Finite element simulations of hybrid nano-Carreau Yasuda fluid with hall and ion slip forces over rotating heated porous cone

Involvement of hybrid nanoparticles a vital role to improve the efficiency of thermal systems. This report covers the utilization of different nanoparticles mixed in Carreau Yasuda material for the improvement of thermal performance. The configuration of flow situation is considered over a rotating porous cone by considering the Hall and Ion slip forces. Transport of momentum is considered to be in a rotating cone under generalized ohm’s law and heat transfer is presented by considering viscous dissipation, Joule heating and heat generation. Rheology of considered model is derived by engaging the theory proposed by Prandtl. Modeled complex PDEs are reduced into ODEs under similarity transformation. To study the physics behind this phenomenon, solution is essential. Here, FEM (Finite Element Method) is adopted to compute the solution. Furthermore, the grid independent study is reported with several graphs and tables which are prepared to note the influence of involved parameters on thermal and velocity fields. It is worth mentioning that heat transport is controlled via higher radiation parameter and it upsurges for Eckert number. Moreover, Hall and ion slip parameters are considered significant parameters to produce the enhancement in motion of fluid particles but speed of nano and hybrid nanoparticles becomes slow down versus large values of Forchheimer and Weissenberg numbers. Additionally, an enhancement in production of heat energy is addressed via large values of heat generation number and Eckert number while reduction in heat energy is occurred due to positive values of thermal radiation and Hall and ion slip parameters.

A Numerical and Experimental Study of the Time Averaged and Transient Flow Downstream of a Butterfly Valve

This research took the DN50 butterfly valve as the research object and studied the flow situation of butterfly valves with different shafts. The resistance characteristics, flow state, characteristics, and flow instability of butterfly valves with different structures were studied by experiments and numerical simulations. Research shows that the edge of the valve disc occurs flow separation, and the drag of the valve disc fluctuates non-periodically with time. Under different opening degrees, the velocity distribution downstream of the valve varies, and the effect of the shaft on the velocity fluctuation is different. Finally, the unstable region of flow downstream of the valve is determined. This study provides a reference for the use and optimization of butterfly valves.

Printing of Zirconia Parts via Fused Filament Fabrication

In this work, a process chain for the fabrication of dense zirconia parts will be presented covering the individual steps feedstock compounding, 3D printing via Fused Filament Fabrication (FFF) and thermal postprocessing including debinding and sintering. A special focus was set on the comprehensive rheological characterization of the feedstock systems applying high-pressure capillary and oscillation rheometry. The latter allowed the representation of the flow situation especially in the nozzle of the print head with the occurring low-shear stress. Oscillation rheometry enabled the clarification of the surfactant’s concentration, here stearic acid, or more general, the feedstocks composition influence on the resulting feedstock flow behavior. Finally, dense ceramic parts (best values around 99 % of theory) were realized with structural details smaller than 100 µm.

The Discrete Green's Function for Convective Heat Transfer—Part 1: Definition and Physical Understanding

The discrete Green's function (DGF) is a superposition-based descriptor of the relationship between the surface temperature and the convective heat transfer from a surface. The surface is discretized into a finite number of elements and the DGF matrix elements relate the heat transfer out of any element i to the temperature rise on every element j of the surface. For a given flow situation, the DGF is insensitive to the thermal boundary condition so it allows direct calculation of the heat transfer for any temperature distribution and noniterative solution of conjugate heat transfer problems. The diagonal elements of the matrix are determined solely by the local velocity field while the off-diagonals are determined by the spread of the thermal wake downstream of a heated element. An analytical DGF for the laminar flat-plate boundary layers is included as an example.

Highway Development and Capacity Utilisation in Ogun State, Nigeria

Highway development in Nigeria pioneered other modes of transport including rail, air, water and pipeline. It serves as the most efficient means of distributing agricultural products, locally-made products and natural resources. As a result of this, highways requires adequate planning and periodic maintenance for effective and efficient performance. This study examined traffic situation and capacity utilisation of highways in Ogun State, Nigeria with particular reference to Lagos-Ibadan, Lagos-Abeokuta and Sagamu-Benin Highways. Manual traffic count method was employed for the estimation of traffic volume and flow pattern. The count took 12 hours a day for three consecutive days (Tuesday, Thursday and Saturday) of a week. The traffic data gathered were analyzed and interpreted using descriptive and inferential techniques to determine Average Daily Traffic Volume (ADTV), flow situation and capacity utilization rate of each highway through thorough observation of inbound and outbound traffic. Findings revealed significant variation in traffic flow situation observed on Tuesday, Thursday and Saturday of selected highways. Findings also revealed that Lagos-Ibadan Highway (2,085 vehicles/hour/lane) is well utilized while Abeokuta-Lagos and Sagamu-Benin Highways are underutilized with 820 and 1,184 vehicles/hour/lane respectively. Improvement measures and strategies to address traffic flow situation including route development and utilisation issues on the highways were proposed.

