2. The Fluid Body

2020 ◽  
pp. 61-95
Keyword(s):  
Fluid Body

scholarly journals Numerical Analysis of the Dynamic Interaction between Two Closely Spaced Vertical-Axis Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2286
Author(s):  
Yutaka Hara ◽  
Yoshifumi Jodai ◽  
Tomoyuki Okinaga ◽  
Masaru Furukawa
Keyword(s):  
Wind Turbines ◽  
Power Distribution ◽  
Phase Synchronization ◽  
Average Power ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Mean Power ◽  
Vertical Axis Wind Turbines ◽  
Fluid Body ◽  
First Time

To investigate the optimum layouts of small vertical-axis wind turbines, a two-dimensional analysis of dynamic fluid body interaction is performed via computational fluid dynamics for a rotor pair in various configurations. The rotational speed of each turbine rotor (diameter: D = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (gap) between two rotors is investigated. For parallel layouts, counter-down (CD) layouts with blades moving downwind in the gap region yield a higher mean power than counter-up (CU) layouts with blades moving upwind in the gap region. CD layouts with gap/D = 0.5–1.0 yield a maximum average power that is 23% higher than that of an isolated single rotor. Assuming isotropic bidirectional wind speed, co-rotating (CO) layouts with the same rotational direction are superior to the combination of CD and CU layouts regardless of the gap distance. For tandem layouts, the inverse-rotation (IR) configuration shows an earlier wake recovery than the CO configuration. For 16-wind-direction layouts, both the IR and CO configurations indicate similar power distribution at gap/D = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulation.

scholarly journals HUBUNGAN TINGKAT PENGETAHUAN TENTANG KEBUTUHAN CAIRAN TUBUH DENGAN POLA KONSUMSI AIR MINUM PADA MAHASISWA TINGKAT I AKPER PANTI KOSALA SURAKARTA

2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Budi Herminto ◽  
Risa Setia Ismandani
Keyword(s):  
Drinking Water ◽  
Design Research ◽  
P Value ◽  
First Year ◽  
Knowledge Level ◽  
First Year Students ◽  
Fluid Body ◽  
Level Of Knowledge ◽  
High Level ◽  
The Relationship

AbstractWater represent compound which is the necessary for all living. Consumption behaviorirrigate society not yet altogether goodness, society consume water when feel thirsty anddo not so pay attention drinking water and amount matching with requirement. Purpose ofthe study to determine the relationship between the knowledge level about fluid bodyrequirement with pattern consume drinking water at student in Academy of Nursing PantiKosala Surakarta.The subject was used as population in the study was all the first year students. The totalpopulation were 139 students, and the sample were 103 students. The samplingtechnique was simple random sampling.This research method represent analytic research with design research of corelasional toknow relationship between knowledge level about fluid body requirement with patternconsume drinking water of student.The results was the high level of knowledge about the fluid body requirment were 74(72%), moderate level of knowledge about the fluid body requirment were 29 (28%), whilethe behavior of consuming appropiate water were 69 (67%), and the behavior ofconsuming inappropiate water were 34 (33%) with a p-value 0.003 <0.05 significant 95%.There was a significant relationship between the knowledge level about fluid bodyrequirement with pattern consume drinking water at student in Academy of Nursing PantiKosala Surakarta.Keywords: knowlegde level, fluid body requirement, pattern consume drinking water.

scholarly journals Flow around an inclined circular disk

2018 ◽  
Vol 851 ◽  
pp. 687-714 ◽  
Author(s):  
Song Gao ◽  
Longbin Tao ◽  
Xinliang Tian ◽  
Jianmin Yang
Keyword(s):  
Low Frequency ◽  
Circular Disk ◽  
Streamwise Direction ◽  
Chaotic State ◽  
Dominant Position ◽  
Periodic State ◽  
Flow Features ◽  
Fluid Body ◽  
Planar Symmetry ◽  
Fully Coupled

