ANALYSIS OF FLOW STRUCTURES AROUND INCLINED BLUFF BODIES

This thesis uses numerical investigations to examine details of the turbulent flow past bluff bodies, in particular around various inclined flat plate configurations. The study consists of three phases: (1) flow past an infinitely long inclined flat plate, (2) flow past a finite length inclined flat plate near a wall and (3) flow past a stand-alone solar panel with support structure. In Phase 1, the development of three-dimensional fluid structures around an infinitely long inclined flat plate at Reynolds number of 1.57×105 is reported. The Detached Eddy Simulation (DES) is validated against well-established experimental data. The flow analysis in two-dimensional planes provides fundamental information about the spanwise and streamwise vortices that develop near the body and in its wake, but offers limited information on the formation and evolution of these vortices. Using the λ2-criterion to visualize the three-dimensional fluid structures, the interaction between the spanwise and streamwise vortical structures and the shear layers is discussed. It is found that the spanwise wavelength of the streamwise vortical structures lie in the range corresponding to the mode B instability reported in previous studies of wake transition. The effect of a wall on the flow structures around a finite length inclined flat plate at two proximities from the wall is investigated in Phase 2. In the mean analysis, it is found that the small clearance produces a wall-jet like flow in the gap which elongates the wake region, whereas a strong upwash is captured for the larger gap, reducing the length of the wake. Transient three-dimensional flow structures are captured using the λ2-criterion. The early stage development of the flow around the plate shows inverted hairpin-like vortices that generate a counter-rotating sheared vortex and a pair of vertical vortex tubes extending from the wall. This pair of vortex tubes is considered as the source of the meandering structures reported in the literature. At the later flow development stage, an asymmetric distorted flow for the smaller gap is observed, whereas there is a nearly symmetric wake pattern for the larger gap. Numerical investigation of flow past a stand-alone solar panel with a supporting post is conducted using DES in Phase 3. Two elevations of the solar panel are examined. Mean velocity profiles and two-dimensional mean vorticity contours do not illustrate significant changes in the flow patterns, except for relatively weak vortices that develop along the post. The transient three-dimensional analysis using the λ2-criterion captures four unique fluid structures around the body for the small gap case. On the other hand, the large gap case shows minimum influence from the post except for ligaments of vortex tubes that extend from the post. The same vortex structures also develop in the small gap case but are merged into the large scale vortices in the wake

NUMERICAL SIMULATION OF FUEL SPRAYS IN DIESEL ENGINES

Engine simulations with diesel fuel spray at ultra-high injection pressures ranging from 100 to 300 MPa were conducted in a vertical valve engine geometry using ANSYS FLUENT 13.0. The in-cylinder flow was calculated by RANS models and DES and validated with the experimental data. The fuel spray characteristics such as Sauter mean diameter, spray cone angle, spray tip penetration and fuel/air mixture were studied under the presence of in-cylinder flow. The ultra-high injection pressures assist in the breakup of droplets into smaller size, accelerating atomization, dispersing the spray in a wide cone angle and mixing air/fuel effectively. However, the rate of change in droplet size was reduced by increasing the injection pressure. Also, high air density in the cylinder did not induce the breakup of droplets. The spray simulations failed for the RNG k-epsilon and standard k-omega models and the issue was found to be the sensitivity to of the calculations to grid size and type in the particle tracking methodology

BRAKING FORCES DURING BICYCLE PEDALING: AN EXAMINATION OF THE FULL CRANK ROTATION

Pedalling skills are evaluated using angular impluse of negative crank torque (INCT) that occurs in pulling phase (180-360° of crank rotation that 0° is top dead center. INCT has the effect of inhibit crank rotation (“braking force“). The aim of study was to obtain findings to reduce INCT for improving cyclists\u27 pedalling skills. We examined the relationship between INCT and kinetic pedalling data through the full crank rotation. Fifteen male cyclists performed constant pedalling at 80%Vo2max and 90rpm. Kinetic and kinematic pedalling data were measured by the pedal-shaped force platform (KISTLER) and by a 3D motion capture system (VICON). A negative correlation was indicated 80-250° of crank rotation between horizontal pedal force (Fh) and INCT (pNCT occurring in pulling phase was affected by amount of Fh in pushing phase

