Flow measurements in the near wake of a smooth sphere and one mimicking a pine cone

2020 ◽  
Vol 5 (7) ◽  
Author(s):  
Tom David ◽  
Lior Eshbal ◽  
Vladislav Rinsky ◽  
René van Hout
Keyword(s):  
Near Wake ◽  
Flow Measurements ◽  
Pine Cone ◽  
Smooth Sphere

Wake Flow Measurements Behind Rotating Smooth Spheres and Baseballs Near Critical Reynolds Numbers

2021 ◽  
Author(s):  
David Rooney ◽  
Patrick Mortimer ◽  
Frank Tricouros ◽  
John Vaccaro
Keyword(s):  
Tangential Velocity ◽  
Reynolds Numbers ◽  
Stereoscopic Particle Image Velocimetry ◽  
Wake Flow ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Freestream Velocity ◽  
Magnus Effect ◽  
Critical Reynolds Numbers ◽  
Smooth Sphere

Abstract The flow field behind spinning baseballs at two different seam orientations was investigated, and compared with a smooth sphere, to isolate effects of seams on the Magnus effect at Reynolds numbers of 5×104 and 1×105. The rotational speed of the three spheres varied from 0-2400 rpm, which are typical of spin rates imparted to a thrown baseball. These spin rates are represented non-dimensionally as a relative spin rate relating the surface tangential velocity to the freestream velocity, and varied between 0-0.94. Mean velocity profiles, streamline patterns, and power spectral density of the velocity signals were taken using hot-wire anemometry and/or stereoscopic particle image velocimetry in the wake region. The sphere wake orientation changed over a range of relative spin rates, indicating an inverse Magnus effect. Vortex shedding at a Strouhal number of 0.25 was present on the sphere at low relative spin rates. However, the seams on the baseball prevented any consequential change in wake orientation and, at most spin rates, suppressed the shedding frequency exhibited by the sphere. Instead, frequencies corresponding to the seam rotation rates were observed in the wake flow. It was concluded that the so-called inverse Magnus effect recorded by previous investigators at specific combinations of Reynolds number and relative spin rate on a sphere exists for a smooth sphere or an axisymmetrically dimpled sphere but not for a baseball near critical Reynolds numbers, where the wake flow pattern is strongly influenced by the raised seams.

Mean-Flow Measurements in the Boundary Layer and Wake and Wave Field of a Series 60 CB = 0.6 Ship Model—Part 1: Froude Numbers 0.16 and 0.316

1992 ◽  
Vol 36 (04) ◽  
pp. 360-377
Author(s):  
Y. Toda ◽  
F. Stern ◽  
J. Longo
Keyword(s):  
Boundary Layer ◽  
Froude Number ◽  
Scale Effects ◽  
Near Field ◽  
Field Measurements ◽  
Mean Flow ◽  
Near Wake ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Wave Induced

Part 1 of this two-part paper presents results from a towing-tank experiment conducted in order to explicate the influence of wavemaking by a surface-piercing body on its boundary layer and wake and provide detailed documentation of the complete flow field appropriate for validating computational methods. Mean-velocity and pressure field measurements were performed for Froude numbers 0.16 and 0.316 for a 3.048 m Series 60 CB = 0.6 hull form at numerous stations from the bow to the stern and into the near wake. For Froude number = 0.316, free-surface effects are very significant, whereas for Froude number = 0.16, they are negligible, except near the bow, such that comparison of the results enables the identification of the salient features of the wave-induced effects. Wave profiles and local and global elevations were also measured. In addition, resistance tests were conducted. The experimental equipment and procedures are described and the results are discussed to point out the essential differences between the flows at low and high Froude number. On the forebody, the differences are primarily in the outer (inviscid) flow, except at the bow, whereas on the afterbody and in the near wake, both the inner (viscous) and outer flows are altered. The results are discussed to assess the nature of the interaction between wavemaking and the boundary layer and wake. Most of the interaction can be explicated as a result of the wave elevations, wave-induced pressure gradients, and the displacement effects of the boundary layer. Part 2 concerns scale effects on near-field wave patterns and comparisons between the experimental results and inviscid theory.

