Dynamic Shedding Behavior in the Wake Oo Low-Aspect-Ratio Wall-Mounted Obstacles

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Experimental Observations on Flow Characteristics around a Low-Aspect-Ratio Wall-Mounted Circular and Square Cylinder

The mean wake structures of a cube (square cylinder) and circular cylinder of height-to-width aspect ratio 1.0, at a Reynolds number of 1.78 × 104 based on the obstacle width, were investigated experimentally. The boundary-layer thickness was 0.14 of the obstacle height. The study was performed using thermal anemometry and two-dimensional digital particle image velocimetry (DPIV). Streamwise structures observed in the mean wake for both cylinders included well-known tip- and horseshoe (HS)-,vortex pairs as well as additional structures akin to the base vortices. In addition to tip-, base-, and HS-vortices, in the near wake of the cube, two more counter-rotating pairs of streamwise structures, including upper and inboard vortices, were observed. The existence of base vortices formed in the near wake for both obstacles is a unique observation and has not been previously reported for such low-aspect-ratio obstacles in thin boundary-layers. A model of arch-vortex evolution was proposed, in which arch structures were deformed by the external shear-flow to explain the observed base-vortices in the cylinder wake. A weak dominant-frequency of St = f0D/U∞ = 0.114 was observed across the height for the cube, while no discernible spectral peaks were apparent in the wake of the cylinder. Cross-spectral analysis revealed the shedding to be symmetric (in-phase) arch-type for the cylinder and predominantly anti-symmetric (out-of-phase) Karman-type for the cube. The study makes fundamental contributions to the understanding of the flow-field surrounding low-aspect-ratio cylinders

Midwifery students’ experiences : Violations of dignity during childbirth

Background The principle of human dignity is woven into the ethical principles of the midwifery profession, noted as both an obligation and a human right. Research Objectives The aim of this study is to explore the experiences of midwifery students regarding threats to women's dignity during childbirth. Research Design This is a qualitative study with explorative design. Participants and Research Context: The research was carried out in 2022 at Kermanshah University of Medical Sciences, involving 32 midwifery students in individual interviews that lasted between 30 and 90 minutes. These participants aged 21 to 28 years, with an average age of 23.5 years, provided their perspectives on the matter. Results Four key themes described the threats to women?s dignity during childbirth: 1) professional incompetence, 2) abuse of power imbalance, 3) caring only for physical and not mental health, and 4) structural issues within the healthcare system. Professional incompetence was characterized by outdated practices and lack of adherence to evidence-based medicine. Abuse of power imbalance was demonstrated in instances where the authoritative position of healthcare providers was misused, thereby disrupting the respectful care that women are entitled to receive. The disproportionate emphasis on physical health over mental health was evidenced by the disregard for mothers' psychological well-being during childbirth. Lastly, systemic structural issues emerged as significant impediments, revealing the need for system-wide changes. Ethical considerations: This study was approved by the Ethics Committee of the Research Deputy at Kermanshah University. Participation was voluntary and the confidentiality were maintained. Conclusion The findings underscore the role that unprofessional behavior, ethical lapses in medical practices, and systemic challenges play in undermining maternal dignity during childbirth. These threats necessitate urgent attention and must be adequately addressed in policy development and program implementation to safeguard the dignity of mothers during childbirth

The Evaluation of Iranian midwifery Ph.D. course based on the CIPP model

Background: A high-quality Ph.D. course requires frequent assessment and identification of deficiencies and limitations. The midwifery Ph.D. course started in 2016 in Iran and since no evaluation has been performed on this program, the present study aimed to evaluate the Iranian midwifery Ph.D. course based on the CIPP model.Method: This descriptive-evaluative research was conducted based on the CIPP model in 2021 in the schools of nursing and midwifery of Tabriz and Ahvaz Universities of medical sciences, Iran. The statistical population included the faculty members of the midwifery Ph.D. program (9 individuals) and midwifery Ph.D. graduates and students (21 individuals). The data collection tools comprised CIPP-based questionnaires exclusively for faculty members and students. Descriptive statistics were employed for data analysis.Results: Most students (81%) and faculty members (77.8%) reported an appropriate general evaluation of the midwifery Ph.D. curriculum. Most faculty members (77.8%) and students (90.8%) reported the indicators of the midwifery Ph.D. curriculum as appropriate in terms of context. More than three forth of faculty members (77.8%) and more than half of the students (57.1%) reported this curriculum as appropriate regarding input. This program was also reported to be appropriate according to 52.4% of students and 66.7% of faculty members in terms of process. Furthermore, a total of 66.7% of participants in both groups reported an appropriate status in terms of output.Conclusion: Midwifery Ph.D. curriculum was reported as an appropriate program. Also, students of this discipline requested greater stress on clinical upskilling for midwifery Ph.D

Effects of bedforms and large protruding grains on near-bed flow hydraulics in low relative submergence conditions

In mountain rivers, bedforms, large relatively immobile grains, and bed texture and topographic variability can significantly alter local and reach-averaged flow characteristics. The low relative submergence of large immobile grains causes highly three-dimensional flow fields that may not be represented by traditional shear stress, flow velocity, and turbulence intensity equations. To explore the influence of large protruding grains and bedforms on flow properties, we conducted a set of experiments in which we varied the relative submergence while holding the sediment transport capacity and upstream sediment supply constant. Flow and bed measurements were conducted at the beginning and end of each experiment to account for the absence or presence of bedforms, respectively. Detailed information on the flow was obtained by combining our measurements with a 3D numerical model. Commonly used velocity profile equations only performed well at the reach scale when shallow flow effects and the roughness length of the relatively mobile sediment were considered. However, at the local scale large deviations from these profiles were observed and simple methods to estimate the spatial distribution of near-bed shear stresses are likely to be inaccurate. Zones of high turbulent kinetic energy occurred near the water surface and were largely controlled by the immobile grains and plunging flow. The reach-averaged shear stress did not correlate to depth or slope, as commonly assumed, but instead was controlled by the relative boulder submergence and degree of plunging flow. For accurate flow predictions in mountain rivers, the effects of bedforms and large boulders must be considered