Grid adaption for bluff bodies

Methods of grid adaptation are reviewed and a method is developed with the capability of adaptation to several flow variables. This method is based on a variational approach and is an algebraic method which does not require the solution of partial differential equations. Also the method was formulated in such a way that there is no need for any matrix inversion. The method is used in conjunction with the calculation of hypersonic flow over a blunt nose. The equations of motion are the compressible Navier-Stokes equations where all viscous terms are retained. They are solved by the MacCormack time-splitting method and a movie was produced which shows simulataneously the transient behavior of the solution and the grid adaptation. The results are compared with the experimental and other numerical results

Numerical solutions of 3-dimensional Navier-Stokes equations for closed bluff-bodies

The Navier-Stokes equations are solved numerically. These equations are unsteady, compressible, viscous, and three-dimensional without neglecting any terms. The time dependency of the governing equations allows the solution to progress naturally for an arbitrary initial guess to an asymptotic steady state, if one exists. The equations are transformed from physical coordinates to the computational coordinates, allowing the solution of the governing equations in a rectangular parallelepiped domain. The equations are solved by the MacCormack time-split technique which is vectorized and programmed to run on the CDc VPS 32 computer. The codes are written in 32-bit (half word) FORTRAN, which provides an approximate factor of two decreasing in computational time and doubles the memory size compared to the 54-bit word size

Topology and grid adaption for high-speed flow computations

This study investigates the effects of grid topology and grid adaptation on numerical solutions of the Navier-Stokes equations. In the first part of this study, a general procedure is presented for computation of high-speed flow over complex three-dimensional configurations. The flow field is simulated on the surface of a Butler wing in a uniform stream. Results are presented for Mach number 3.5 and a Reynolds number of 2,000,000. The O-type and H-type grids have been used for this study, and the results are compared together and with other theoretical and experimental results. The results demonstrate that while the H-type grid is suitable for the leading and trailing edges, a more accurate solution can be obtained for the middle part of the wing with an O-type grid. In the second part of this study, methods of grid adaption are reviewed and a method is developed with the capability of adapting to several variables. This method is based on a variational approach and is an algebraic method. Also, the method has been formulated in such a way that there is no need for any matrix inversion. This method is used in conjunction with the calculation of hypersonic flow over a blunt-nose body. A movie has been produced which shows simultaneously the transient behavior of the solution and the grid adaption

Application of the method of lines for solutions of the Navier-Stokes equations using a nonuniform grid distribution

The feasibility of the method of lines for solutions of physical problems requiring nonuniform grid distributions is investigated. To attain this, it is also necessary to investigate the stiffness characteristics of the pertinent equations. For specific applications, the governing equations considered are those for viscous, incompressible, two dimensional and axisymmetric flows. These equations are transformed from the physical domain having a variable mesh to a computational domain with a uniform mesh. The two governing partial differential equations are the vorticity and stream function equations. The method of lines is used to solve the vorticity equation and the successive over relaxation technique is used to solve the stream function equation. The method is applied to three laminar flow problems: the flow in ducts, curved-wall diffusers, and a driven cavity. Results obtained for different flow conditions are in good agreement with available analytical and numerical solutions. The viability and validity of the method of lines are demonstrated by its application to Navier-Stokes equations in the physical domain having a variable mesh

Extension of multigrid methodology to supersonic/hypersonic 3-D viscous flows

A multigrid acceleration technique developed for solving 3-D Navier-Stokes equations for subsonic/transonic flows was extended to supersonic/hypersonic flows. An explicit multistage Runge-Kutta type of time stepping scheme is used as the basic algorithm in conjunction with the multigrid scheme. Solutions were obtained for a blunt conical frustum at Mach 6 to demonstrate the applicability of the multigrid scheme to high speed flows. Computations were performed for a generic High Speed Civil Transport configuration designed to cruise at Mach 3. These solutions show both the efficiency and accuracy of the present scheme for computing high speed viscous flows over configurations of practical interest

Assessors' attitudes toward and experiences of national quality standards: A qualitative study in Iran

To establish a national accreditation system for medical laboratories, Iran has set national standards based on the international standard ISO 15189. Central to the accreditation process are the technical assessors. Their attitude in this regard and their experiences should be identified. This study aims to explore assessors' attitudes toward national laboratory accreditation and their experiences of assessment process in order to identify current gaps and suggest required interventions to solve them. A qualitative study using an open-ended questionnaire was employed. A total of 150 assessors working in the General Directorate of Laboratory Affairs participated in the study. While almost all Iranian laboratory accreditation assessors were generally supportive about the necessity of laboratory accreditation and cited benefits of this process, they pointed to improvement areas including developing assessor selection and appraisal criteria, continuous training, taking into consideration the heterogeneity of laboratories throughout the country, participation of professional associations and adopting measures to increase laboratories' involvement. © 2014 Springer-Verlag Berlin Heidelberg

Impact of urine and mixed incontinence on long-term care preference: a vignette-survey study of community-dwelling older adults.