FACILE AND SENSITIVE HPLC-UV METHOD FOR DETERMINATION OF NINTEDANIB IN RAT PLASMA

Objective: In this study, a facile and sensitive high-performance liquid chromatographic method for determination of nintedanib in rat plasma was developed and validated.Methods: After plasma protein was precipitated by addition of acetonitrile, the supernatant underwent centrifugation. An aliquot was then injected into a high-performance liquid chromatographic system with a Mightysil RP-18 GP II ODS column (250 × 3.0 mm, length by inner diameter, 5-μm particle size) maintained at 50 °C. A mobile phase mixture of 20 mmol phosphate buffer (pH 3.0) and acetonitrile (7:3, v/v) was used at a flow rate of 0.6 mL/min, with UV detection at a wavelength of 390 nm for isocratic separation and detection of nintedanib, its main metabolite (BIBF1202), and p-nitrophenol as an internal standard.Results: The quantitative range of nintedanib concentration in this method was 12.5–400 ng/ml, and the calibration curves were linear. The intra-and inter-day accuracy values (relative errors) were in the range of −3.65%–4.00% and −3.65%–3.64%, respectively. The intra-and inter-day precision values (relative standard deviations) were<5.9% and 8.36%, respectively. The method was successfully applied to a pharmacokinetic analysis of nintedanib in rats after intravenous administration.Conclusion: In this study, a rapid, sensitive, and simple HPLC-UV method for the quantitation of nintedanib in rat plasma was developed and validated. The method was shown to be accurate and precise and was successfully applied to a pharmacokinetic study

Heat-not-burn cigarettes induce fulminant acute eosinophilic pneumonia requiring extracorporeal membrane oxygenation

Background Although the cause of acute eosinophilic pneumonia (AEP) has not yet been fully clarified, cigarette smoking is reported to be a risk factor for developing AEP. The heat-not-burn cigarette (HNBC) was developed to reduce the adverse effects of smoke on the user's surroundings. However, the health risks associated with HNBCs have not yet been clarified. We report a successfully treated case of fatal AEP presumably induced by HNBC use. Presentation of case A 16-year-old man commenced HNBC smoking two weeks before admission and subsequently suffered from shortness of breath that gradually worsened. The patient was transferred to emergency department and immediately intubated because of respiratory failure. Computed tomography showed mosaic ground-glass shadows on the distal side of both lungs with a PaO2/FIO2 ratio of 76. The patient required veno-venous extracorporeal membrane oxygenation (ECMO) for severe respiratory failure. He was diagnosed with AEP by clinical course and detection of eosinophils in sputum; thus, methylprednisolone was administrated. The patient was weaned off ECMO four days after initiation and extubated the day after. He fully recovered without sequelae. Conclusion As far as we know, our patient is the first case of AEP induced by HNBC use successfully treated with ECMO. Emergency physicians must be aware that HNBCs can induce fatal AEP

Effect of tricyclic drugs on mitochondrial membrane.

The effects of tricyclic drugs (clomipramine, imipramine, chlorpromazine and promethazine) on isolated liver mitochondria of rats were examined. All the drugs tested accelerated state 4 respiration. Their stimulative potency at concentrations below 100 microM was in the order of chlorpromazine greater than clomipramine greater than imipramine, promethazine. On state 3 respiration, the chlorine containing drugs had an inhibitive effect at high concentrations, while the other drugs seemed to have a slightly stimulative effect. These drugs stimulated latent ATPase activity of mitochondria. Clomipramine and chlorpromazine inhibited 2, 4-dinitrophenol-stimulated ATPase activity in a dose-dependent fashion. Imipramine also inhibited 2, 4-dinitrophenol-stimulated ATPase activity at high concentrations. Promethazine, however, had almost no effect. All the drugs induced potassium release from mitochondrial vesicles, and their potency was in the order of clomipramine greater than chlorpromazine greater than imipramine greater than promethazine. These results suggest that clomipramine, imipramine, chlorpromazine and promethazine cause impediments in both mitochondrial respiration and ion compartmentation, and that the chlorine containing drugs are more toxic than others on the functions of the mitochondrial membrane.</p

Effects of aggregation on methamphetamine toxicity in mice.

Methamphetamine (MA) toxicity in aggregated mice was studied by varying the number of mice and the proportion of MA treated mice kept in the same confined space. The lethality was measured 24 h after intraperitoneal injections of MA at doses ranging from 10 to 100 mg/kg. MA lethality, over a wide dose range (15 to 50 mg/kg), was higher in aggregated mice than in those maintained in isolation. The greater the proportion of MA-treated mice in aggregation was, the higher the MA lethality was. In aggregations of 10 mice, MA was lethal at lower doses than in aggregations of 5 mice. These results indicate that the lethality of MA is influenced by confinement and aggregation.</p

In vitro release of tegafur from a fatty-base suppository and in vivo bioavailability of tegafur.

This study was designed to determine the in vitro release of tegafur from a suppository and the in vivo bioavailability of tegafur in rats. Two different suppository preparations (product A-1 and product A-2) containing 750 mg of tegafur were tested for in vitro release of tegafur by the Muranishi Method (membrane diffusion method) and the partially modified paddle method (permeability through dialysis tubing). When determined by either method, the amount of tegafur released from product A-2 during the whole experimental period was significantly greater than that released from product A-1. When tested by the Muranishi method, however, the difference in the amount released during the first 10-min period was not significant. A greater bioavailability of tegafur after rectal administration was obtained by product A-2 more than product A-1. A significant correlation was observed between the in vitro release and the in vivo bioavailability. The present results indicate that there are considerable differences in physiochemical characteristics between product A-1 and product A-2.</p