Entropy generation and induced magnetic field in pseudoplastic nanofluid flow near a stagnant point

In this present article the entropy generation, induced magnetic field, and mixed convection stagnant point flow of pseudoplastic nano liquid over an elastic surface is investigated. The Buongiorno model is employed in modeling. Through the use of the boundary layer idea, flow equations are transformed from compact to component form. The system of equations is solved numerically. The Induced magnetic spectrum falls near the boundary and grows further away as the reciprocal of the magnetic Prandtl number improves. The fluctuation of induced magnetic rises while expanding the values of mixed convection, thermophoresis, and magnetic parameters, whereas it declines for increment in the Brownian and stretching parameters. The velocity amplitude ascends and temperature descends for the rise in magnetic parameter. The mass transfer patterns degrade for the higher amount of buoyancy ratio while it boosts by the magnification of mixed convection and stretching parameters. Streamlines behavior is also taken into account against the different amounts of mixed convection and magnetic parameters. The pseudoplastic nanofluids are applicable in all electronic devices for increasing the heating or cooling rate in them. Further, pseudoplastic nanofluids are also applicable in reducing skin friction coefficient.

ROLE OF NGOs IN THE PROMOTION OF AGRICULTURE

Despite the fact that agriculture sector is characterized by ‘the biggest’ sector contributing to the 18% of GDP and providing employment to more than 50% of the population, it’s also characterized by the one with hurdles that may land the sector to a stagnant point and largely affect the entire economy. This study throws light on the gaps in the agriculture sector and the role of NGOs in bridging those gaps, promoting awareness programs and upgrading development facilities. However, the government has been promising to come over all the issues that hurdle the development, but the efforts on its part have not been up to the mark. Meanwhile, NGOs are emerging as a new impetus and shouldering the agricultural development. NGOs as a third sector institutional framework have a bigger role to play in providing a strong and stout support system while ensuring effective implementation of govt. programs towards the sustainable development in various sectors such as education, poverty alleviation, health, agriculture, youth empowerment and community development. Also, this study aims at providing suggestions to effectively utilize the network of NGOs towards upliftment of agriculture sector.

Experimental investigation of the icing scaling test method for a rotating cone

One of the reliable methods of studying engine icing is to carry out testing in an icing wind tunnel. Due to the operational limitations of test facility, model-size scaling is adopted. An icing scaling test method for the rotating cone is established based on the dimensional analysis coupled with similarity theory and evaluated by considering the rotating effect. Similarity parameters are determined in the following five aspects: flow field similarity, droplet trajectory similarity, water catch similarity, heat balance similarity, and rotating characteristics similarity. Experimental icing tests have been performed at rime and glaze ice conditions to evaluate the scaling method in a closed-loop icing wind tunnel. Results show that the maximum error between the reference and scale ice shapes occurs at the stagnant point. On the areas apart from this, there is a significantly smaller error. Hence, the scaling test method is proven to be effective and reliable and can provide a theoretical basis for parameter selection of the ice wind tunnel tests.

Systematic study of methanol addition to enhance the film development of APCVD tin oxide

ABSTRACTUndoped tin oxide (SnO2) thin films have been deposited in a stagnant point flow chemical vapor deposition reactor. By adding methanol during the deposition process ten times more conductive SnO2 films are obtained, with remarkably high mobility values of up to 55 cm2/Vs. The investigations on the morphological and structural properties indicate that the main effect of methanol is the densification of the SnO2 films, which probably causes the improvement in the electrical properties. In all conditions the nucleation and coalescence phases take place very early in the growth. The films are already very conductive at a thickness below 10 nm, which is very beneficial to applications that have strict requirements in terms of film transparency. This high conductivity was attributed to a high carrier concentration, obtained without intentional doping.