Direct numerical simulations are performed for the uniform flow around an inclined circular disk. The diameter–thickness aspect ratio ($\unicode[STIX]{x1D712}=D/t_{d}$) of the disk is 50 and the inclination angle ($\unicode[STIX]{x1D6FC}$) is considered over the range of $0^{\circ }\leqslant \unicode[STIX]{x1D6FC}\leqslant 80^{\circ }$, where $\unicode[STIX]{x1D6FC}=0^{\circ }$ refers to the condition where the flow is normal to the disk. The Reynolds number ($\mathit{Re}$), based on the short axis of projection in the streamwise direction, is defined as $\mathit{Re}=U_{\infty }D\cos \unicode[STIX]{x1D6FC}/\unicode[STIX]{x1D708}$, where $U_{\infty }$ is the velocity of the flow and $\unicode[STIX]{x1D708}$ is the kinematic viscosity. $\mathit{Re}$ is investigated over the range of 50 ${\leqslant}\mathit{Re}\leqslant$ 300. In the considered $\mathit{Re}$–$\unicode[STIX]{x1D6FC}$ parametric space, five states are observed and denoted as: (I) steady state (SS); (II) periodic state (PS); (III) periodic state with a low frequency modulation (PSL); (IV) quasi-periodic state (QP) and (V) chaotic state (CS). Both $\mathit{Re}$ and $\unicode[STIX]{x1D6FC}$ affect the bifurcation mechanism. The bifurcating sequence occurring at $\unicode[STIX]{x1D6FC}=0^{\circ }$ is generally observed over the whole $\mathit{Re}$–$\unicode[STIX]{x1D6FC}$ space, although it is advanced at small $\unicode[STIX]{x1D6FC}$ and delayed at large $\unicode[STIX]{x1D6FC}$. The advancement of thresholds for different states is due to the effects introduced by inclination, which tend to select the plane of symmetry for the wake in order to regulate the wake and intensify some flow features. Nevertheless, the bifurcations are still in the dominant position when leading a state without stable symmetry, i.e. the planar symmetry could not be recovered by small $\unicode[STIX]{x1D6FC}$. These phenomena are further discussed with respect to the vortex shedding patterns behind the disk. Furthermore, for any fixed disk, the wake behaviour is only associated with that found in the steady vertical state of a freely falling disk. The fully coupled fluid–body system is fundamentally different from the fixed cases.

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

2022 ◽  
pp. 147509022110707
Author(s):  
Ugur Can ◽  
Sakir Bal
Keyword(s):  
High Speed ◽  
Full Scale ◽  
Navier Stokes ◽  
Drag Forces ◽  
Fluid Body ◽  
Unsteady Rans ◽  
Lift Forces ◽  
Drag And Lift ◽  
Lift And Drag ◽  
Model Family

In this study, it was aimed to obtain an accurate extrapolation method to compute lift and drag forces of high-speed vessels at full-scale by using CFD (Computational Fluid Dynamics) based GEOSIM (GEOmetrically SIMilar) method which is valid for both fully planing and semi-planing regimes. Athena R/V 5365 bare hull form with a skeg which is a semi-displacement type of high-speed vessel was selected with a model family for hydrodynamic analyses under captive and free to sinkage/trim conditions. Total drag and lift forces have been computed for a generated GEOSIM family of this form at three different model scales and full-scale for Fr = 0.8 by an unsteady RANS (Reynolds Averaged Navier–Stokes) solver. k–ε turbulence model was used to simulate the turbulent flow around the hulls, and both DFBI (Dynamic Fluid Body Interaction) and overset mesh technique were carried out to model the heave and pitch motions under free to sinkage/trim condition. The computational results of the model family were used to get “drag-lift ratio curve” for Athena hull at a fixed Fr number and so the corresponding results at full scale were predicted by extrapolating those of model scales in the form of a non-dimensional ratios of drag-lift forces. Then the extrapolated full-scale results calculated by modified GEOSIM method were compared with those of full-scale CFD and obtained by Froude extrapolation technique. The modified GEOSIM method has been found to be successful to compute the main forces (lift and drag) acting on high-speed vessels as a single coefficient at full scale. The method also works accurately both under fully and semi-planing conditions.

The initial development of a jet caused by fluid, body and free-surface interaction. Part 1. A uniformly accelerating plate

1994 ◽  
Vol 268 ◽  
pp. 89-101 ◽  
Author(s):  
A. C. King ◽  
D. J. Needham
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Finite Depth ◽  
Small Time ◽  
Restoring Force ◽  
Initial Development ◽  
Thin Region ◽  
Fluid Body ◽  
Horizontal Momentum ◽  
Important Design

The flow field induced by a vertical plate accelerating into a stationary fluid of finite depth with a free surface and a gravitational restoring force is investigated. This is a model problem for some technologically important design issues such as the bow splash of a ship moving at forward speed. Experimentally it is found that a thin jet forms on the plate and rises rapidly upwards. We investigate this jet in the small-time approximation and find an analytical solution for the flow field in which the jet emerges out of a thin region where the horizontal momentum of the main flow is converted by inertial effects into a rising jet.

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