di Bernardino ◽  
Francesca Pagliaro ◽  
Paolo Monti ◽  
Giovanni Leuzzi ◽  
...  
Keyword(s):  
Flow Field ◽  
Water Channel ◽  
Flow Regimes ◽  
Two Dimensional ◽  
Mean Flow ◽  
Ansys Fluent ◽  
Practical Applications ◽  
Aspect Ratios ◽  
Starting Point ◽  
Step Down

Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. The starting point of this work is the performance assessment of the V2F (i.e., v2¯ − f) model implemented in Ansys Fluent for simulating the flow field in an idealized array of two-dimensional canyons. The V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. The numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-ε and k-ω models and the Reynolds stress model). The results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. The V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. The results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.

Reality and Diversity: Reform in the Architectural Design Studio

2006 ◽  
Vol 31 (2) ◽  
pp. 20-31
Author(s):  
Jia Beisi
Keyword(s):  
Learning Styles ◽  
Learning Style ◽  
Personal Experience ◽  
Architectural Design ◽  
Learning Activities ◽  
Two Dimensional ◽  
Learning Style Inventory ◽  
Reflection In Action ◽  
Architectural Design Studio ◽  
And Performance

Habraken points out that the architectural studio failed to bring students to basic questions in the architecture of everyday environments. Till criticizes that in a studio, it is only the professional value represented by the teachers that prevails. To investigate the reasons of the allegation, this paper introduces a learning model defined by David A. Kolb, in which a learning process consists of two dimensional movements: i.e., prehension (concrete experiences vs. abstract conceptualization) and transformation (reflection and experiment). The paper then inquires into Schön's observation in the studio learning mode characterized as reflection-in-action. It is found that this studio is mainly dealing with the transformation dimension, and prehension dimension is either suppressed or represented by the teacher's experiences and conceptions. The paper discovers that the cause of problems raised by Habraken and Till is the inherent lack of substance in the prehension dimension. The paper assesses a studio programme in which the basic questions of built environment were systematically introduced. It analyzes the students' reactions and performance in line with students' learning styles found using Kolb's Learning Style Inventory (LSI). It suggests that the students' learning activities are more diversified than what Schön could perceive. There is a possibility to adapt students' personal experience and abstract conceptualization which may play into the studio. By enhancing diversity of learning styles rather than letting one's learning style (reflection-in-action) prevail, the studio may become a platform in which students may learn from each other.

Mycielski Based 2d-Predictive Image Coding Algorithm

2016 ◽  
Vol 850 ◽  
pp. 144-151 ◽  
Author(s):  
Mehmet Fidan ◽  
Ömer Nezih Gerek
Keyword(s):  
Image Coding ◽  
Predictive Coding ◽  
Prediction Method ◽  
Physical Distance ◽  
Prediction Algorithm ◽  
Two Dimensional ◽  
Two Dimensional Image ◽  
Past Data ◽  
And Performance ◽  
Definition Of

The Mycielski method is a prospering prediction algorithm which is based on searching and finding largest repeated binary patterns. It uses infinite-past data to devise a rule based prediction method on a time series. In this work, a novel two-dimensional (image processing) version of the Mycielski algorithm is proposed. Since the dimensionality definition of “past” data increases in two-dimensional signals, the proposed algorithm also needs to handle how the boundaries of the pixel cliques are iteratively extended in the neighborhood of a current pixel. The clique extension invokes novel similarity search strategies that depend on the chosen physical distance metric. The proposed prediction algorithm is used for predictive image compression and performance comparisons with other predictive coding methods are presented.

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