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Over the past several decades, computational fluid dynamics has been increasingly used in the aerospace industry for the design and study of new and derivative aircraft. In this review we survey the CFD application process and note its place and importance within the everyday work of industry. Furthermore, the centrality of geometry and importance of turbulence models, higher-order numerical algorithms, output-based mesh adaptation, and numerical design optimization are discussed. Challenges in each area are noted and specific suggestions for investment are made. The review concludes with an outlook toward a future in which certification by analysis and model-based design are standard practice, along with a reminder of the steps necessary to lead the industry there.

Objective: Patients (F508del/F508del or F508del/MF) with severe CF (ppFEV1

Background: Patients often contact the cystic fibrosis (CF) multidisciplinary team (MDT) via phone to express health-related concerns in between the standard quarterly review. This often requires a phone evaluation before organising an unscheduled appointment. These sporadic interactions heavily affect available resources. This strain on resources will be further impacted when considering that data from the European CF registry predicts that there will be a 75% increase in the adult CF population by 2025. Furthering this, CF services are increasingly more strained now during the global Covid-19 pandemic. Objective: This research first sets about to design and develop a Virtual Doctor system based on the expertise of a MDT through multiple consultations. Next, pilot data pertaining to user acceptance and experience with using this novel technology is gathered. We therefore aim to investigate if the use of such technology can be beneficial in a specific clinical setting. Method: The final collaborative-design of the Virtual Doctor comprises several technical features and is primarily a voice synthesis system allowing the patient to interact with natural language. The virtual doctor asks the patient questions regarding their health concerns and can collect real-time clinical metrics such as FEV1, oxygen saturation, temperature. The patients’ responses and metrics are then compared to baseline values calculating a score which stratifies a response time from the CF team. This information is then collated in a report and sent to the CF team for action. Future works: Initial stress testing of the technical performance is now complete. Supportive visual media to improve coaching of using clinical devices have now been implemented in preparation for patient pilot testing which is currently ongoing. It is anticipated that a virtual system such as the Virtual Doctor will become more accessible and acceptable to patients, especially during the Covid-19 pandemic.

Reactive flow models have been used to design explosive trains and predict explosive response to various shock inputs. Parametrization of these models can be determined using short-duration shock data from thin flyers for ignition behavior and sustained pulse Pop-plot data for growth to detonation behavior. The latter was measured in an explosive using 4 experimental configurations with different data collection techniques. Two were gas-gun driven 1-D shock waves with either embedded particle velocity gauges or photon Doppler velocimetry at the end of different sample thicknesses. The other two were explosive donors to produce either a 1-D or quasi-1-D shock wave in wedge or cylindrical acceptors, respectively. Break out of the detonation wave in wedge samples was observed by streak camera, while embedded time of arrival gauges were used for cylindrical samples. Run-distances were compared between all 4 cases using a consistent method involving the intersection of two linear fits through data prior to and after transiting to detonation. All methods provided consistent data, indicating that one or more combinations of these methods are suitable for parameterizing a reactive flow model.

The Common Research Model used by the Fourth Drag Prediction Workshop was employed to investigate the accuracy of three primary codes used at The Boeing Company for transonic aerodynamic flow analysis. The codes used in this study are CFL3D (block structured), OVERFLOW (overset structured), and BCFD (unstructured). Solutions were obtained for a wing/body configuration, with the horizontal tail at incidence angles of 0, +2, −2 deg, and with the tail removed. Grid convergence and resolution, mesh topology, and turbulence models were considered the primary factors in this study for accurate predictions of cruise drag, pitching moments, and Reynolds number effects. Also, these factors were considered in wing and tail side-of-body flow separation predictions. In this study, all three cases (one required and two optional) were completed with all three codes. The solutions were obtained with the one-equation turbulence model of Spalart and Allmaras and the two-equation shear-stress transport turbulence model of...

Two general-purpose Reynolds-averaged Navier–Stokes flow solvers, OVERFLOW and BCFD, are used to analyze the NASA Common Research Model in a wing–body configuration. The codes are run on structured and unstructured common-grid families built specifically for the Fifth AIAA CFD Drag Prediction Workshop, allowing for a meaningful comparison of data. The results from a grid-convergence study are evaluated for each solver and grid type with focus on isolating individual effects of turbulence model and differencing scheme on computed forces, moments, and wing pressures. A medium mesh consisting of 5.1 million cells is used for a buffet-onset study to better understand variations in high-speed wing-separation prediction driven by the strengthening shock and by corner-flow physics at the wing–body juncture. Numerical simulation of side-of-body separation continues to be a challenge for Reynolds-averaged Navier–Stokes methods, in which solutions are sensitive to grid density and turbulence model, among other vari...

