Flowfield Uncertainty Analysis for Hypersonic CFD Simulations

Uncertainty quantification (UQ) in the hypersonic flow regime offers valuable information to determine physical models in need of improvement and to assist in design of vehicles and flight experiments. Here we present results of UQ analysis based on polynomial chaos method to determine flowfield and surface heat flux uncertainty under typical blunt-body re-entry conditions. The NASA Langley code, LAURA, was used for axisymmetric CFD calculations of chemically reacting hypersonic flow over FIRE-II configuration. A third order polynomial chaos (PC) method using the Gauss-Hermite quadrature was applied for determining probability density functions and moments of output quantities. Input parameters such as freestream density, velocity, and temperature were varied and the propagation of their corresponding uncertainties on output properties of interest through the flowfield were studied. An order of magnitude increase in surface heat flux uncertainties was observed for an input freestream velocity uncertainty of ±100 ft/s, or 0.29%. This parameter thus has the greatest sensitivity to variations, and conversely the freestream temperature has the least sensitivity

No Student is an Island—Students’ Perspectives of Sense of Community in Online Higher Education

The Australian Department of Education and Training statistics show that more students than ever are enrolling in online study (Australian Government Department of Education, 2019), a trend that is mirrored abroad (Grinder, Kelly-Reid, & Mann, 2019). Research also show that the majority of Australian students enrolled in online programs are mature-age students (Norton, Cherastidtham, & Mackey, 2018). The increased popularity of online programs, especially for mature-age students, likely reflects the need for students to fit their study around the competing demands of work and family life. Whilst online courses offer students increased flexibility, they also present a challenge when it comes to building a sense of community. Higher education research shows that sense of belonging and community in higher education is positively associated with academic performance, self-confidence, engagement, retention, and satisfaction with the university experience (Freeman, Anderman, & Jensen, 2007; Chang & Smith, 2008; Hausmann, Schofield, & Woods, 2007; LaPointe & Gunawardena, 2004; Liu, Magjuka, Bonk, & Lee, 2007; Ouzts, 2006; Rovai, Wighting, & Liu, 2005; Strayhorn, 2012; Swan, 2002; Thomas, Herbert, & Teras, 2014). Conversely, feelings of isolation and alienation among online learners contribute to learner dissatisfaction and attrition (Rovai, 2001; Schaeffer & Konetes, 2010). This chapter will describe the challenges faced when building a sense of community for fully online students and outline strategies to address the unique challenges faced in a fully online program