The Effect of wake Turbulence Intensity on Transition in a Compressor Cascade

Direct numerical simulations of separating flow along a section at midspan of a low-pressure V103 compressor cascade with periodically incoming wakes were performed. By varying the strength of the wake, its influence on both boundary layer separation and bypass transition were examined. Due to the presence of small-scale three-dimensional fluctuations in the wakes, the flow along the pressure surface undergoes bypass transition. Only in the weak-wake case, the boundary layer reaches a nearly-separated state between impinging wakes. In all simulations, the flow along the suction surface was found to separate. In the simulation with the strong wakes, separation is intermittently suppressed as the periodically passing wakes managed to trigger turbulent spots upstream of the location of separation. As these turbulent spots convect downstream, they locally suppress separation. © 2014 Springer Science+Business Media Dordrecht

Convenient Synthesis of Some New Bi-heterocycles conataining 3-Aminoquinazolin-4(3H)-one and 1,2,4-Triazole moieties

Dicarboxylic acids, thiosemicarbazides and methylanthranilate reacted to give methyl-2-(3-(5-mercapto-4-s-1,2,4-triazol-3-yl)-3-oxoalkylamino)benzoates 4. The laters, cyclized with hydrazine hydrate to give 3-amino-2-((5-mercapto-4 substitued-1,2,4-triazol-3-yl)alkyl)quinazolin-4(3H)-ones 5 which expected to have biological effects

Entropy and fluctuation relations in isotropic turbulence

Based on a generalized local Kolmogorov-Hill equation expressing the evolution of kinetic energy integrated over spheres of size $\ell$ in the inertial range of fluid turbulence, we examine a possible definition of entropy and entropy generation for turbulence. Its measurement from direct numerical simulations in isotropic turbulence leads to confirmation of the validity of the fluctuation relation (FR) from non-equilibrium thermodynamics in the inertial range of turbulent flows. Specifically, the ratio of probability densities of forward and inverse cascade at scale $\ell$ is shown to follow exponential behavior with the entropy generation rate if the latter is defined by including an appropriately defined notion of ``temperature of turbulence'' proportional to the kinetic energy at scale $\ell$

Transition induced by linear and nonlinear perturbation growth in flow past a compressor blade

Flow past a NACA 65 blade at chord-based Reynolds number 138;500 is studied using stability analysis, generalised (spatially weighted) transient growth analysis and direct numerical simulations (DNS). The mechanisms of transition on various sections of the blade observed in previous work (Zaki et al. 2010) are examined, with a focus on the pressure side around the leading edge. In this region, the linearly most energetic perturbation has spanwise wavenumber 40π (five boundary layer thicknesses) and is tilted against the mean shear to take advantage of the Orr mechanism. In a DNS, the nonlinear development of this optimal perturbation induces ˄ structures, which are further stretched to hairpin vortices before breaking down to turbulence. At higher spanwise wavenumber, e.g. 120π, a free-stream optimal perturbation is obtained upstream of the leading edge, in the form of streamwise vortices. During its nonlinear evolution, this optimal perturbation tilts the mean shear and generates spanwise periodic high and low-speed streaks. Then through a nonlinear lift-up mechanism, the low-speed streaks are lifted above the high speed ones. This layout of streaks generates a mean shear with two in inflectional points, and activates secondary instabilities, namely inner and outer instabilities previously reported in the literature

The possible protective effect of L-arginine against 5-fluorouracil-induced nephrotoxicity in male albino rats

5-fluorouracil (5-FU) is a potent antineoplastic agent used for the treatment of various malignancies. The L-arginine nitric oxide (NO) pathway involved in the pathogenesis of chemotherapy induced kidney damage. This work investigated the beneficial mechanism of L-arginine supplementation in 5-FU induced nephropathy. Eighty male Wistar rats were divided into four equal groups: control group; L-arginine group (378 mg/rat/day for 4 weeks); 5-FU group (189 mg/rat/week for 4 weeks) and L-arginine for 1 week before and 4 weeks concomitant with 5-FU group. At the end of experiment, the kidney functions were assessed and kidneys specimens were processed for paraffin sections and stained with haematoxylin and eosin (H&E), Masson’s trichome (MT) and periodic acid-Schiff (PAS) stains. Other sections were processed for immunohistochemical demonstration of caspase-3 and inducible NO synthase (iNOS). Image analyser was used to analyse the results morphometrically and statistically. L-arginine administration to 5-FU treated animals elicited significant reduction in serum urea and creatinine levels, urine volume, urinary protein excretion and kidney/body weight ratio in comparison to fluorouracil treated group. L-arginine improved glomeruloscelerosis, degeneration of convoluted tubules and interstitial fibrosis in 5-FU treated animals. L-arginine attenuated effectively some biochemical and histological changes in 5-FU nephrotoxicity

