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Swirling flow at recirculation zone of backward-facing step (BFS) geometry undoubtly affected by Reynolds number since it is involving rotational vortices. This flow behavior can be represented by flow intensity and reattachment length inside the geometry. BFS geometry is chosen for it is well-known characteristics visualizing swiriling flow that o...
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... BFS model is three dimensional with Step height (h) = 41mm, upstream height (H) = 81mm, expansion ratio = 1.5, total length (L) = 4050 mm and width = 20h, similar to the previous study [2], [15]. The mesh is triangular with 90.293 nodes as showed by Figure 3. Reynolds numbers varied to Re = 4290.39; ...
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... Echo characteristics in turbulence have an academic significance and a wide application value in fields of LiDAR detection, guidance and countermeasures in addition. Generally, turbulence is more difficult to study due to (a) randomness of movement; (b) obedience to the laws of viscous fluid motion; and (c) properties of high Reynolds number [16] and viscous dissipation. Experts have studied the long-range LiDAR detection of airspace targets. ...
This paper utilizes the idea of theoretical analysis to introduce a method for echo characteristics in remote detection with the pulse LiDAR of aerial targets under atmospheric conditions. A Missiles and an aircraft are selected as simulation targets. The relation among mutual mapping of target surface elements can be directly gained by setting light source and target parameters. We discuss influences on atmospheric transport conditions, target shapes and detection conditions on echo characteristics. Atmospheric transport model is introduced as weather conditions, including sunny and cloudy days, with or without turbulence. Simulation results conclude that the outline of scanned waveform can invert the target shape. These provide a theoretical basis for improving the target detection and tracking performance.
... Geometry model of the L 609 provided by Autodesk Fusion 360 and numerical method using CFD conducted with Fluent on Ansys Fluent 2021 Academic Version as shown in Figure 1. In carrying out the analysis to incompressible and inviscid fluid flow, Bernoulli equation based on the Law of Conservation of Mechanical Energy and Pressure is used as well as Reynolds number as reference for fluid velocity [4], [5]. ...
In today's era, more and more people spend most of their time indoors, with artificial climatic conditions, where thermal comfort is a basic factor such as a glazing system (ventilation), both for dimensions and material characteristics, this basic factor is very important because it affects the parameters involved in thermal comfort. One of the requirements for thermal comfort is good air circulation, good air circulation can also prevent the spread of the COVID-19 virus that is currently engulfing the world.Therefore, research is needed to analyze the air flow engineering in the room, especially the classroom to get results that will later be seen whether it has met the demands of room comfort, especially thermal comfort. The purpose of this study is to provide recommendations for the configuration of air circulation in the L609 classroom and perform a CFD analysis on air circulation in the classroom which can create thermal comfort. Based on all the simulation results carried out with 2 outlet configurations and 5 different speed fan configurations, the obtained results are in accordance with the ASHRAE 55 standard in 2020 only in the first configuration with a speed of 0.79 m/s. in the second configuration all the simulation results obtained are not in accordance with the thermal comfort limit according to ASHRAE 55 in 2020 because the speed obtained is more than 0.8 m/s and the temperature obtained is more than 297 K. Considering the COVID-19 pandemic, there must be circulation air in order to break down the aerosol concentration of the COVID-19 virus itself. Therefore, the author recommends using a classroom configuration with an open door so that air circulation can flow properly.
... Sci. 2021, 11, 11579 3 of 15 flow profile inside the bypass pathway revealed a significant circulating flow at the end of the pathway, near the sensing element's mounting location; furthermore, the sudden expansion at the inlet of the employed bypass design can lead to boundary layer separation with a reattachment point that can be situated near the sensing element area as the flow rate increases [17]. As mentioned by the authors, both of these geometry-induced effects restricted the device's measuring range. ...
... However, we should note that for flow rate values approximately above 260 kg/h (3723 SLPM), saturation in the sensor's signal was still present. A series of appropriate CFD simulations concerning the developed flow profile inside the bypass pathway revealed a significant circulating flow at the end of the pathway, near the sensing element's mounting location; furthermore, the sudden expansion at the inlet of the employed bypass design can lead to boundary layer separation with a reattachment point that can be situated near the sensing element area as the flow rate increases [17]. As mentioned by the authors, both of these geometry-induced effects restricted the device's measuring range. ...
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... The circulating flow is present also at low engine air intakes, well below 3723 SLPM (260 kg/h), while it increases considerably as the flow rate increases. Apart from the noticed circulating flow, we should also take into consideration that the sudden expansion at the inlet of the employed bypass design (i.e. after the orifice) can lead to boundary layer separation with a reattachment point that can be situated in close proximity to the sensing element area as the flow rate increases [10]. Both of the above geometry induced effects can contribute to the saturation observed at the sensor's signal. ...
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Indonesia has lots of natural resources especially in marine sector such as yellowstripe scad and long-jawed mackerel. Those fish are usually dried by fisherman for longer storage using conventional drying by heat from the sun. This conventional drying method takes hours, about two or three days depends on sun heat intensity. Based on that problem, mechanical drying system may overcome the problem. Automatic fish dryer is designed to dry the fish effectively with even heat distribution with palette rotation system which is hoped to increase productivity and economic potential for coastal communities. The prototype is designed theoretically with mechanical design to generate part specification including heater, shaft, electric motor, bearing, pulley and transmission. CFD method to discover the heat distribution inside with 5,239 nodes and STD k-ε turbulence model. A 400 mm × 500 mm × 420 mm prototype is generated to dry 2 kg of long-jawed mackerels in 5.3 h with 0.00419 g/s for drying mass flow rate from 70 to 30% water content. CFD simulation shows the exhaust fan need to be installed at outlet for better water-vapor flow distribution. This research indicates that automatic fish dryer can dry 4 times faster than conventional drying system.