Experimental investigation on heat transfer augmentation of transverse twisted tapes in a confined rectangular channel

This study investigates the influence of twisted tape inserts on a flow pathway in transverse direction of a flow situation. An array of twisted tapes was mounted on the confined channel to disturb the flow to enhance the heat transfer. The test section had 20 twisted tapes of 35-mm height, 10-mm width and a twist angle of 180° mounted on a silica gel–coated plate. Experiments were conducted on the fabricated experimental setup for different discharge conditions. The Reynolds number considered for the study ranged from 2300 to 3500, and the heat inputs varied from 50 to 250 W, with an interval of 50 W. To visualize the presence of twisted tapes on the flow path, the rectangular channel was visualized by laser flow visualization method, which reported the impact of the twisted tapes on the flow. The existence of twisted tape affects the flow, and it forms a swirl that provides a proper mixing of fluid to enhance heat transfer. The outcome of the present investigation provides a solution to enhance heat transfer and proposes the use of twisted tapes instead of using segmented fins in design of fins.

Numerical Simulations of Flow in Electrostatic Precipitators

Electrostatic precipitators are widely used in power generation and industry to separate solid particles from flue gases. They need relatively homogeneous distribution of the flue gas inside otherwise the required efficiency cannot be ensured. The paper shows how to approach some of possible troubles with distribution of the stream inside of the filters caused by unsuitable design of ducts in front of the device or by inlet parts of filters. Three filters in operation are presented as examples which seem to be similar, but their behaviour is different. CFD simulations partialy validated by measurement were used to evaluate the existing flow situation. Design changes were proposed and further investigated to improve the flows in the precipitator.

Activation Energy and Second Order Slip in Bioconvection of Oldroyd-B Nanofluid over a Stretching Cylinder: A Proposed Mathematical Model

The thermal performances based on the interaction of nanoparticles are the topic of great interest in recent years. In the current continuation, we have utilized the activation energy and thermal radiation consequences in the bioconvection flow of magnetized Oldroyd-B nanoparticles over a stretching cylinder. As a novelty, the second order slip features (Wu’s slip) and convective Nield boundary assumptions are also introduced for the flow situation. The heat performances of nanofluids are captured with an evaluation of the famous Buongiorno’s model which enables us to determine the attractive features of Brownian motion and thermophoretic diffusion. The suggested thermal system is based on the flow velocity, nanoparticles temperature, nanoparticles volume fraction and motile microorganisms. The governing flow equations for the flow problem are constituted with relevant references for which numerically solution is developed via shooting algorithm. A detailed graphically analysis for the assisted flow problem is performed in view of the involved parameters. Although some studies are available in the literature which deals with the flow of various fluids over-stretching cylinder, the phenomenon of bioconvection and other interesting features are not reported yet. Therefore, present scientific computations are performed to fill this gap and the reported results can be more useful for the enhancement of thermal extrusion processes, solar energy systems, and biofuels.

Effects of Climate Change and Flow Regulation on the Flow Characteristics of a Low-Relief River within Southern Boreal Climate Area

We investigated how hydro-climatological changes would affect fluvial forces and inundated area during a typical high-flow situation (MHQ, mean high discharge), and how adaptive regulation could attenuate the climate change impacts in a low-relief river of the Southern Boreal climate area. We used hydrologically modeled data as input for 2D hydraulic modeling. Our results show that, even though the MHQ will increase in the future (2050–2079), the erosional power of the flow will decrease on the study area. This can be attributed to the change of timing in floods from spring to autumn and winter, when the sea levels during flood peaks is higher, causing backwater effect. Even though the mean depth will not increase notably (from 1.14 m to 1.25 m) during MHQ, compared to the control period (1985–2014), the inundated area will expand by 15% due to the flat terrain. The increase in flooding may be restrained by adaptive regulations: strategies favoring ecologically sustainable and recreationally desirable lake water levels were modeled. The demands of environment, society, and hydropower are not necessarily contradictory in terms of climate change adaptation, and regulation could provide an adaptive practice in the areas of increased flooding.