Improvement of the aerodynamic behaviour of the passenger car by using a combine of ditch and base bleed.

The current study investigates different methods to minimize the drag coefficient (CD) without ignoring the safety factor related to the stability of a vehicle, i.e., the lift coefficient (CL). The study was carried out by employing an SUV car analyzed numerically using one of the CFD software, Ansys. Four different models such as realizable k-ε, standard k-ω, shear stress transport k-ω, and Reynolds stress model (RSM). The considered models have been validated with experimental data and found in good agreement. The considered inlet velocity varies from 28 to 40 m/s, the results showed that the drag coefficient and the stability are both improved by applying a modification on the roof of the considered car.

Improvement of the aerodynamic behavior of a sport utility vehicle numerically by using some modifications and aerodynamic devices.

The present study proposes aerodynamically optimized exterior designs of a sport utility vehicle using computational fluid dynamics analysis based on steady-state Reynolds-averaged Navier-Stokes turbulence models. To achieve an optimal design, modifications of the outer shape and adding some aerodynamic devices are investigated. This study focuses on modifying this vehicle model's upper and front parts. At the same time, the rear diffuser and spare tire on the back door as a fairing are used as aerodynamic devices for improving streamlines. All these modifications and add-on devices are simulated individually or in combination to achieve the best exterior design. A variety of Reynolds numbers are used for determining the optimization variables. Tetrahedral cells are used throughout the global domain because of the sharp edges in the geometry of the Discovery car model. At the same time, prism cells around car surfaces are adopted to improve the accuracy of the results. A good agreement between the numerical drag coefficient in the present study for the baseline models and the experimental data has been achieved. Changes in the drag and lift coefficients are calculated for all models. It is clear from the numerical results that the use of combined modifications and add-on devices has a significant effect in improving the overall aerodynamic behavior. As a result, the drag coefficient for the optimal design of the Discovery 4th generation is reduced from 0.4 to 0.352 by about 12% compared to the benchmark. Simultaneously, the lift coefficient is 0.037 for optimal design, and it is an acceptable value. It is found that combining all optimal modified configurations can improve both CD and CL simultaneously.

Chemical eye injury: pathophysiology, assessment and management.

Chemical eye injury (CEI) is an acute emergency which can threaten sight and life. These commonly occur at home or the workplace with the former being generally mild and the latter more severe and bilateral. Major workplace accidents involve other parts of the body and can be associated with inhalation or ingestion of the chemical. Alkali injuries cause damage by saponification of tissue and deeper penetration as a consequence. Acid injuries cause rapid coagulation of tissue, which impedes penetration and limits damage. Irritants such as alcohols, cause superficial epithelial denudation. Severe chemical insult can affect all anterior segment structures causing iris, pupil and lens abnormalities. Eye pressure is variably affected and can be low or high or start as one and rapidly change to the other. Chorioretinal changes in the form of vasculopathy are seen and ascribed to be secondary to anterior segment inflammation rather than due to the direct effect of CEI. Final outcome related to structure and function is determined by the injurious agent, duration of exposure, nature of treatment and the rapidity with which it is instituted. Prevention of further damage by profuse and prolonged eye wash, after ascertaining pH of both eyes, together with exploration and removal of all particulate matter, is the key. Other management principles include a complete and thorough assessment, control of inflammation, facilitation of healing and prevention and management of sequelae and complications. Intraocular pressure is often forgotten and must be assessed and managed. Management often requires a multidisciplinary approach.

Association between unilateral quiescent stromal herpetic keratitis and bilateral dry eyes.

PURPOSE: According to our clinical observation, patients with quiescent herpes simplex virus (HSV) stromal keratitis often seem to present with signs of dry eye in the contralateral eye. Our goal was to compare dry eye signs and symptoms in both eyes of patients with quiescent HSV stromal keratitis with those of age- and sex-matched control subjects with healthy corneas. METHODS: A case-control study with 24 subjects per group. RESULTS: The average age of 10 men and 14 women in each group was 58 years. The HSV eye of cases was first compared with the contralateral eye with a healthy cornea. As expected, the HSV eye had a significantly lower corneal sensation threshold (P = 0.001); no significant difference was however found for Schirmer tests done with anesthesia (basal tear secretion) and without anesthesia, tear breakup time, mucus and debris in the tear film, and eyelid margin redness or swelling. Then, the HSV eye of cases was compared with the right eye of controls, whereas the healthy eye of cases was compared with the left eye of controls. Patients with unilateral quiescent HSV stromal keratitis had significantly lower bilateral Schirmer tests both with anesthesia (P = 0.001) and without anesthesia (P = 0.02). Dry eye symptoms of the healthy cornea of cases and those of controls did not differ significantly. CONCLUSIONS: Both eyes of patients with quiescent HSV stromal keratitis in our population were dry even if many patients with HSV stromal keratitis did not have symptoms in their fellow eye.