In order to simulate the motion of bubbles, drops, and particles, it is often important to consider finite Reynolds number effects on drag, lift, torque, and history force. Herein, an equation of motion is developed for spherical particles with a no-slip surface based on theoretical analysis, experimental data, and surface-resolved simulations. The equation of motion is then extended to account for finite particle size. This extension is critical for particles which will have a size significantly larger than the grid cell size, particularly important for bubbles, and low-density particles. The extension to finite particle size is accomplished through spatial-averaging (both volume-based and surface-based) of the continuous flow properties. This averaging is consistent with the Faxen limit for solid spheres at small Reynolds numbers and added mass and fluid stress forces at inviscid limits. The finite Re p corrections are shown to have good agreements with experiments and resolved-surface simulations. The finite size corrections are generally fourth-order accurate and an order of magnitude more accurate than point-force expressions (which neglect quadratic and higher spatial gradients) for particles with size on the order of the gradient length-scales. However, further work is needed for more quantitative assessment of the truncation terms and the overall model robustness and accuracy in complex flows.

The objective of this paper is to describe a modified method and to present our results for stabilization of the vertebral column to the pelvis in patients with neuromuscular scoliosis. This technique attempts to address difficulties posed by distal fixation in such cases. A retrospective review of nine consecutive patients with neuromuscular scoliosis was carried out. All patients in this group had surgical correction between 1999 and 2002. Immediate post-operative mean corrections of 65.1° (Cobb angle) and 10.6° (pelvic obliquity) were obtained. Mean follow-up time was 39 months (range: 36–48). Mean operating times of 497 min and mean blood loss of 57.2 ml/kg body weight were achieved. All patients reached clinical and radiological spinal fusion with no loss of correction seen at latest follow-up visit. Obtaining adequate distal fixation with the standard Luque–Galveston technique can be difficult in patients with neuromuscular scoliosis who often have a porotic pelvis. These difficulties can be minimised by the modified technique described in this paper.

This work gives the thermodynamically consistent theoretical formulations and the numerical implementation of a plasticity model fully coupled with damage. The formulation of the elasto-plastic-damage behavior of materials is introduced here within a framework that uses functional forms of hardening internal state variables in both damage and plasticity. The damage is introduced through a damage mechanics framework and utilizes an anisotropic damage measure to quantify the reduction of the material stiffness. In deriving the constitutive model, a local yield surface is used to determine the occurrence of plasticity and a local damage surface is used to determine the occurrence of damage. Isotropic hardening and kinematic hardening are incorporated as state variables to describe the change of the yield surface. Additionally, a damage isotropic hardening is incorporated as a state variable to describe the change of the damage surface. The hardening conjugate forces (stress-like terms) are general nonlinear functions of their corresponding hardening state variables (strain-like terms) and can be defined based on the desired material behavior. Various exponential and power law functional forms are studied in this formulation. The paper discusses the general concept of using such functional forms. however, it does not address the relevant appropriateness of certain forms to solve different problems. The proposed work introduces a strong coupling between damage and plasticity by utilizing damage and plasticity flow rules that are dependent on both the plastic and damage potentials. However, in addition to that the coupling is further enhanced through the use of the functional forms of the hardening variables introduced in this formulation. The use of this formulation in solving boundary value problems will be presented in future work. The fully implicit backward Euler scheme is developed for this model to be solved in a Newton–Raphson solution procedure.

The thermodynamically consistent formulation and the subsequent numerical implementation of a gradient-enhanced, continuum-coupled damage-plasticity model as a constitutive framework to model ill-posed localization problems is presented. The formulation of the elastoplastic-damage behavior of materials is introduced here within a framework that uses functional forms of hardening internal state variables in both damage and plasticity. Various exponential and power law functional forms are studied in this formulation. Gradients of hardening terms are found directly by operating on the respective hardening terms, and numerical methods are used to compute these gradients. The gradient-enhanced measure used in this work is justified by an approximation to nonlocal theory; however, through the expansion of various gradient terms in this nonlinear hardening plasticity model, gradients of both odd and even orders are introduced into the constitutive model. A multifield method is used such that the displacement field is interpolated using standard continuous elements, and higher-order elements (cubic Hermitian) are used for the plastic multiplier and for the damage multiplier to enforce continuity of the second-order gradients. The effectiveness of the model is evaluated by studying the mesh-dependence issue in localization problems through numerical examples.