In view of population aging, a better knowledge of factors influencing the type of long-term care (LTC) among older adults is necessary. Previous studies reported a close relationship between incontinence and institutionalization, but little is known on opinions of older citizens regarding the most appropriate place of care. This study aimed at evaluating the impact of urine and/or fecal incontinence on preferences of community-dwelling older citizens. We derived data from the Lausanne cohort 65+, a population-based study of individuals aged from 68 to 82 years. A total of 2974 community-dwelling persons were interviewed in 2017 on the most appropriate place of LTC delivery for three vignettes displaying a fixed level of disability with varying degrees of incontinence (none, urinary, urinary and fecal). Multinomial logistic regression analyses explored the effect of respondents' characteristics on their opinion according to Andersen's model. The level of incontinence described in vignettes strongly determined the likelihood of considering institutional care as most appropriate. Respondents' characteristics such as age, gender, educational level, being a caregiver, knowledge of shelter housing or feeling supported by family influenced LTC choices. Self-reported incontinence and other indicators of respondents' need, however, had no significant independent effect. Among older community-dwelling citizens, urinary and fecal incontinence play a decisive role in the perception of a need for institutionalization. Prevention and early initiation of support for sufferers may be a key to prevent this need and ensure familiar surrounding as long as possible

Stakeholders' perspective on health equity and its indicators in Iran: A qualitative study

Background: To reduce the health inequity, it is necessary to measure and monitor these inequalities. In this regard, in Iran a plan was developed and accordingly 52 indicators to measure equity in health were developed and announced by the Ministry of Health in collaboration with other sectors. This study aims to obtain a deeper understanding of the development of health equity indicators and identify their implementation challenges and proposed solutions from the perspective of policy makers and executives responsible for the indicators development and implementation. Methods: In this qualitative study, data were gathered using semi-structured interviews with 15 Stakeholders involved in the development and implementation of these health equity indicators (at national and provincial levels), and the review and analysis of relevant documents including meeting minutes, working plans and working progress reports. Data were analyzed using a framework analysis approach. Results: Four main themes were identified, including the concept of equity in health and its importance, the use of health equity indicators and process of indicators development, challenges of development and implementation of the indicators and laying the groundwork for the establishment of indicators. The findings showed that policy makers' viewpoint on concepts and indicators is different from those of executives and their perceptions have little in common. The establishment of indicators requires accurate stakeholders' understanding and accurate insight into the issue of equity in health, political will, financing, training and empowerment of organization's employees, legal requirements, and finally a clear action plan. Conclusion: The development of the indicators requires a shared understanding among policy makers and executives. As the attention has been focused recently on the issue, in addition to knowledge improvement, proper solutions with an intersect oral collaboration approach in order to tackle challenges should be considered

Determinants of change in polypharmacy status in Switzerland: the population-based CoLaus study.

This study aimed to assess the prevalence, the change, and the determinants of change in polypharmacy in a population-based sample. Baseline (2003-2006) and follow-up (2009-2012) data are from 4679 participants aged between 35 and 75 years (53.5% women, mean age 52.6 ± 10.6 years) from the population of Lausanne, Switzerland. Polypharmacy was defined by the regular use of ≥5 drugs. Four categories of change were defined: never (no polypharmacy at baseline and follow-up), initiating (no polypharmacy at baseline but at follow-up), maintaining, or quitting. Polypharmacy increased from 7.7% at baseline to 15.3% at follow-up. Cardiovascular drugs were the most prescribed medicines at baseline and follow-up. Gender, age, obesity, smoking, previously diagnosed hypertension, or diabetes or dyslipidemia were significantly and independently associated with initiating and maintaining polypharmacy. In a population-based sample, prevalence of polypharmacy doubled over a 5.6-year period. The main determinants of initiating polypharmacy were age, overweight and obesity, smoking status, and previously diagnosed cardiovascular risk factors

Polypill eligibility and equivalent intake in a Swiss population-based study.

The polypill has been advocated for cardiovascular disease (CVD) management. The fraction of the population who could benefit from the polypill in Switzerland is unknown. Assess (1) the prevalence of subjects (a) eligible for the polypill and (b) already taking a polypill equivalent; and (2) the determinants of polypill intake in the first (2009-2012) and second follow-ups (2014-2017) of a population-based prospective study conducted in Lausanne, Switzerland. The first and the second follow-ups included 5038 and 4596 participants aged 40-80 years, respectively. Polypill eligibility was defined as having a high CVD risk as assessed by an absolute CVD risk ≥ 5% with the SCORE equation for Switzerland and/or presenting with CVD. Four polypill equivalents were defined: statin + any antihypertensive with (A) or without (B) aspirin; statin + calcium channel blocker (CCB) (C); and statin + CCB + angiotensin-converting enzyme inhibitor (D). The prevalence of polypill eligibility was 20.6% (95% CI 19.5-21.8) and 27.7% (26.5-29.1) in the first and second follow-up, respectively. However, only around one-third of the eligible 29.5% (95% CI 26.7-32.3) and 30.4% (27.9-33.0) respectively, already took the polypill equivalents. All polypill equivalents were more prevalent among men, elderly and in presence of CVD. After multivariable adjustment, in both periods, male gender was associated with taking polypill equivalent A (OR: 1.93; 95% CI 1.45-2.55 and OR: 1.67; 95% CI 1.27-2.19, respectively) and polypill equivalent B (OR: 1.52; 95% CI 1.17-1.96 and OR: 1.41; 95% CI 1.07-1.85, respectively). Similarly, in both periods, age over 70 years, compared to middle-age, was associated with taking polypill equivalent A (OR: 11.71; CI 6.74-20.33 and OR: 9.56; CI 4.13-22.13, respectively) and equivalent B (OR: 13.22; CI 7.27-24.07 and OR: 20.63; CI 6.51-56.36, respectively). Former or current smoking was also associated with a higher likelihood of taking polypill equivalent A in both periods. A large fraction of the population is eligible for the polypill, but only one-third of them actually benefits from an equivalent, and this proportion did not change over time