Experimental Study on Temperature Fluctuation Phenomena in a Closed Branch Pipe Connecting to High Velocity and High Temperature Flow in a Main Pipe

Flow structures and temperature fluctuations in a closed branch pipe connected to a high velocity and high temperature flow in a main pipe were investigated experimentally. A straight pipe and a pipe with a bend were tested for uniform and non-uniform temperature conditions. Visualization of the flow patterns, measurement of the flow velocity and measurement of the liquid and wall temperature distributions were conducted. The flow pattern near the stagnant point in the branch pipe was a spiral flow. The time averaged velocity distributions were linear and the structure of the spiral flow was a simple forced vortex with a vertical circulation. The spiral flow velocity was fluctuated with a long period of several tens seconds. It was shown that large liquid temperature fluctuations were initiated when the spiral flow penetrated into a thermal stratified layer in the bend. The liquid temperature fluctuations caused the wall temperature fluctuations and two types of the wall temperature fluctuations were observed.

Control of Flow Pattern and Solidification Interface Shape in an Induction Heated Czochralski Crystal Growth System

Optical crystals grown by Czochralski technique from a solute-rich melt usually suffer defects of melt inclusion or bubble core defects, which severely affect the optical, thermal and mechanical properties of the material. It is well known that the formation of melt inclusion or bubble core is highly related to species distribution in the growth system especially at the solidification interface and the shape of the growth interface. This paper has examined the flow pattern and solidification interface changes by changing the forced convection, e.g., crystal rotation and by changing the natural convection, e.g., inserting a horizontal disk plate. The relative effect of fluid-flow convection modes in the melt associated with crystal rotation rate is represented by a dimensionless parameter, Gr/Re2. Increasing the rotation rate will cause the solid-liquid interface change from the convex shape to concave. When the crystal rotation rate is relatively low and natural convection is strong, Gr/Re2 is large. In this case, the concentration of species pertinent to melt inclusion moves down along the axis of rotation. When the crystal rotation rate is increased, the value of Gr/Re2 decreases. The precipitated composition spreads over the growing interface may then be swiped away from the growth interface by increased crystal rotation. Melt inclusion-free crystals can thus be obtained. The relationship between Gr/Re2 and growth interface shape change is achieved by numerical simulations. The stagnant point location as a function of crystal rotation is also presented, which shows that the stagnant point moves outward by increasing Reynolds number and/or reducing Grashof number. From such understanding, the interface shape and melt inclusion position can then be controlled through control of Gr/Re2 in the growth system. Many times, it is, however, not practical in the experiments to use a high rotation rate for optical crystal growth since high rotation rate will introduce the striation defects. A new design to reduce natural convection is then proposed to improve the effect of crystal rotation and to control the solidification interface shape. Numerical simulations have been performed to demonstrate the possibility of the new design. Results show that such design is very effective and practical to control the melt inclusion and the solidification interface shape.

Experiments on the Growth of Spongy Ice Near a Stagnant Point

The paper presents experimental observations on the growth of spongy ice in the vicinity of the forward stagnation point of a disc situated in a cross flow containing supercooled water droplets. Following some preliminary observations, the discussion focuses on two quantities: the ice fraction and the rate of growth of the accretion. The data presented reveal the effects of air speed, air temperature, liquid-water content, and salinity. They also suggest two morphological regimes: at higher air temperatures, the growth appeared to be crystalline columnar; at lower temperatures, smaller crystals appeared to be randomly distributed, producing a mushy accretion.

Experiments on the Growth of Spongy Ice Near a Stagnant Point

The paper presents experimental observations on the growth of spongy ice in the vicinity of the forward stagnation point of a disc situated in a cross flow containing supercooled water droplets. Following some preliminary observations, the discussion focuses on two quantities: the ice fraction and the rate of growth of the accretion. The data presented reveal the effects of air speed, air temperature, liquid-water content, and salinity. They also suggest two morphological regimes: at higher air temperatures, the growth appeared to be crystalline columnar; at lower temperatures, smaller crystals appeared to be randomly distributed, producing a mushy accretion.