Chronic rhinosinusitis (CRS) is very prevalent in the cystic fibrosis (CF) patient population, and leads to high morbidity and markedly decreased quality of life (QOL). Identification of genetic markers that contribute to CRS symptoms in these patients can allow for risk stratification and tailoring of medical and surgical treatments. T2R38 is a bitter taste receptor expressed in the sinonasal tract, and nonfunctional alleles of this receptor have been implicated in treatment-refractory CRS in non-CF patients. The purpose of this study is to investigate the significance of T2R38 genotype in the variability of sinonasal QOL and CRS disease severity in a sample of CF patients.ΔF508 homozygous CF patients were recruited from the University of Pennsylvania Cystic Fibrosis Center and were genotyped for the TAS2R38 locus. To assess sinonasal symptom severity, a 22-item Sino-Nasal Outcome Test (SNOT-22) was collected from each patient. Additional demographic and medical history data was obtained at the time of patient enrollment.A total of 49 ΔF508 homozygous CF patients aged 18 to 32 years were included in the final SNOT-22 score analysis. Individuals with 2 functional T2R38 alleles (PAV/PAV) had significantly lower SNOT-22 scores (n = 49, p0.05). On further breakdown of SNOT-22 subcategories, rhinologic symptoms specifically were less severe in PAV/PAV patients than patients with other genotypes (n = 47, p0.05).Our investigation indicates that T2R38 genotype correlates both with SNOT-22 scores and rhinologic-specific QOL in ΔF508 homozygous CF patients.

The numerical implementation of a gradient-enhanced continuum coupled damage—plasticity model as a constitutive framework to model the nonlocal response of materials is presented. By the introduction of “nonlocal, ” gradient-enhanced measures in the plasticity potential function and yield criterion and in the damage potential function and damage criterion, the proposed model introduces microstructural characteristic material length scales, which allow us to predict the size of localized zones based on material constants, as opposed to local models where the loss of ellipticity causes localized zones to be mesh dependent. As numerical methods are used to compute the gradients of the hardening terms, no additional gradient internal state variables are introduced into the Helmholtz free energy. As opposed to previous theories that only incorporate linear hardening, the gradient model proposed here uses coupled nonassociative plasticity — nonassociative damage and can account for a wide range of material models because of the consistently expanded Laplacian evolution equations. However, due to the nonassociative material model, anisotropic hardening, and the corresponding gradients in plasticity, the model becomes highly complex as additional equations have to be introduced for the evolution of the gradients of plastic normal, plastic strains, damage normal, and damage tensor. The numerical implementation uses a small deformation finite element formulation and includes the displacements, plastic multiplier, and damage multiplier as nodal degrees of freedom, thus allowing the three fields to have different interpolation functions. Higher-order elements are used for the plastic multiplier and damage multiplier to enforce continuity of the second gradients, which requires the introduction of additional boundary conditions.

A trajectory control problem for simple micro air vehicles (MAVs) is introduced and studied. The MAVs are endowed with the ability to estimate their position and velocity and can control their drag coefficient. The objective of this work is to design a control law for the drag coefficient in order to land the MAV close to a desired streamwise location, after being dropped from an airborne carrier at low altitude. We use a simple model-predictive control law, relying on a two-dimensional time-averaged atmospheric velocity field, which is validated on an unsteady three-dimensional representation of an unstratified atmospheric boundary layer. The simulation results show that the proposed control law results in a significant (10-fold) improvement in the accuracy of the streamwise landing point location, with respect to the uncontrolled case. Similar results are obtained when errors are considered in the location of the release point and in the estimate of the mean flowfield.

