Airflow Sciences (United States)

Background: Autologous costal cartilage (ACC) and irradiated homologous costal cartilage (IHCC) are commonly used in septorhinoplasty when there is insufficient septal cartilage for grafting. Objective: To assess the surgical outcomes of patients who underwent septorhinoplasty with either ACC or IHCC as measured by rates of infection, resorption, warping, and revision rate. Methods: A retrospective analysis of patients who underwent rhinoplasty with ACC or IHCC at a single academic institution was performed. Demographic data, surgical details, antibiotic use, and outcomes, including surgical duration, infection, resorption, warping, and revision rate, were analyzed using Fisher's exact test, chi-squared test, and logistic regression. Results: One hundred forty-three patients were identified. The median age was 48 years (interquartile range: 35-57.5) and 62.2% (n = 89) were female, 61 patients (42.7%) underwent ACC, and 82 (57.3%) IHCC. Revision rate in both groups was similar (ACC = 14.8%, IHCC = 14.6%; p = 0.98). There was no difference in infection rate (ACC = 4.9%, IHCC = 3.7%; p = 0.71). Postoperative deformity and nasal obstruction were the most common indications for revision surgery. Surgical time was shorter with IHCC (p < 0.01). Mean follow-up time was 26.5 months (±25) for ACC, and 16 months (±12) for IHCC. Conclusions: ACC and IHCC are similar in terms of effectiveness and safety in septorhinoplasty.

Abstract Experimentally derived surface heat flux rate data and computational fluid dynamics (CFD) software are helping researchers more accurately simulate liquid quenching processes. This article describes an approach where surface heat flux rates are determined experimentally in a precisely controlled flow boiling test system. This data is then used to build CFD models that are proving to be quite accurate in quenching process simulations.

Abstract Three dimensional numerical models have been developed to simulate almost all steps in the thermal processing of metals with the notable exception of the quenching operation. There, the surface heat flux rates are frequently based on limited experimental thermocouple data and inverse generated heat flux rates, or general correlations for similar shapes. CFD tools provide an efficient framework for the analysis of heat flux rates in actual industrial quenching situations, though most Computational Fluid Dynamics (CFD) codes lack an appropriate boiling heat transfer model. Using data generated in a continuous quench facility, a new set of boiling heat transfer approximations are being developed that will provide the required accuracy for use as a predictive tool while being computationally efficient enough for application to industrial heat treating applications. An overview of the algorithm is presented along with an update on the model development.

The orientation in which parts are held during the quenching operation can have a strong effect on the overall success of heat treating. Certain orientations can result in significantly greater distortion than other orientations, even when high-quality quenchants are used. In this study, various simple, rolled ring geometries are examined at two different orientations to quenchant flow using computational fluid dynamics with the software program AZORE®. These parts were examined singly without the influence of other parts in close proximity. Three rolled ring geometries were examined, using the same outside diameter, while the inside diameter was varied. These flow fields will be used for understanding the likely distortion occurring during quenching.

In foundation designs, standard penetration test (SPT) blow counts are typically used to estimate shear strength properties of soils. Few correlations are widely in use to make such estimations. However, the selection of these correlation equations are not often justified or explained. This manuscript describes a new approach to estimate the shear strength properties based on the SPT blow counts. The proposed method treats SPT analogous to driving a miniature open-ended pipe pile. During SPT, part of the energy is transferred into the soil. This energy is dissipated at the soil-sampler interface to overcome skin and point resistance to penetrate a sampler into the soil. Energy balance was used to correlate the SPT blow count to the shear strength properties of the soil at the depth of testing. Two separate equations were derived: one to estimate the friction angle (ϕ′) of sand and the other to estimate the undrained shear strength (cu) of clay. SPT results from two sites were used to calibrate the proposed equations, and then two other sets of data were used to verify them. With a low average standard deviation in the calibration process, the proposed N60−ϕ′ equation demonstrated a strong correlation. The proposed N60−cu equation did not provide as strong a correlation as the N60−ϕ′ equation. However, a statistical analysis revealed that for the data used in this research, both equations could estimate shear strength properties better than the commonly used, other existing correlations. The proposed equations may not work in very stiff clay or very dense sand and should not be used to analyze SPT results with poor recovery.