A two-dimensional computational study had been performed regarding aerodynamic forces and pressures affecting a cambered inverted airfoil, CLARK-Y smoothed with ground effects by solving the Reynolds-averaged Navier-Stokes equations, using the commercial software COMSOL Multiphysics 5.0 solver. Turbulence effects are modeled using the Menter shear-stress transport (SST) two-equation model. The negative lift (down-force), drag forces and pressures surface were predicted through the simulation of wings over inverted wings in different parameters namely; varying incidences i.e. angles of attack of the airfoils, varying the ride hide from the ground covering various force regions, two-dimensional cross-section of the inverted front wings to be fixed on nose of a race car- and varying speeds of initial airflow (Reynolds number). The results show that the down-force increases as the angle of attack increases; however, if an inverted wing is fixed on a car at high angles of attack the wing starts to stall which is not a desired condition that affects the vehicle stability and performance. As the ride height was reduced, the down-force was increased; at clearances between the suction surface and the ground of less than 0.2 of the chord length c, the down-force is significantly higher. Very close to the ground, at a ride height of less than 0.1c, down-force decreases as the wing stalls. Also, down-force increases as the free-stream velocity (Reynolds number) increases. The pressures for lower and upper surface of the wing increased with increasing both of angle of attack and ride height, but remains relatively ineffective with varying the speeds.
Abstract
The current study presents numerical investigation of the fluid (air) flow characteristics and convection heat transfer around different corrugated surfaces geometry in the low Reynolds number region (Re<1000). The geometries are included wavy, triangle, and rectangular. The effect of different geometry parameters such as aspect ratio and number of cycles per unit length on flow field characteristics and heat transfer was estimated and compared with each other. The computerized fluid dynamics package (ANSYS 14) is used to simulate the flow field and heat transfer, solve the governing equations, and extract the results. It is found that the turbulence intensity for rectangular extended surface was larg
... Show MoreObjectives Dental implant is a revolution in dentistry; some shortages are still a focus of research. This study use long duration of radiofrequency (RF)–magnetron sputtering to coat titanium (Ti) implant with hydroxyapatite (HA) to obtain a uniform, strongly adhered in a few micrometers in thickness. Materials and Methods Two types of substrates, discs and root form cylinders were prepared using a grade 1 commercially pure (CP) Ti rod. A RF–magnetron sputtering device was used to coat specimens with HA. Magnetron sputtering was set at 150 W for 22 hours at 100°C under continuous argon gas flow and substrate rotation at 10 rpm. Coat properties were evaluated via field emission scanning electron microscopy (FESEM), scanning electro
... Show MoreBackground: The effect of garlic extracton fungal
growth and keratinolytic activity was studied in
Trichophytonmentagrophytes as one of the major
etiologic agents of human and animal dermatophytosis
in Baghdad and other parts of the World.
Objective: To investigated an alternative
antidermatophyte with minimum side effects which is
plant based and biodegradable natural product
Methods: Culture conditions for 30 isolates of T.
mentagrophytes isolated from human dermatophytosis
from both sexes with ages of 5-63 years in Central
Medical city for the period July 2009 to October 2009
were cultured on specific solid medium.
Results: The aqueous extract of garlic at various
concentrations inhibited the
Most of the mosques in the Islamic world fall under specific and known forms and patterns to a large extent, and such patterns have grown and evolved from the few basic and uniform models, but they changed slowly due to the impact with a mixture of changing functional requirements and cultural landscapes because of the variables of time and place to form patterns known and famous in this day across parts of the Islamic world and its borders. There was no exception to these patterns, but small numbers of mosques that were probably the result of personal experiences or improvisational resolutions, or in response to specific or temporary stimuli. However, the emergence of a specific pattern which does not belong to any of these patt
... Show MoreThis paper presents the Taguchi approach for optimization of hardness for shape memory alloy (Cu-Al-Ni) . The influence of powder metallurgy parameters on hardness has been investigated. Taguchi technique and ANOVA were used for analysis. Nine experimental runs based on Taguchi’s L9 orthogonal array were performed (OA),for two parameters was study (Pressure and sintering temperature) for three different levels (300 ,500 and 700) MPa ,(700 ,800 and 900)oC respectively . Main effect, signal-to-noise (S/N) ratio was study, and analysis of variance (ANOVA) using to investigate the micro-hardness characteristics of the shape memory alloy .after application the result of study shown the hei
... Show MoreAbstract:In this paper, some probability characteristics functions (moments, variances,convariance, and spectral density functions) are found depending upon the smallestvariance of the solution of some stochastic Fredholm integral equation contains as aknown function, the sine wave function
This study includes adding chemicals to gypseous soil to improve its collapse characteristics. The collapse behavior of gypseous soil brought from the north of Iraq (Salah El-Deen governorate) with a gypsum content of 59% was investigated using five types of additions (cement dust, powder sodium meta-silicate, powder activated carbon, sodium silicate solution, and granular activated carbon). The soil was mixed by weight with cement dust (10, 20, and 30%), powder sodium meta-silicate (6%), powder activated carbon (10%), sodium silicate solution (3, 6, and 9%), and granular activated carbon (5, 10, and 15%). The collapse potential is reduced by 86, 71, 43, 37, and 35% when 30% cement dust, 6% powder sodium meta-silicate, 10% powder activated
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