In order to predict the observed characteristic width of shear bands in plastic materials, internal length scales have been introduced by the incorporation of higher-order gradients into the constitutive equations. The gradient enhanced constitutive model is derived using consistent thermodynamics for a classical rate-independent J 2 plasticity model with kinematic and isotropic hardening. Second-order gradients are introduced in the plasticity potential function and yield criteria through the use of nonlocal measures, which are introduced for each of the local hardening variables selected to describe the material response. The numerical implementation of the nonlocal continuum plasticity model is also presented. In order to link the gradient approach to the microstructure, a discussion is given in which relations for the gradient theory material parameters are given in terms of the microstructural material parameters.

A thermodynamically consistent framework for the gradient approach in plasticity is proposed. The second order gradient of both the kinematic and the isotropic hardening measures is introduced through the Helmholtz free energy and through the plastic potential function. The macroscale gradients allow one to address the nonlocal behavior of materials and interpret the collective behavior of defects such as dislocations. The macroscale internal state variable and the corresponding gradient term are assumed to be independent internal state variables with respect to each other with different physical interpretations and initial conditions which allows these two different physical phenomena to be identified separately. The Aifantis–Walgraef dislocation model is used to give micromechanically based definitions for the nonlocal coefficients.

A physiologically based mathematical model for muscle activated by Functional Neuromuscular Stimulation (FNS) is presented. This model is developed specifically for skeletal muscle activated using N -lets (sets of N high frequency pulses). The model's ability to capture the variety of non-linear effects observed experimentally when activating FNS muscle with N -lets is demonstrated. General properties of FNS muscle are also exhibited by the model. Using the properties of skeletal muscle captured by this model, strategies for the optimal initiation and control of limb movement and the muscular force generated in this highly non-linear dynamical system are developed

Recent experiments, in which voids are precision cut using a second laser, have been used to study void coalescence. In that study, both the Rice and Tracey model and the Thomason model were shown to have reasonable agreement with experiment results for the copper, in most cases. However, no simulations were performed in which voids were explicitly represented. This article uses finite element simulations to describe void coalescence as observed in copper bar uniaxial tension experiments. Several problems occur when meshing the three-dimensional geometry containing 176 voids, namely element distortion and damage, minimum time step, and appropriate material model parameters. Further, a temporal and spatial convergence study was used to estimate errors, thus, this study helps to provide guidelines for modeling of materials with voids. Finally, we use a Gurson model with Johnson-Cook strength to simulate the void growth. Simulations, using the codes ABAQUS explicit, EPIC, and Presto, agree well with experiments.

Unstructured grid solutions for the first AIAA Propulsion Aerodynamics Workshop (PAW-1) are presented for the S-Duct test case. The BCFD code is applied to custom unstructured grids based on the guidance of the Propulsion Aerodynamics Workshop Committee for appropriate surface grid spacings. The focus of the work is to determine the suitability of CFD to predict the static and total pressure distribution in an offset diffuser. Wall pressures, boundary layer profiles, and average properties at the virtual aerodynamic interface plane (AIP) were collected for a range of grid resolutions, two viscous flux discretizations, and several turbulence modeling options. A grid resolution study demonstrates grid convergence of the wall pressure samples and the effect of turbulence modeling choices are studied with comparison to experimental data provided by the PAW-1 Committee. These results show that the streamline curvature correction for the SpalartAllmaras turbulence model provides superior estimates of the wall-pressure compared to other options. Experimental data collected on a total pressure rake located at the AIP were compared to data extracted from the CFD simulations at the total pressure probe locations. The CFD simulations are shown to provide a reasonably accurate prediction of recovery regardless of turbulence model; however, less accuracy was obtained in the measure of distortion. This may be a result of not including the total pressure rake in the CFD model.

A two-equation SST-based RANS/LES model has been refined and improved upon in the BCFD code. Attention is given to improving the model’s ability to transition to LES more rapidly, leading to improved results in massively separated flows. Further attention is given to the manner in which the RANS region is protected from grid induced separation. A comparison of various functions leading to a grid induced separation shield is reported. Results are presented for isotropic turbulence and a NACA 0021 at high angle of attack, in which the new approach is compared to popular alternatives.

This report summarizes a simple extension of a quadratic constitutive relation for the Reynolds stresses applied to unsteady flows. The extension allows DES behavior while retaining the advantages of not directly employing the eddy viscosity hypothesis in the RANS layer. Results are compared to two eddy viscosity models. The goal of this work is to present an unsteady turbulence model approach which has features of more complex models, but the simplicity of eddy viscosity approaches. While the ideas presented here are not new, the method which they are applied is new and of use to CFD engineers. Results are presented for isotropic turbulence, where energy spectra and turbulence statistics are examined in detail.

