Physics Based Washing Machine Simulations.

This thesis describes the development of a simulation of the interaction of cloth and water that takes place inside a washing machine. The simulation consists of four basic parts: a large deformation elastic thin plate model for the cloth based on Love (1944), a rectangular-Cartesian-mesh solver for the Navier-Stokes equations based on Brown et al. (2001), the Immersed Boundary method of Peskin (1972) for cloth/fluid interaction, and a domain-mapping technique for representing irregular domain boundaries on Cartesian grids. Although the lack of an accompanying experimental effort prevented its thorough validation, the final simulation was subjected to a variety of validation tests involving analytical solutions and experimental measurements in simple geometries. The implementation of the thin plate model combined with the Immersed Boundary method was able to match the natural frequencies of a vibrating plate within +/- 1%, and was able to predict large deformation beam shapes with similar accuracy. In addition, this validation effort suggests that the ratio between the Immersed Boundary method’s Lagrangian and Eulerian point-spacings should be approximately unity for better accuracy, when accounting for finite bending stiffness. Furthermore, it was found that the Immersed Boundary method formulation may provide better results with a narrow desingularization of the two-dimensional cloth onto the three-dimensional Cartesian mesh while sacrificing numerical stability. Complicated moving boundaries are handled by a domain-mapping technique that uses a Heaviside function to switch between solving the equations for the cloth/fluid mixture and specifying the velocity field for the washing machine’s solid boundaries. This boundary-condition formulation was benchmarked against well-known steady and unsteady flow fields: circular Couette flow, and a uniform flow past a cylinder. Using these individually verified basic components together, two and three-dimensional simulations of the washing machine processes are created. A selection of studies involving the effect of different numerical and physical parameters on the kinematics of cloth motion and the statistics of the cloth stresses in a vertical-axis washing machine are reported. In particular, the coarse grid simulations predicted a realistic and qualitatively correct pattern for the motion of the cloth pieces.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/57704/2/dakcabay_1.pd

Cavity induced vibration of flexible hydrofoils

The objective of this work is to investigate the influence of cavity-induced vibrations on the dynamic response and stability of a NACA66 hydrofoil at 8° angle of attack at Re=750 000 via combined experimental measurements and numerical simulations. The rectangular, cantilevered hydrofoil is assumed to be rigid in the chordwise direction, while the spanwise bending and twisting deformations are represented using a two-degrees-of-freedom structural model. The multiphase flow is modeled with an incompressible, unsteady Reynolds Averaged Navier–Stokes solver with the k–ω Shear Stress Transport (SST) turbulence closure model, while the phase evolutions are modeled with a mass-transport equation based cavitation model. The numerical predictions are compared with experimental measurements across a range of cavitation numbers for a rigid and a flexible hydrofoil with the same undeformed geometries. The results showed that foil flexibility can lead to: (1) focusing – locking – of the frequency content of the vibrations to the nearest sub-harmonics of the foil׳s wetted natural frequencies, and (2) broadening of the frequency content of the vibrations in the unstable cavitation regime, where amplifications are observed in the sub-harmonics of the foil natural frequencies. Cavitation was also observed to cause frequency modulation, as the fluid density, and hence fluid induced (inertial, damping, and disturbing) forces fluctuated with unsteady cavitation.The authors gratefully acknowledge Ms. Kelly Cooper (program manager) and the Office of Naval Research (ONR), for their financial support through Grant nos. N00014-11-1-0833 and N0014-12-C-0585, as well as ONR Global and Dr. Woei-Min Lin (program manager) through grant no. N62909-12-1-7076

Perinatal outcomes of the antenatally diagnosed omphalocele cases: a single tertiary center experience

Objectives: To evaluate the perinatal outcomes of antenatally diagnosed omphalocele cases. Material and methods: This was a retrospective study conducted between July 2014 and February 2020 at the prenatal diagnosis center of a university clinic. Gestational week of diagnosis, associated anomalies, karyotype analysis results, complications during pregnancy, termination/delivery characteristics, and postnatal results were evaluated. Results: The analysis was performed on 58 patients. The median diagnosis time was 14.5 weeks of gestation. Thirty-three cases (57%) were defined in the first trimester. 33 (57%) of 58 patients had one or more concomitant anomalies, while 25 patients (43%) had isolated omphalocele. The most common associated anomaly was a cardiac anomaly which was observed in 17 fetuses (30% of all omphalocele cases). Karyotype analysis was performed in forty-five patients (41 in the prenatal period, 4 in the postnatal period). A normal karyotype was detected in 27 cases (60%). Trisomy 18 was the most common chromosomal anomaly (n = 15, 33.3%). Thirty of 58 patients (52%) requested termination of pregnancy (TOP) in the early pregnancy period. Thirteen of the cases died in-utero (22%). Fifteen pregnancies resulted in live births (26%), of those eight were lost in the first year of life (six of them had additional anomalies, while two of them had isolated omphalocele but the omphalocele pouch was containing the liver in those two babies). Conclusions: Most of the cases with an omphalocele can be diagnosed in the first trimester. Cardiac anomalies were the most common associated anomalies, while trisomy 18 is the most common chromosomal anomaly. Thus, earlier and effective counseling can be made about the prognosis of pregnancy

