Numerical study of separated boundary layer transition under pressure gradient

Large-eddy simulation (LES) is conducted to study the transition process of a separated boundary layer on a flat plate with an elliptical leading edge. A streamwise pressure distribution is imposed and the free stream turbulence intensity is 3% to mimic the suction surface of a low-pressure turbine (LPT) blade. A dynamic sub-grid scale model is employed in the study and the current LES results compare well with available experimental data and previous LES results. The transition process has been analysed with a particular focus on primary instabilities at work. Streaky structures further upstream of the separation, known as the Klebanoff Streaks, have been observed. Typical two-dimensional Kelvin-Helmholtz (K-H) rolls are distorted in the separated region. When Klebanoff streaks passing over a full-span K-H roll, portion of the two-dimensional roll merges with the Klebanoff streaks and develop into chaotic three-dimensional structures, whereas the remaining undisrupted two-dimensional K-H rolls develop into Λ-vortex indicating that despite the disturbances before separation, the K-H instability may still be the main instability at work

Promoting Eco-driving through Persuasive Visualization

The goal of sustainability is to preserve resources for future generations. Climate change is a major environmental problem that violates the goal of sustainability. A key strategy to combat climate change is to reduce carbon emission that is largely generated by road transport. Traditional interventions on promoting eco-driving behaviors often fail to convince people to alter their driving behaviors. The growing use of persuasive visualization allows individuals to become aware of the relationship between their driving behaviors and the associated environmental impact. Drawing on the expectancy theory of motivation, this study plans to explore ways to design effective visualization to promote eco-driving behaviors. Additionally, this study proposes a unique lab experiment that enables the manipulation of visualizations and presents an opportunity to observe individuals’ driving behavioral changes

Promoting Driving Safety with Self-Evaluation Maintenance: Human-Human and Human-Artificial Intelligence Performance Comparisons

In this study, we develop and test a model that explains individuals’ behavioral changes in driving safety after viewing the visualizations, which depict their driving performance against that of artificial intelligence (AI). This study draws on the self-evaluation literature to understand performance comparisons and extends the self-evaluation perspective to the context of human-AI comparisons. Furthermore, this study illustrates that individuals can be incited emotionally by performance comparisons, and these emotional responses influence their driving behaviors subsequently. The results of this study generally support our model. Overall, this study sheds light on how competition between humans and computers can be utilized to promote desirable behaviors

Debunking Sustainability Excuses with Instrumentality and Expectancy Visualizations: A Physiological Perspective

This study advances the IS literature by investigating the effects of visualization on promoting sustainability knowledge and pro-environmental behaviors. Specifically, drawing on the visualization literature, we explain how the key visualization features, expectancy illustration, and interactivity affect individuals’ understanding of the impact of their behaviors on the environment, encouraging pro-environmental behaviors. Additionally, we draw on the pedagogy literature to explicate that the effects of visualization on learning outcomes and pro-environmental practices can be explained through individuals’ psychological responses in their course of interpreting the visualization. Collectively, this study presents our endeavor in understanding the roles of visualization in ecological discourse by integrating the visualization literature and sustainability research. Moreover, by unboxing individuals’ psychological processes in interpreting visualization, we offer a fresh perspective to understanding the promises and challenges of using visualization for knowledge acquisition

Unlocking Sustainability with Visualizations: Driving the Driven through the Whys and Hows

Visualizations have been broadly employed to help individuals understand complex environmental issues and encourage sustainable behaviors. However, sustainability knowledge only sometimes transpires to actual green practices. In this study, we explain the effects of post-trip visualized storytelling on eco-driving behaviors. We conducted a laboratory experiment involving eye-tracking and driving simulation. This study contributes to the literature by unraveling the impact of visualized narratives on behaviors and demonstrating eco-driving behaviors in multiple manifestations

Promoting Eco driving with Post Trip Visualized Storytelling

Visualized storytelling is often used to explain complicated environmental issues, raise ecological consciousness, and promote sustainable behavior. In this study, we develop and test a model demonstrating how post-trip visualized storytelling encourages eco driving behaviors. We explore the effect of post trip visualizations on eco driving behaviors by examining the literature on human-computer interaction. We test our hypothesis in an experiment using eye tracking and driving simulation. Results indicate that animated illustrations and narrative sequence improved eco driving practices. Overall, this study contributes to information systems literature by unraveling the effects of post-trip visualized storytelling on eco driving behaviors

Design, fabrication and performance evaluation of a compact regenerative evaporative cooler: towards low energy cooling for buildings

© 2017 Elsevier Ltd The urges of reducing energy use and carbon footprint in buildings have prompted the developments of regenerative evaporative coolers (RECs). However, the physical dimensions of RECs have to be designed enormous in order to deliver a large amount of supply airflow rate and cooling capacity. To tackle the issue, this paper develops a large-scale counter-flow REC with compact heat exchanger through dedicated numerical modelling, optimal design, fabrication and experimentation. Using modified ε-NTU method, a finite element model is established in Engineering Equation Solver environment to optimise the cooler's geometric and operating parameters. Based on modelling predictions, the cooler's experimental prototype was optimally designed and constructed to evaluate operating performance. The experiment results show that the cooler's attained wet-bulb effectiveness ranges from 0.96 to 1.07, the cooling capacity and energy efficiency ratio from 3.9 to 8.5 kW and 10.6 to 19.7 respectively. It can provide sub-wet bulb cooling while operating at high intake channel air velocities of 3.04–3.60 m/s. The superior performance of proposed cooler is disclosed by comparing with different RECs under similar operating conditions. Both the cooler's cooling capacity per unit of volume and per unit of airflow rate are found to be 62–108% and 21.6% higher respectively

Social Comparisons in Social Exercise Apps

A key strategy to combat sedentary lifestyle is to encourage fitness exercises. Traditional wellness and lifestyle management programs focus on inducing health awareness and providing fitness activity support. The growing pervasive use of smartphones allows individualized and cost-effective digital wellness programs to be administrated through mobile fitness apps. Drawing on the social comparison theory, this study plans to explore ways to effectively design social comparison mechanisms to help promote physical exercises. Additionally, this study proposes a unique field experiment that enables fine- grained manipulation of social comparisons and present an opportunity to observe network evolutions over time

Numerical study of separated boundary layer transition under pressure gradient

Large-eddy simulation (LES) is conducted to study the transition process of a separated boundary layer on a flat plate with an elliptical leading edge. A streamwise pressure distribution is imposed and the free stream turbulence intensity is 3% to mimic the suction surface of a low-pressure turbine (LPT) blade. A dynamic sub-grid scale model is employed in the study and the current LES results compare well with available experimental data and previous LES results. The transition process has been analysed with a particular focus on primary instabilities at work. Streaky structures further upstream of the separation, known as the Klebanoff Streaks, have been observed. Typical two-dimensional Kelvin-Helmholtz (K-H) rolls are distorted in the separated region. When Klebanoff streaks passing over a full-span K-H roll, portion of the two-dimensional roll merges with the Klebanoff streaks and develop into chaotic three-dimensional structures, whereas the remaining undisrupted two-dimensional K-H rolls develop into Λ-vortex indicating that despite the disturbances before separation, the K-H instability may still be the main instability at work.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016