Background: Background Parenchymal Enhancement (BPE) in a dynamic contrast enhanced (DCE)MRI refers to change in morphology and temporal degree of enhancement expressing physiology of breast tissue. Improvements in the analysis and interpretation of BPE have been shown to increase diagnostic accuracy of the MRI. We explored associations of BPE with breast cancer(BC) risk factors and tumor characteristics. Methods: We conducted a retrospective chart review study of 149 women who were treated for BC at the University of Maryland Medical Center(UMMC) between 2003-2015. Institutional Review Board approval was obtained. Subjects had BI-RADS 4,5 or 6 on their mammograms and/or biopsy proven BC. Women with false positive mammograms (n=2), missing BPE grade in their MRI reports (n=6), metastatic BC at diagnosis (n=2), MRIs done outside of a year of diagnosis (n=3), and who followed up outside UMMC (n=1) were excluded. Final analysis included 135 women. We used 1.5T or 3T scanners for DCE MRI. Standard contrast enhanced MRI protocol, T1, T2, and dynamic series were acquired according to American College of Radiology requirements for breast MRI accreditation and interpreted with Maximum Intensity Projection and subtracted imaging. Fellowship-trained breast imagers performed qualitative BPE assessment as per standard BI-RADS classification. BI-RADS classes were grouped as high BPE (BI-RADS moderate and marked) and low BPE (BI-RADS minimal and mild). Multivariable logistic regression was used to assess associations with predictors including individual and tumor characteristics. Results: Preliminary analyses showed BPE was significantly associated with alcohol intake, with drinkers being more likely to have high BPE compared to non-drinkers [odds ratio (OR) =3.08 (95% confidence interval (CI) = 1.34-7.09; p=0.008]. Women who received adjuvant radiation for their BC were less likely to have high BPE compared to women who did not undergo radiation [OR= 0.37 (95% CI=0.15-0.90); p=0.03] implying higher likelihood of breast conservation surgery in the former group. High BPE was less often observed for invasive ductal carcinoma histology vs. in-situ ductal carcinomas [OR= 0.40 95% CI=0.16-1.00); p=0.05] and in post- vs. premenopausal women [OR=0.47 (95%CI=0.22-1.00); p=0.05]. No association was found between BPE and race, BMI, prior HRT/OCP use, smoking, or ER/PR/HER-2 status. Conclusion: We observed association between higher BPE and alcohol exposure and lower BPE and, invasive ductal histology, postmenopausal status at diagnosis of BC and adjuvant radiation for BC. Larger studies are needed to corroborate our findings and identify the underlying mechanisms. Citation Format: Iyer L, Faramand R, Jung S, Rosenblatt P, Campassi C, Dromi S, Dorgan J, Tkaczuk K. Association of background parenchymal enhancement with breast cancer risk factors and tumor characteristics [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-02-08.

*† ‡ § ** †† ‡‡ Two general purpose Reynolds Averaged Navier-Stokes (RANS) flow solvers, OVERFLOW and BCFD, are used to analyze the NASA Common Research Model (CRM) in a wing-body configuration. The codes are run on structured and unstructured common grid families built specifically for the 5 th AIAA CFD Drag Prediction Workshop (DPW-5) allowing for meaningful comparison of data. There are six grid sizes in the family ranging from a 0.6 million cell “Tiny” mesh up to a 138 million cell “Super-Fine” mesh. Results from a grid convergence study are evaluated for each solver and grid type with focus on isolating individual effects of turbulence model and differencing scheme on computed forces, moments and wing pressures. A “Medium” mesh consisting of 5.1 million cells is used to run the wing-body configuration through an angle-of-attack sweep as part of a buffet onset study. The solutions are used to better understand variations in high speed wing separation prediction driven by the strengthening shock and by corner flow physics at the wing-body juncture. Numerical simulation of side-of-body separation continues to be a challenge for RANS methods where solutions are sensitive to grid density and turbulence model, amongst other variables. However, a newly developed quadratic constitutive relation (QCR) is employed with favorable results. Two additional studies are conducted to: a) investigate how well common grid solutions compare with those on a grid built using best practices for a given flow solver, and b) quantify the effects of transition and wing twist to provide additional corrections needed for comparisons of CFD results with experimental data.

