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The world is constantly changing, and the practice of engineering, therefore, requires that professionals and students continuously learn and critically think to persist in solving complex societal problems. For students, this requirement calls for an ability to use appropriate strategies to acquire and apply new knowledge as needed. However, undergraduate engineering curricula rarely directly develop students’ ability to reflect - assess their skill/knowledge gaps and plan for their learning. In civil engineering core coursework, the use of theory-grounded reflection exercises that emphasize metacognitive regulation strategies (MRSs) may aid instructors in developing students’ reflexivity and ability to be self-directed learners. The purpose of this single-case design research study was to examine a student’s progression in their application of MRSs while engaged in structured reflections in four core courses in their civil engineering program. Data were collected between Fall 2023 and Fall 2025 at an R1 Midwestern US university. The participant used reflections to identify a difficulty encountered while completing an assignment, assess actions taken, and plan further actions to improve learning. Qualitative methods were used to analyze the participant's reflections for the use of MRSs. Results showed that the participant demonstrated increased ability to engage in multiple elements of MRSs. By increasing student’s abilities with MRSs, critical thinking skills may be improved and that will be useful for solving new and unfamiliar problems in the future. 

Developing students’ metacognitive regulation and effective use of learning strategies is central to supporting adaptive learning in engineering education. This qualitative single-case study examined one undergraduate engineering student’s metacognitive regulation and use of learning strategies across four semesters that incorporated structured written reflection. The student’s 19 reflections were deductively coded at the element level of the three metacognitive regulation dimensions: Monitoring, Evaluating, and Planning. The students’ texts for each element were classified for level of detail (None, Vague, or Sufficiently Detailed), and each dimension assigned an overall proficiency level. In parallel, the student’s knowledge and use of learning strategies, as communicated through their reflections and pre-post surveys, were analyzed. Results indicated overall movement from Emerging toward Developing and, in some cases, Proficient engagement across the three dimensions, though growth was uneven across semesters. Improvements were most evident in elements that required concrete descriptions, while elements requiring abstract thinking remained more inconsistently articulated. The student’s level of detail was lowest for Planning. Across semesters, growth in knowledge of learning strategies reflected increased frequency of Consolidating-Surface and Acquiring-Deep strategies. These findings suggest that sustained instructional support plays a critical role in developing metacognitive regulation. Instructors should continue supporting students with clear feedback and instructions from the reflection activities, especially for elements that require sensemaking. 

Symmetry-based analyses of multiscale velocity gradients highlight that strain self-amplification (SS) and vortex stretching (VS) drive forward energy transfer in turbulent flows. By contrast, a strain–vorticity covariance mechanism produces backscatter that contributes to the bottleneck effect in the subinertial range of the energy cascade. We extend these analyses by using a normality-based decomposition of filtered velocity gradients in forced isotropic turbulence to distinguish contributions from normal straining, pure shearing and rigid rotation at a given scale. Our analysis of direct numerical simulation (DNS) data illuminates the importance of shear layers in the inertial range and (especially) the subinertial range of the cascade. Shear layers contribute significantly to SS and VS and play a dominant role in the backscatter mechanism responsible for the bottleneck effect. Our concurrent analysis of large-eddy simulation (LES) data characterizes how different closure models affect the flow structure and energy transfer throughout the resolved scales. We thoroughly demonstrate that the multiscale flow features produced by a mixed model closely resemble those in a filtered DNS, whereas the features produced by an eddy viscosity model resemble those in an unfiltered DNS at a lower Reynolds number. This analysis helps explain how small-scale shear layers, whose imprint is mitigated upon filtering, amplify the artificial bottleneck effect produced by the eddy viscosity model in the inertial range of the cascade. Altogether, the present results provide a refined interpretation of the flow structures and mechanisms underlying the energy cascade and insight for designing and evaluating LES closure models. 

Turbulent boundary layers on immersed objects can be significantly altered by the pressure gradients imposed by the flow outside the boundary layer. The interaction of turbulence and pressure gradients can lead to complex phenomena such as relaminarization, history effects and flow separation. The angular momentum integral (AMI) equation (Elnahhas & Johnson,J. Fluid Mech., vol. 940, 2022, A36) is extended and applied to high-fidelity simulation datasets of non-zero pressure gradient turbulent boundary layers. The AMI equation provides an exact mathematical equation for quantifying how turbulence, free-stream pressure gradients and other effects alter the skin friction coefficient relative to a baseline laminar boundary layer solution. The datasets explored include flat-plate boundary layers with nearly constant adverse pressure gradients, a boundary layer over the suction surface of a two-dimensional NACA 4412 airfoil and flow over a two-dimensional Gaussian bump. Application of the AMI equation to these datasets maps out the similarities and differences in how boundary layers interact with favourable and adverse pressure gradients in various scenarios. Further, the fractional contribution of the pressure gradient to skin friction attenuation in adverse-pressure-gradient boundary layers appears in the AMI equation as a new Clauser-like parameter with some advantages for understanding similarities and differences related to upstream history effects. The results highlight the applicability of the integral-based analysis to provide quantitative, interpretable assessments of complex boundary layer physics. 

