120 research outputs found

    Stability of plane-Poiseuille flow interacting with a finite compliant panel

    Get PDF

    Relationships between student satisfaction and assessment grades in a first-year engineering unit

    Get PDF
    Monitoring the quality of teaching and learning by universities relies primarily upon a combination of feedback from formal student-evaluation surveys and the long-established measure of student-cohort performance in unit assessments. This study explores major factors that might affect the data provided by these two measures and seeks to identify potential relationships between assessment performance and each of student satisfaction and students’ engineering discipline interests. Enabling this study is a large data-set obtained over the last four years from the teaching of a first-year Engineering Mechanics unit delivered twice per year to approximately 350 students in each semester from all engineering and some of multi-science disciplines. Over these years, this unit has largely remained stable in terms of unit learning outcomes, syllabus, delivery methods and teaching staff, thereby permitting potentially robust conclusions to be drawn from analyses of the data-set. By interrogating this data-set, three questions are addressed in this paper, namely (i) Is there a correlation between academic performance and student satisfaction with the unit, (ii) Did a change in assessment weighting affect students’ overall performance, and (iii) Does student interest, as reflected by their engineering-oriented discipline choice, affect their overall assessment outcomes. The investigations presented in this paper are preliminary, focusing on four-semester studies in 2010 and 2011, adopting a broad-brush approach, in order to provide the direction to more refined and rigorous lines of enquiry using the same data to determine the efficacy of present monitoring systems for teaching and learning.The initial results show that student feedback is correlated well to their assessment performance provided that cultural bias is removed. Overall, the influence on performance of changing the assessment weighting appears to be minimal and does the students’ engineering-discipline interests

    On the direct determination of the eigenmodes of finite flow-structure systems

    Get PDF
    If you wish to contact a Curtin researcher associated with this document, you may obtain an email address fro

    Global instabilities and transient growth in Blasius boundary-layer flow over a compliant panel

    Get PDF
    We develop a hybrid of computational and theoretical approaches suited to study the fluid–structure interaction (FSI) of a compliant panel, flush between rigid upstream and downstream wall sections, with a Blasius boundary-layer flow. The ensuing linear-stability analysis is focused upon global instability and transient growth of disturbances. The flow solution is developed using a combination of vortex and source boundary-element sheets on a computational grid while the dynamics of a plate-spring compliant wall are couched in finite-difference form. The fully coupled FSI system is then written as an eigenvalue problem and the eigenvalues of the various flow- and wall-based instabilities are analysed. It is shown that coalescence or resonance of a structural eigenmode with either a flow-based Tollmien–Schlichting Wave (TSW) or wall-based travelling-wave flutter (TWF) modes can occur. This can render the nature of these well-known convective instabilities to become global for a finite compliant wall giving temporal growth of system disturbances. Finally, a non-modal analysis based on the linear superposition of the extracted temporal modes is presented. This reveals a high level of transient growth when the flow interacts with a compliant panel that has structural properties which render the FSI system prone to global instability. Thus, to design stable finite compliant panels for applications such as boundary-layer transition postponement, both global instabilities and transient growth must be taken into account

    A Mesh-Free Compliant-Wall Fluid-Structure Interaction Model

    Get PDF
    This paper presents the development of a numerical algorithm for the simulation of closely coupled fluid-structure interaction (FSI) systems. The particular FSI system investigated in this work involves a high-Reynolds number flow over a single-sided compliant wall section between rigid baffles upstream and downstream. This system is a fundamental analogue of many complex FSI systems found in nature ranging from biomedical applications to drag-reduction using compliant coatings. The present study compares the efficacy of various numerical techniques to resolve the fully-coupled, non-linear FSI dynamics. Of particular interest is the resolution of coupled dynamics at fluid-structure density ratios of approximately unity where typical segmented solution techniques tend to have difficulties. Numerical techniques for resolving these tightly coupled dynamics are crucial to the development of generalized workable grid-free computational methods based on boundary-element and discrete vortex formulations. The flow in this study is represented numerically as an ideal or potential axial flow, however it is important to note that the numerical schemes developed are equally applicable to rotational and viscous flow fields. The flow over the non-linear deforming surface is handled by a boundary-element method formulation of the Laplace equation. The structural dynamics are represented numerically by a finite-difference formulation of the Euler-Bernoulli beam equation.Various algorithms for the coupling of the fluid and structure equations will be tested for their numerical efficiency, stability and overall accuracy. The particular algorithms of note involve the semi-implicit, the linearised fluid inertia and the fully-implicit coupling methods. The compliant-wall is modelled using a one-dimensional (1D), non-linear, Euler-Bernoulli beam model, with the non-linearity captured through an induced tension term. We look at the transient response obtained from the initial value problem, with the solution obtained numerically through an implicit time stepping scheme and the finite difference method (FDM). In all cases, the O(n2) computational complexity that is typical with the numerical solution of a boundary-element formulation is mitigated through the use of a fast-multipole method (FMM) that reduces the complexity to O(n log n). Thus, the numerics are handled in such a way that system matrices are not explicitly formed and thereby avoiding issues of associated memory storage. The results validate well against previously published experimental and numerical work. They show that the semi-implicit method is an efficient computational technique for the solution of low density-ratio FSI problems, however it fails to achieve convergence at high density ratios.The fully-implicit coupling method achieved a good convergence and efficiency in the case of high density ratio models, however it’s computational cost was higher than the semi-implicit method, but still lower than the coupling of the linearised fluid inertia term. Further work in this area will involve using these results to facilitate modelling fluid-structure systems that incorporate the dynamics of full viscous and rotational flow