A reduced dissipation approach is developed for and studied on unstructured grids using the BCFD code. The approach, termed bounded central differencing, or BCD, acts in two ways to reduce the inherent dissipation in the Roe scheme on arbitrary meshes. The proposed BCD approach blends several recent low dissipation approaches and adjusts them for a greater deal of robustness on unstructured grids of arbitrary element type. BCFD typically uses least squares cell-based gradients whose stencil involves all node neighbors. These gradients have been shown to be overly dissipative for unsteady simulations. To lessen the dissipation in the BCD approach, the component of the derivative in the edge direction is replaced with 50% of the central difference derivative based on the cell center data of the parent and face neighbor cells. Second, the Roe dissipation term is allowed to be decreased by an amount determined from the parameter fd from the Delayed Detached Eddy Simulation (DDES) method in combination with a wiggle detector and grid quality metric. This approach ensures that the simulation recovers the full Roe scheme in the RANS region, while allowing a more central-difference-like behavior far from the walls where typically it is desired to resolve eddy structures. An important distinguishing factor of the current method is its attention to regions of poor grid quality. Performance of the approach is tested in decaying isotropic turbulence for different grid resolutions and two topologies, on a NACA 0021 airfoil, and on a typical commercial aircraft flap edge where acoustics are of concern. All test cases are compared to experimental data when available. In all cases, the BCD approach delivered favorable results and was shown to be robust across many grid types/resolutions.

Simulations were used to aid in the development of a modified wedge test (MWT). This explosive sensitivity experiment allows the shockwave curvature to be defined in order to investigate the effect of combined shock-shear loading on sensitivity. Various widths of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with a linewave generator and a Detasheet booster, and the shock wave was attenuated using a slab of PMMA. In developing simulations for these three material experiments, calibrations of the PBXN-110 ignition and growth model and of the PMMA constitutive model were investigated in order to choose between several models found in the literature. A calibration shot from the MWT was also used to demonstrate the appropriateness of the models selected. Experimental results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distances predicted in CTH for the thicker donor slab compare very favorably with the actual experiments; however, for thinner donor slabs, the actual experimental results seem to suggest a more sensitive behavior than the simulations are able to capture.

The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various widths of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the shock from the donor would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor with PMMA spacers placed between the donor and the wedge sample. A high-speed electronic framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of along the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50...

Parathyroid hormone-related protein (PTHrP), a mediator of hypercalcemia of malignancy, has been detected in many tumours and in some normal foetal and adult tissues. PTHrP has potent effects on bone turnover in vivo and in vitro. In this study we cultured cells derived from expiants of bone obtained from 40 subjects (age range 2–88 years). Immunoreactive PTHrP (iPTHrP) was detected by immunoradiometric assay (IRMA) in conditioned medium from 25 of 40 cultures of bone-derived cells. PTHrP mRNA was detected in bone-derived cells by reverse transcriptase-linked polymerase chain reaction (RT-PCR). The identity of PCR products was confirmed by Southern blotting. Local production of PTHrP in vivo may be important in the regulation of bone growth and remodelling.

Facially-differentiated cholaphanes (2) were synthesized in good yields from cholic acid (1). Key steps were the selective 3,7-bis-O-acetylation of methyl cholate (3), the 12-O-benzylation of diacetate 4, and the introduction of a 3β-(p-aminomethyl)phenyl substituent using an arylmanganese reagent and employing the novel “benzostabase” N-protection methodology.

The Common Research Model utilized by the fourth Drag Prediction Workshop was employed to investigate the accuracy of three primary codes used at Boeing for transonic aerodynamic ow analysis. The codes used in this study are CFL3D (block structured), OVERFLOW (overset structured), and BCFD (unstructured). Solutions were obtained for the wing-body con guration with the horizontal tail at incidence angles of 0◦, +2◦, −2◦ and with the tail removed. Grid convergence and resolution, mesh topology, and turbulence models were considered the primary factors in this study for accurate predictions of cruise drag, pitching moments, and Reynolds number e ects. Also, these factors were considered in wing and tail side-of-body ow separation predictions. In this study, all three cases (one required and two optional) were completed with all three codes. The solutions were obtained with the one-equation turbulence model of Spalart & Allmaras and the twoequation SST turbulence model of Menter. For the trim drag and Reynolds number e ect studies (optional cases), OVERFLOW and BCFD were run only with the Spalart-Allmaras turbulence model.