In Navier-Stokes turbulence, a bottleneck effect in the energy cascade near the viscous cutoff causes an overshoot in the energy spectrum, or spectral bump, relative to Komogorov’s−5/3 power-law scaling. A similar spectral overshoot occurs in large-eddy simulations (LES) when an eddy viscosity model is used. It is not a viscous phenomenon, but rather is caused by error in the residual stress model. This artificial bottleneck effect in LES leads to an over-prediction of kinetic energy even if a reliable dynamic procedure is used to accurately capture the spectral decay at the cutoff length scale. Recently, Johnson [J. Fluid Mech. 934, A30 (2022)] introduced a physics-inspired generalization of the concept of spatial filtering that provides a dynamic procedure that does not require a test filter calculation. In this paper, this method of Stokes flow regularization (SFR) is used alongside fundamental considerations related to kinetic energy to generate a range of LES models to explore the artificial bottleneck effect in more detail. The coefficients for each dynamic model are determined locally, without the need of averaging over homogeneous directions. The theory directly provides stabilizing elements such as local averaging of coefficients. A posteriori tests of the models in isotropic turbulence are reported, demonstrating the robustness of the SFR-based dynamic procedure for a range of model forms and providing a framework for fair comparisons between them in terms of their impact on the bottleneck effect. An effective means of mitigating the bottleneck effect is to introduce a nonlinear gradient component in the residual stress closure, forming a dynamic mixed model. One primary reason for the efficacy of this approach is that the nonlinear gradient model is able to accurately capture aspects of the local structure of the residual stresses, leading to a better representation of energy cascade efficiencies. 

New engineering educators need to be equipped with instruments that can provide easy and meaningful insight into students’ self-directed learning (SDL) status so they can better foster students’ success. Students who are self-directed learners can independently initiate and take full responsibility for learning, effectively utilize available resources in the pursuit of their goals, develop awareness of their learning, and demonstrate the appropriate attitude essential for individual and collaborative learning. Despite these benefits, developing SDL skills in engineering students is often overlooked. To address this, educators have a facilitating role to play in the development of engineering students’ SDL skills, however, this role can be challenging for them due to the (a) high cost of using SDL instruments, especially in a large classroom and (b) uncertainty about the validity of SDL instruments. Moreover, these challenges may be more pronounced for new engineering educators. This study addresses these challenges by reporting the validity evidence for an SDL assessment instrument called the Self-Rating Scale of Self-Directed Learning (SRSSDL). The SRSSDL instrument has been widely utilized in medical education, but in this study, it was modified for the engineering education context. The utility of this 8-constructs, 46-item scale was demonstrated in engineering education with 111 undergraduate students across all academic levels, and the validity test was conducted in line with the contemporary validity framework. The result of the validity test of the SRSSDL revealed inconsistencies or instability of its constructs in the engineering education context. 

Understanding and predicting turbulent flow phenomena remain a challenge for both theory and applications. The nonlinear and nonlocal character of small-scale turbulence can be comprehensively described in terms of the velocity gradients, which determine fundamental quantities like dissipation, enstrophy, and the small-scale topology of turbulence. The dynamical equation for the velocity gradient succinctly encapsulates the nonlinear physics of turbulence; it offers an intuitive description of a host of turbulence phenomena and enables establishing connections between turbulent dynamics, statistics, and flow structure. The consideration of filtered velocity gradients enriches this view to express the multiscale aspects of nonlinearity and flow structure in a formulation directly applicable to large-eddy simulations. Driven by theoretical advances together with growing computational and experimental capabilities, recent activities in this area have elucidated key aspects of turbulence physics and advanced modeling capabilities. 

Abstract Globally, glaciers are changing in response to climate warming, with those that terminate in water often undergoing the most rapid change. In Alaska and northwest Canada, proglacial lakes have grown in number and size but their influence on glacier mass loss is unclear. We characterized the rates of retreat and mass loss through frontal ablation of 55 lake-terminating glaciers (>14 000 km²⁾in the region using annual Landsat imagery from 1984 to 2021. We find a median retreat rate of 60 m a⁻¹(interquartile range = 35–89 m a⁻¹) over 1984–2018 and a median loss of 0.04 Gt a⁻¹(0.01–0.15 Gt a⁻¹) mass through frontal ablation over 2009–18. Summed over 2009–18, our study glaciers lost 6.1 Gt a⁻¹to frontal ablation. Analysis of bed profiles suggest that glaciers terminating in larger lakes and deeper water lose more mass to frontal ablation, and that the glaciers will remain lake-terminating for an average of 74 years (38–177 a). This work suggests that as more proglacial lakes form and as lakes become larger, enhanced frontal ablation could cause higher mass losses, which should be considered when projecting the future of lake-terminating glaciers.