Three-dimensional numerical study of jet-in-crossflow characteristics at low Reynolds number

A numerical study of a square jet in a cross flow is carried out at a Reynolds number of 100. The flow field and heat transfer characteristic downstream of the jet have been explored by solving three-dimensional unsteady Navier–Stokes equations and energy equation using higher order spatial and temporal discretization. The projection of vortical structure on a plane is seen to give the component of vortex normal to the plane. Four combinations of velocity profile namely (1) uniform crossflow and uniform jet, (2) laminar boundary layer crossflow and uniform jet, (3) uniform crossflow and parabolic jet profile, and (4) laminar boundary layer crossflow and parabolic jet are compared at same phase to see their effect on the flow field and heat transfer characteristic. All the four cases are seen to exhibit unsteadiness but the jet with parabolic profile is seen to show stronger unsteadiness. The instantaneous vortical structures of all the cases at the same phase show that the structures are more complex for the jet with parabolic velocity profile. The temperature field is seen to be correlated with the vortical structures. Comparison of the time averaged flow field reveals that the jet penetration is the highest for the jet having parabolic profile and boundary layer crossflow. The adiabatic effectiveness is observed to be more for the jet with uniform velocity profile and uniform crossflow and was least for the jet with parabolic velocity profile and boundary layer crossflow.     

Effect of Gravity on Collective Excitations of a Quasi Two-Dimensional Bose Einstein Condensate in an Anharmonic Trap

Using variational method, the wave function of a quasi two-dimensionalBose-Einstein Condensate in an anharmonic trap is analyzed and the influence of gravity on the collective excitations is studied. It is found that the effect of gravity on the condensate has got crucial dependence on the anharmonicity of the trap.     

XtalFluor‐E: An Efficient Reagent for Synthesis of Oxazolines from Carboxylic Acids and O‐Silylated Amino Alcohols

An efficient protocol has been developed for the synthesis of 2‐oxazolines from carboxylic acids and silylated amino alcohols. The advantage of this method was demonstrated by preparing O‐silylated amino alcohols. The reaction proceeds via in situ desilylation of O‐silylated amide followed by cyclization. Studies on silyl deprotection were carried out to explain yield for 2‐oxazolines.     

Metal free synthesis of 1‐azaspiro[4.4]nonane‐3‐one system via reactions of nitrones with 1,1‐disubstituted allenes

In the cycloaddition reaction between fluorenone N‐aryl nitrones and 1,1‐disubstituted allenes, the initially formed cycloadduct underwent facile [1,3] shift to give 1′‐phenylspiro[fluorene‐9,2′‐pyrrolidin]‐4′‐ones. Although 1′‐phenylspiro[fluorene‐9,2′‐pyrrolidin]‐4′‐ones are stable in solid state, a few of them underwent facile aerial oxidation in solution to give the corresponding 1′‐phenylspiro[fluorene‐9,2′‐pyrrolidine]‐4′,5′‐diones in excellent overall yields.     

Microwave assisted one pot synthesis of 2-ethylamino benzimidazole,benzoxazole and benzothiazole derivatives

A rapid and efficient one-pot method for the synthesis of 2-ethylamino benzimidazole, benzoxazole, and benzothiazole derivatives has been described. The reaction of o-phenylenediamines or o-aminophenols or 2-mercaptoanilines with EDC.HCl under microwave irradiation afforded the corresponding 2-ethylamino benzimidazole, benzoxazole and benzothiazole derivatives in excellent yields.     

An alternative total synthesis of Patulolide A

A new total synthesis of [R]‐Patulolide A from readily available (R)‐propylene epoxide obtained using the asymmetric synthetic approach is reported. The key reactions involved are ozonolysis and Yamaguchi macrolactonization, resulting in the ring system.     

A distributed feedback dye laser based on higher order Bragg scattering

A distributed feedback dye laser based on second order Bragg scattering due to a sinusoidal susceptibility modulation is reported. Rhodamine 6G dye solution in three different solvents; methanol, ethanol and benzyl alcohol is pumped by interference fringes produced by two beams from the second harmonic of Nd:YAG laser. Output power is plotted as a function of the pump power. The spectrum of dye laser shows a new type of modulation.     

Dielectric and Electrical Properties of InSe Films

The dielectric and electrical properties of sandwiched Al InSe Al structures of different thicknesses are investigated. For all the thicknesses the capacitance and tan δ decrease with increase in frequency. The I-V characteristics of Al-InSe-Al structures have been studied for different thicknesses. These curves exhibit three regions ohmic, non-ohmic and breakdown regions. Optical micrographs of breakdown patterns at different stages have been taken and the results are discussed.     

Surfactant tuned morphology of mesoporous β-Co(OH)2/CMC nanoflakes: a prospective candidate for supercapacitors

Journal of Solid State Electrochemistry - Innovative electrode materials are the need of the hour towards the fabrication of electrochemical energy storage systems with superior performance. In the...