To evaluate algorithmic changes in the unstructured grid ow solver BCFD, a series of basic simulations have been completed that include detailed studies of both grid size and mesh dependency for a range of di erent uid phenomena. These solutions and the di erences exhibited as a result of di erent meshes are compared to both theoretical results and experimental data. These results show that second-order accuracy is obtained for these problems and that, with adequate grid resolution, there is little sensitivity to the mesh topologies investigated for the present problems. The absence of sensitivity to mesh topology is not expected to generalize for more complicated problems.

The 3 rd AIAA Drag Prediction Workshop (DPW 3) showed a wide range of predictions using unstructured grid technology. At that time, Boeing’s BCFD unstructured flow solver lacked the accuracy of structured grid flow solvers at predicting absolute cruise drag numbers. Since the Workshop, efforts have focused on improving the accuracy of BCFD unstructured grid predictions by re-visiting the numerical discretization and paying careful attention to all aspects of the algorithm. Improvements in the cell gradient calculation, slopelimiter, viscous flux operator, and boundary conditions have lead to significant accuracy improvements. This is illustrated by updated predictions on the DLR F6 (DPW 3 configuration) where the latest simulations rival the accuracy obtained by the best industrial codes.

A new equation of motion is applied to bubbles and sand particles injected near the wall in a direct numerical simulation of a turbulent boundary layer of water. The surface-forces are considered systematically to assess their effect on particle motion, concentration, diffusion rates, and Lagrangian statistics. The results show that strong lift forces can be obtained when the particle’s terminal velocity is aligned with the freestream direction but only small effects are obtained if the terminal velocity is directed away from the wall. While finite Reynolds number effects are found to be small for the quasi-steady drag force, the choice of history force model is quite sensitive—an effect attributed to the long “memory” of the creeping flow expression. In general, the Lagrangian statistics were found to be the most sensitive output, sometimes varying largely between choice of surface-forces.Copyright © 2009 by ASME

In order to simulate the motion of bubbles, drops, and particles, it is often important to consider finite Reynolds number effects on drag, lift, torque and history force. Herein, an equation of motion is developed for spherical particles with a no-slip surface based on theoretical analysis, experimental data and surface-resolved simulations. The equation of motion is then extended to account for finite particle size. This extension is critical for particles which will have a size significantly larger than the grid cell size, particularly important for bubbles and low-density particles. The extension to finite particle size is accomplished through spatial-averaging (both volume-based and surface-based) of the continuous flow properties. This averaging is consistent with the Faxen limit for solid spheres at small Reynolds numbers and added mass and fluid stress forces at inviscid limits. The finite Rep corrections are shown to have good agreements with experiments and resolved-surface simulations. The finite size corrections are generally fourth-order accurate and an order of magnitude more accurate than point-force expressions (which neglect quadratic and higher spatial gradients) for particles with size on the order of the gradient length-scales. However, further work is needed for more quantitative assessment of the truncation terms and the overall model robustness and accuracy in complex flows.

Combined shock and shear loading of explosives has been shown to result in detonation of explosives at input pressures less than those required with a nearly planar shock. In this study, the effect of combined shock and shear loading on PBXN‐110 is investigated. The explosive sample is loaded by a TNT/Octol plane wave lens or a Pentolite pad in contact with a layer of PMMA followed by a cylindrical wave shaper that has one side angled at 45 degrees. The experiment is repeated for different thicknesses of the PMMA layer in order to vary the input pressure. In addition, the experiment is modeled using the Lagrangian finite element hydrocode EPIC, and the results of the experiments are compared with the numerical simulations.

An unstructured grid solver implemented in the BCFD code has been applied to simulate the eect of a micro-ramp on oblique shock wave/boundary layer interactions. Specifically, the micro-ramp’s ability to prevent inlet unstart was examined. The 3D Reynolds-averaged Navier-Stokes equations were solved by an implicit time-marching method. Starting from a steady-state solution at a freestream Mach number of 2.0, the upstream boundary condition was perturbed to simulate a disturbance upstream of the oblique shock wave/boundary layer interaction. The reaction of the flow field to this disturbance was examined for cases with and without a micro-ramp. The results are in agreement with the previous findings of Anderson et al.