Numerical Investigation of Roughness Effects on Transition on Spherical Capsules.

To address the hitherto unknown mechanism of boundary-layer transition on blunt reentry capsules, the role of roughness-induced disturbance growth on a spherical-section forebody is assessed via optimal transient growth theory and direct numerical simulations (DNS). Optimal transient-growth studies have been performed for the blunt capsule experiments at Mach 5.9 in the Hypersonic Ludwieg tube Braunschweig (HLB) of the Technische Universität Braunschweig, which included measurements behind a patch of controlled, distributed micron-sized surface roughness. Transient-growth results for the HLB capsule indicate similar trends as the corresponding numerical data for a Mach 6 experiment in the Actively Controlled Expansion (ACE) facility of the Texas A&M University (TAMU) at a lower Reynolds number. Both configurations indicate a similar dependence on surface temperature ratio, and more important, rather low values of maximum energy gain. DNS are performed for the conditions of the HLB experiment to understand the generation of stationary disturbances by the roughness patch and the accompanying evolution of unsteady perturbations. However, no evidence of either modal or nonmodal disturbance growth in the wake of the roughness patch is found in the DNS data; thus, the physical mechanism underlying the observed onset of transition still remains unknown.

The Biological Metallic versus Metallic Solution in Treating Periprosthetic Femoral Fractures: Outcome Assessment.

Introduction. The periprosthetic fracture of the femur is, in order of frequency, the fourth leading cause (5.9%) of surgical revision. Our study aims to demonstrate how the grafting of bone splint betters the outcomes. Materials. We treated 15 periprosthetic femoral fractures divided into two groups: PS composed of 8 patients treated with plates and splints and PSS involving 7 patients treated only with plates. The evaluation criteria for the two groups during the clinical and radiological follow-up were the quality of life measured by the Short Form (36) Health Survey (SF-36), Harris Hip Score (HHS), Modified Cincinnati Rating System Questionnaire (MCRSQ), bone healing measured by the Radiographic Union Score (RUS), postoperative complications, and mortality. The evaluation endpoint was set at 24 months for both groups (p < 0.05). Results. The surgery lasted an average of 124.5 minutes for the PS group and 112.6 minutes for the PSS. At 24 months all clinical and radiographic scores were p < 0.05 for the PS group. During follow-up 4 patients (2 in each group) died of causes not related to surgery. Conclusions. The use of the metal plate as opposed to cortical allogenic splint should be taken into consideration as a noteworthy point for periprosthetic femoral fractures.