scholarly journals The reduced order NS-αmodel for incompressible flow: theory, numerical analysis and benchmark testing

2015 ◽  
Vol 49 (3) ◽  
pp. 641-662 ◽  
Author(s):  
Victoria M. Cuff ◽  
Argus A. Dunca ◽  
Carolina C. Manica ◽  
Leo G. Rebholz
Fluids ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 50 ◽  
Author(s):  
Sk. Rahman ◽  
Adil Rasheed ◽  
Omer San

Numerical solution of the incompressible Navier–Stokes equations poses a significant computational challenge due to the solenoidal velocity field constraint. In most computational modeling frameworks, this divergence-free constraint requires the solution of a Poisson equation at every step of the underlying time integration algorithm, which constitutes the major component of the computational expense. In this study, we propose a hybrid analytics procedure combining a data-driven approach with a physics-based simulation technique to accelerate the computation of incompressible flows. In our approach, proper orthogonal basis functions are generated to be used in solving the Poisson equation in a reduced order space. Since the time integration of the advection–diffusion equation part of the physics-based model is computationally inexpensive in a typical incompressible flow solver, it is retained in the full order space to represent the dynamics more accurately. Encoder and decoder interface conditions are provided by incorporating the elliptic constraint along with the data exchange between the full order and reduced order spaces. We investigate the feasibility of the proposed method by solving the Taylor–Green vortex decaying problem, and it is found that a remarkable speed-up can be achieved while retaining a similar accuracy with respect to the full order model.


Target ◽  
2011 ◽  
Vol 23 (2) ◽  
pp. 251-271 ◽  
Author(s):  
Mehdi Mirlohi ◽  
Joy Egbert ◽  
Behzad Ghonsooly

The study reported here examined the amount and quality of flow experienced by trainee translators while translating different text genres. Flow (Csikszentmihalyi 1975) is an optimal experience, characterized by intense focus, control, interest and skills-challenge balance that leads to enhanced performance on a task. Although investigated in areas such as professional sports, surgery, and music, Flow Theory has not yet been tested in the area of translation. This study aimed at identifying which discourse genre would induce most flow in trainee translators while translating. Fifty-six Iranian English Translation majors studying at the University of Kashan translated three 180-word texts of narrative, expository, and descriptive genres. After each translation, they responded to a Flow Perceptions Questionnaire (Egbert, 2003) in the Likert format to report their perceptions of flow. Using repeated measures ANOVA, the researchers investigated flow differences among genres. The results indicated that flow existed in the translation classroom and that there were significant differences in the flow scores engendered by different genres. To support the findings drawn from the numerical analysis, four participants, selected from the population of subjects from the first phase, were interviewed, and the analysis of the interviews generally corroborated the statistical findings.


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