A comparison of two central difference schemes for solving the Navier-Stokes equations

Five viscous transonic airfoil cases were computed by two significantly different computational fluid dynamics codes: An explicit finite-volume algorithm with multigrid, and an implicit finite-difference approximate-factorization method with Eigenvector diagonalization. Both methods are described in detail, and their performance on the test cases is compared. The codes utilized the same grids, turbulence model, and computer to provide the truest test of the algorithms. The two approaches produce very similar results, which, for attached flows, also agree well with experimental results; however, the explicit code is considerably faster

Parent Satisfaction with Marshall University’s Summer Enrichment Program: Year Three

The current study sought to examine the level of parent satisfaction with an extended school year program, the Marshall University Graduate College Summer Enrichment Program, verses the level of parent satisfaction at students’ local schools. The study also replicated the findings in two previous studies (Lattimore, 2003; Wartenburg, 2005). Parent satisfaction data were collected using satisfaction surveys. A survey was mailed to parents at the end of the regular school year to assess level of parent satisfaction with local school (N= 105). Twenty surveys were returned by mail. Intercorrelations of the parent satisfaction survey questions for the local school were made with the original satisfaction measure on question 14. Ten significant correlations were made at the .001 level and were used to develop the new parent satisfaction with local school measure. The average score for the level of parent satisfaction with the students’ local school was 3.85 (SD= 1.29). A second survey was mailed the week after the summer program concluded to assess the level of parent satisfaction with the MUGC Summer Enrichment Program (N=105). Twenty-one were returned by mail. Intercorrelations of the parent satisfaction survey questions for the MUGC Summer Enrichment Program were made with the original satisfaction measure on question 14. Ten significant correlations were made at the .001 level and were used to develop the new parent satisfaction with the MUGC Summer Enrichment Program measure. The average score for the overall level of parent satisfaction with the MUCG Summer Enrichment program of 4.68 (SD= 0.67). A t-test analysis on the twenty returned parent surveys found that the variable #10 (My child was safe at school was the best indicator of parent satisfaction with the local school and that the variable #10 (My child was safe at school) was the best indicator of the parent satisfaction with the MUGC Summer Enrichment Program. On the basis of self-report, the 41 responses from the 2005 surveys were combined and assigned to three groups, no involvement, giving and receiving information, and having control over decisions. An ANOVA was performed on the returned parent surveys found that parents who had medium participation (giving and receiving information) in the summer program had high satisfaction with their school program and parents who had medium participation (giving and receiving information) in the summer program had high with the MUGC Summer Enrichment Program. Overall, this analysis found that parents who had some level of involvement were more satisfied than parents who had less involvement. Additionally, the level of parent satisfaction with the MUGC Summer Enrichment Program throughout the past three years was compared by using a 3x3 Chi Square analysis of categorical variables for question 14 (“I am satisfied with the MUGC Summer Enrichment Program”). Data found that overall level of parent satisfaction with the MUGC Summer Enrichment Program increased throughout the past three years of the program. Satisfaction levels were also higher with the chosen program (MUGC Summer Enrichment Program satisfaction Mean 4.68; SD 0.67) than with the mandatory local program (Local School Mean 3.85; SD 1.29)

Navier-Stokes computations for circulation control airfoils

Navier-Stokes computations of subsonic to transonic flow past airfoils with augmented lift due to rearward jet blowing over a curved trailing edge are presented. The approach uses a spiral grid topology. Solutions are obtained using a Navier-Stokes code which employs an implicit finite difference method, an algebraic turbulence model, and developments which improve stability, convergence, and accuracy. Results are compared against experiments for no jet blowing and moderate jet pressures and demonstrate the capability to compute these complicated flows