Temperature influence on total volatile compounds (TVOCs) inside the car cabin of visible light transmittance

In the automotive industry indoor air quality or Vehicle Indoor Air Quality (VIAQ) are caused by various substances emitted from interior materials inside a vehicle. The volatile organic compounds (VOCs) are an example of emitted substances from the interior materials which is harmful to the human body. As stated by previous researches, there is a strong correlation between the total VOCs emission and interior temperature. This occurs due to the solar radiation through the back window glasses, windscreen and side window glasses. This trapped heat can accelerate the melting process of trim materials such as hard plastic and rubber, thus causing the emission of total VOCs (TVOCs). Therefore, reducing the percentage of visible light transmittance (VLT) will help to reduce radiation process. The aim of this study is to investigate the effect of VLT level on TVOCs emission in the vehicle cabin under static condition (parked and unventilated) and operating condition (driving and air-conditioned). For static condition the result shows that the TVOCs concentration linearly decreases whenever the percentage of VLT level decreases. However, for operating condition the percentage of VLT have less significance after 50 minutes driving time. In conclusion, the VLT levels have a strong relationship to the TVOCs concentration despite after a long driving time

Calcium Levels in Ruffle-Ended and Smooth-Ended Maturation Ameloblasts

Scanning electron microscopy was used to distinguish the topographical characteristics of two maturation ameloblast types in freeze-dried blocks of enamel organ tissue. This distinction was based primarily upon the configuration of the distal ends of the ameloblasts and the presence or absence of wide intercellular spaces. Energy dispersive x-ray spectrometry was applied to compare calcium levels in various regions of tissue identified as constituting either ruffle-ended or smooth ended ameloblasts. Greater levels of calcium were found in the distal ends of the ruffle-ended cells than in their proximal ends. In addition, greater calcium levels were found in the distal ends of the ruffle-ended cells than the distal ends of the smooth-ended cells. The higher calcium levels in ruffle-ended cells correlates with the view that these cells are actively involved in control of movement of calcium to the enamel front

Secretory Ameloblasts and Calcium Distribution During Normal and Experimentally Altered Mineralization

The distribution of calcium in relation to secretory ameloblasts of the rat incisor was studied. An experimental model system in which enamel mineralization was temporarily inhibited by injecting sodium fluoride and cobalt chloride was used. Potassium pyroantimonate (PPA) cytochemistry, electron energy loss spectroscopy (EELS), and energy dispersive X-ray spectrometry (EDS) were used to clarify the role of the ameloblast in controlling calcium distribution during normal and experimentally altered enamel mineralization. Secretory ameloblasts chemically-preserved in glutaraldehyde either with or without PPA were analyzed for calcium; those preserved with PPA showed higher concentrations of calcium than did those preserved with glutaraldehyde only. Freeze-dried control and experimental tissues showed an increasing gradient of calcium from stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were reduced near the distal ends of the cells following fluoride and cobalt injections, while magnesium levels were increased markedly in the same region. This multi-method approach showed correlated calcium localization in specific regions of this cell in relation to changes in function. The study thus provides additional evidence for active involvement of the ameloblasts in enamel mineralization

High-precision calculations of In I and Sn II atomic properties

We use all-order relativistic many-body perturbation theory to study 5s^2 nl configurations of In I and Sn II. Energies, E1-amplitudes, and hyperfine constants are calculated using all-order method, which accounts for single and double excitations of the Dirac-Fock wave functions.Comment: 10 pages, accepted to PRA; v2: Introduction changed, references adde