Tramadol vs dexmedetomidine for emergence agitation control in pediatric patients undergoing adenotonsillectomy with sevoflurane anesthesia: prospective randomized controlled clinical study

Background: This study was designed to compare the efficacy of an intraoperative single dose administration of tramadol and dexmedetomidine on hemodynamics and postoperative recovery profile including pain, sedation, emerge reactions in pediatric patients undergoing adenotonsillectomy with sevoflurane anesthesia. Methods: Seventy-seven patient, aged 2-12, undergoing adenotonsillectomy with sevoflurane anesthesia was enrolled in this study. Patients were randomly assigned to receive either intravenous 2 mg/kg tramadol (Group T; n = 39) or 1 mu g/kg dexmedetomidine (Group D; n = 38) after intubation. Heart rates (HR), mean arterial pressure (MAP) were recorded before induction, at induction and every 5 min after induction. Observational pain scores (OPS), pediatric anesthesia emergence delirium (PAED) scores, percentage of patients with OPS = 4 or PAED scale items 4 or 5 with an intensity of 3 or 4, and Ramsay sedation scores (RSS) were recorded on arrival to the postoperative care unit (PACU) and at 5, 10, 15, 30, 45, 60 min. Extubation time and time to reach Alderete score > 9 were recorded. Results: Dexmedetomidine significantly decreased the HR and MAP 10 and 15 min after induction; increased the RSS 15, 30 and 45 min after arrival to PACU. OPS and PAED scores and percentage of patients with OPS = 4 or PAED scale items 4 or 5 with an intensity of 3 or 4 in both groups did not show any significant difference. Extubation time and time to have Alderete score > 9 was significantly longer in Group D. Conclusion: Both tramadol and dexmedetomidine were effective for controlling pain and emergence agitation. When compared with tramadol intraoperative hypotension, bradycardia and prolonged sedation were problems related with dexmedetomidine administration

Comparison of the efficacy of propofol and metoclopramide in preventing postoperative nausea and vomiting after middle ear surgery

Arslan, Mustafa/0000-0003-4882-5063WOS: 000269349300007PubMed: 19526159Objectives: To compare the administration of sub hypnotic dose of propofol with metoclopramide and placebo in prevention of postoperative nausea and vomiting (PONV) after middle ear surgery. Methods: This clinical research was performed in the Faculty of Medicine, Gazi University, Besevler, Ankara, Turkey, between December 2004 and October 2005. Following approval by the hospital ethics committee, 60 adult patients scheduled for a middle ear operation were randomly assigned into 3 groups. The patients in group P received 0.5 mg.kg(-1) propofol; in group M, 0.2 mg.kg(-1) metoclopramide, and in group C, 0.9% saline solution. The number of patients suffering from nausea and vomiting at 0-4, 4-12, and 12-24 hours postoperatively, and additional use of antiemetics was recorded. Results: Comparison of the data showed that at 0-4th hours, the incidence of vomiting was 25% in group P, 40% in group M, and 75% in group C. The incidence rate of group P was significantly lower than that of group C (p=0.002), and the rate of antiemetics use in group C was higher than that in group P (p=0.028). The Nausea Vomiting Scale scores of group C were also significantly higher than those of group P (P=0.005). There were no significant differences between the values at 4-12 and 12-24 hours. Conclusion: The administration of a sub hypnotic dose of propofol at the end of surgery was found to be at least as effective as metoclopramide in preventing PONV in the early postoperative period in adult patients undergoing middle ear surgery

Prenatal diagnosis of persistent left superior vena cava: a retrospective study of associated congenital anomalies

WOS: 000462504300004PubMed ID: 31019836Objective: To evaluate persistent left superior vena cava (PLSVC) cases according to associated cardiac, extracardiac, and chromosomal anomalies in the prenatal period and to review their outcomes. Materials and Methods: The data of patients with a prenatal diagnosis of PLSVC between January 2013 and December 2017 were reviewed retrospectively. Results: Data of 32 cases were reviewed. Nineteen (60%) cases were associated with cardiac defects, 5 (15%) were associated with both cardiac and extracardiac defects, and 8 (25%) had no associated anomalies. Two fetuses had karyotype anomalies. All patients with isolated PLSVC survived. Among the cases associated with extracardiac anomalies, cardiac anomalies, and with both extracardiac and cardiac anomalies, the survival rate was 40%, 40%, and 25%, respectively. Outcome was more favorable in cases with isolated PLSVC (100% vs. 40%). Conclusion: Prenatally diagnosed PLSVC is associated with cardiac and extracardiac anomalies in the majority of cases. The prognosis is good in isolated cases, but worsens when accompanied by cardiac or extracardiac anomalies