Computational Analysis of Multi-Rotor Flows

Interactional aerodynamics of multi-rotor flows has been studied for a quadcopter representing a generic quad tilt-rotor aircraft in hover. The objective of the present study is to investigate the effects of the separation distances between rotors, and also fuselage and wings on the performance and efficiency of multirotor systems. Three-dimensional unsteady Navier-Stokes equations are solved using a spatially 5th order accurate scheme, dual-time stepping, and the Detached Eddy Simulation turbulence model. The results show that the separation distances as well as the wings have significant effects on the vertical forces of quadroror systems in hover. Understanding interactions in multi-rotor flows would help improve the design of next generation multi-rotor drones

OVERFLOW Turbulence Modeling Resource Validation Results

Abstract:We exercise the computational fluid dynamics code OVERFLOW on sixteen turbulence model validation cases from the NASALangley Turbulence Model Resource web site. We give some information about the OVERFLOW options used to run these cases, and compare OVERFLOW results with results from other codes and with experiment. The goal is turbulence model validation for OVERFLOW

Contributions to HiLiftPW-3 Using Structured, Overset Grid Methods

The High-Lift Common Research Model (HL-CRM) and the JAXA Standard Model (JSM) were analyzed computationally using both the OVERFLOW and LAVA codes for the third AIAA High-Lift Prediction Workshop. Geometry descriptions and the test cases simulated are described. With the HL-CRM, the effects of surface smoothness during grid projection and the effect of partially sealing a flap gap were studied. Grid refinement studies were performed at two angles of attack using both codes. For the JSM, simulations were performed with and without the nacelle/pylon. Without the nacelle/pylon, evidence of multiple solutions was observed when a quadratic constitutive relation is used in the turbulence modeling; however, using time-accurate simulation seemed to alleviate this issue. With the nacelle/pylon, no evidence of multiple solutions was observed. Laminar-turbulent transition modeling was applied to both JSM configuration, and had an overall favorable impact on the lift predictions

Mind the gap: Patterns of red blood cell product usage in South Africa, 2014 - 2019

Background. A key component of any successful healthcare system is the availability of sufficient, safe blood products delivered in an equitable manner. South Africa (SA) has a two-tiered healthcare system with public and privately funded sectors. Blood utilisation data for both sectors are lacking. Evaluation of blood utilisation patterns in each healthcare sector will enable implementation of systems to bring about more equality.Objectives. To conduct a critical evaluation of red blood cell (RBC) product utilisation patterns at the South African National Blood Service (SANBS).Methods. Operationally collected data from RBC requests submitted to SANBS blood banks for the period 1 January 2014 - 31 March 2019 were used to determine temporal RBC product utilisation patterns by healthcare sector. Demographic patterns were determined, and per capita RBC utilisation trends calculated.Results. Of the 2 356 441 transfusion events, 65.9% occurred in the public and 34.1% in the private sector. Public sector patients were younger (median (interquartile range (IQR)) 33 (22 - 49) years) than in the private sector (median (IQR) 54 (37 - 68) years), and mainly female in both sectors (66.2% in the public sector and 53.4% in the private sector). Between 2014 and 2018, per capita RBC utilisation decreased from 11.9 to 11.0/1 000 population in the public sector, but increased from 34.8 to 38.2/1 000 population in the private sector.Conclusions. We confirmed distinctly different RBC utilisation patterns between the healthcare sectors in SA. Possible drivers for these differences may be healthcare access, differing patient populations and prescriber habits. Better understanding of these drivers may help inform equitable public health policy

Drag Prediction for the NASA CRM Wing-Body-Tail Using CFL3D and OVERFLOW on an Overset Mesh

In response to the fourth AIAA CFD Drag Prediction Workshop (DPW-IV), the NASA Common Research Model (CRM) wing-body and wing-body-tail configurations are analyzed using the Reynolds-averaged Navier-Stokes (RANS) flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built for DPW-IV. Grid Family 1 (GF1) consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 (GF2) is an extension of the first and includes a superfine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on GF1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on GF1 and to obtain results for GF2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes

Contributions to the Sixth Drag Prediction Workshop Using Structured, Overset Grid Methods

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143028/1/1.C034486.pd