    A pilot study of e-quiz and e-review programs in the online blended learning of first-year engineering mechanics

    Get PDF
    Background: In traditional teaching philosophy, large-class units such as First-Year Engineering Mechanics have experienced significant challenges with respect to a lack of close lecturer-student interaction, prompt performance feedback, and students’ engagement and self-motivation in the unit study. Online blended learning and self-assessment approaches have become useful tools to reinforce traditional teaching and assessment modes of ‘attending the real lectures’ or to ‘physically sit for the quiz tests’. Their advantage lies in study flexibility and unconstrained self-development of students in the designated unit activities. A pilot study of e-quiz and e-review programs was undertaken in a First-Year Engineering Mechanics unit to evaluate their usefulness in students’ blended learning. Purpose: How to enhance individual students’ unit feedback, minimise the physical constraints of quiz access, and remove the barrier of limited topic-review opportunities is expected to be tackled in this study. Design/Method: The Pearson Mastering Engineering online platform was utilised in the e-quiz practices. This contains interactive self-learning and self-assessment modalities with sufficient hands-on feedback to guide students through an entire set of quiz problems after completing the assessment. The e-review was implemented through Elluminate Live to allow students to participate in weekly online review sessions conducted by the unit lecturer using a graphics tablet. Statistical data were analysed for the user-friendliness of online educational tools, enhanced level of effective learning and the students’ feedback and view of the learning experience.Results: A small number of high-achiever participants tended to best utilise e-quiz program to advance their academic performance when compared to formal assessment components including the in-class quizzes and final examination. Underperforming students (as the majority) presented less interest in the e-quiz primarily due to their ‘assessment-oriented’ mindset. Better understanding of mechanics topics/contents and more engagement and self-motivation were found through the e-quiz surveys. The e-review study suggested that students preferred viewing the recorded e-review sessions to personally participating in the peer-to-peer live consultation. Student participants praised the user-friendly Elluminate Live features in terms of ‘interactive learning’, ‘collaborative learning’ and ‘a sense of learning community’. The usefulness of recorded e-review sessions and comprehensive review materials were also highly commended. Conclusions: The e-quiz pilot study offers great potential to enhance the first-year students’ understanding of complex mechanics concepts and impact positively on their flexible self-evaluation. It particularly facilitates more able students to further advance their achievement levels. The e-review was clearly recognised by students as a supplementary academic support to gain more direct individual interactions with lecturers. The higher utility of e-review materials, especially for viewing recorded e-review sessions, was shown to be beneficial to effective learning. The student disengagement and low participation/survey response numbers are of particular concern, which is anticipated to be altered when both programs are introduced as additional assessment components in the furture study

    e-Review Program: An alternative online interaction for a first-year unit of Engineering Mechanics using a virtual classroom

    Get PDF
    For large first-year units such as Engineering Mechanics 100, a lack of close interactive consultations between individual students and lecturers, and opportunities for weekly topic reviews precludes the enhancement of effective learning outcomes. Such drawbacks can lead to students’ disengagement that ultimately results in their academic underperformance. This e-Review project investigated the effective use of an alternative flexible learning method in which the interactive online teaching tool Elluminate Live was combined with a visual-aid graphics tablet to conduct the weekly e-Review sessions and revisions of past-semester examination questions. As opposed to the conventional in-class review in unit teaching, the difference of the e-Review program lies in its convenient electronic access to unit revision activities through the monitoring of lecturers (as moderators) in a virtual classroom. It is shown that the use of Elluminate Live offers supplementary academic support that is beneficial to students through more direct feedback than can be achieved in a real class. Students also recognise the higher utility of e-Review materials that allow for subsequent viewing of recorded e-Review sessions

    Boundary-Layer Hydrodynamics using Mesh-Free Modelling

    Get PDF
    • …
    corecore