Measurements in the Near-Wake Region of a Slender, Self-Propelled Model at Pitch or Yaw

1983 ◽  
Vol 27 (04) ◽  
pp. 227-235 ◽  
Author(s):  
J. Schetz ◽  
H. Lee ◽  
F. Kong
Keyword(s):  
Turbulent Flow ◽  
Flow Characteristics ◽  
Wake Region ◽  
Mean Flow ◽  
Near Wake ◽  
Flow Measurements ◽  
Vertical Control ◽  
Straight Line ◽  
Head Probe ◽  
Control Surfaces

An experimental investigation of the near-wake region of a slender, propeller-driven model at pitch or yaw was undertaken in the Virginia Tech low-turbulence wind tunnel. The control surfaces on the model were set to render the model in equilibrium for the case with model pitch. The vehicle design was such that the vertical control surfaces were insufficient to achieve an equilibrium condition with the model at yaw. This is neither unusual nor undesirable, since such a vehicle can turn freely and there is little desire to operate in a straight line at yaw. A yaw-head probe was used for mean flow measurements, and a hot-wire anemometer with a normal, single wire or an X-wire served to obtain turbulent flow characteristics. The control surfaces were found to have mainly local influences on the flow field. In the pitch case, good symmetry was exhibited on both mean and turbulent flow quantities, but the lack of complete, all-directional equilibrium in the yaw case prevented the achievement of symmetry.

Clinical and Experimental Analysis of 201Thallium Uptake of the Heart

1978 ◽  
Vol 17 (04) ◽  
pp. 142-148
Author(s):  
U. Büll ◽  
S. Bürger ◽  
B. E. Strauer
Keyword(s):  
Oxygen Consumption ◽  
Left Ventricle ◽  
Muscle Mass ◽  
Myocardial Oxygen Consumption ◽  
Animal Experiments ◽  
Left Ventricular ◽  
Left Ventricular Wall ◽  
Ventricular Wall ◽  
Flow Measurements ◽  
Myocardial Flow

Studies were carried out in order to determine the factors influencing myocardial 201T1 uptake. A total of 158 patients was examined with regard to both 201T1 uptake and the assessment of left ventricular and coronary function (e. g. quantitative ventriculography, coronary arteriography, coronary blood flow measurements). Moreover, 42 animal experiments (closed chest cat) were performed. The results demonstrate that:1) 201T1 uptake in the normal and hypertrophied human heart is linearly correlated with the muscle mass of the left ventricle (LVMM);2) 201T1 uptake is enhanced in the inner (subendocardial) layer and is decreased in the outer (subepicardial) layer of the left ventricular wall. The 201T1 uptake of the right ventricle is 40% lower in comparison to the left ventricle;3) the basic correlation between 201T1 uptake and LVMM is influenced by alterations of both myocardial flow and myocardial oxygen consumption; and4) inotropic interventions (isoproterenol, calcium, norepinephrine) as well as coronary dilatation (dipyridamole) may considerably augment 201T1 uptake in accordance with changes in myocardial oxygen consumption and/or myocardial flow.It is concluded that myocardial 201T1 uptake is determined by multiple factors. The major determinants have been shown to include (i) muscle mass, (ii) myocardial flow and (iii) myocardial oxygen consumption. The clinical data obtained from patient groups with normal ventricular function, with coronary artery disease, with left ventricular wall motion abnormalities and with different degree of left ventricular hypertrophy are correlated with quantitated myocardial 201T1 uptake.

Partition Coefficient of 133Xe between Blood and Eye Tissues

1975 ◽  
Vol 14 (04) ◽  
pp. 301-309
Author(s):  
A. Marczak ◽  
A. Moszczyńska-Kowalska ◽  
H. Kowalski
Keyword(s):  
Partition Coefficient ◽  
Aqueous Humour ◽  
Vitreous Body ◽  
Flow Measurements ◽  
Solubility Coefficient ◽  
Eye Muscles ◽  
Eye Tissues ◽  
Relative Solubility ◽  
Blood Flow Measurements

SummaryThe relative solubility coefficient of 133Xe and the tissue-blood partition coefficient for the aqueous humour vitreous body, conjunctiva and external eye muscles of the rabbit were determined in vitro at 37° C and at various haematocrit values. The partition coefficient for haematocrit 40 was: for the aqueous humour 0,49 ml/ml, for the vitreous body 0,50 ml/ml, for the conjunctiva 0,81 ml/g and for the external eye muscles 0,77 ml/g. It was found that the solubility of 133Xe in rabbit erythrocytes is about 50 per cent higher than that in human red cells. The consequences of this fact for the precision of blood flow measurements by the method of tissue clearance are discussed.

Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

2020 ◽  
pp. 41-44
Author(s):  
Anatoly Kusher
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Water Flow ◽  
Flow Measurement ◽  
Water Discharge ◽  
Critical Depth ◽  
Flow Measurements ◽  
Study Results ◽  
Flow Velocity Profile ◽  
Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

Pressure-Flow Measurements for Selected Oral and Nasal Sound Segments Produced by Normal Adults

1992 ◽  
Vol 29 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Meri L. Andreassen ◽  
Bonnie E. Smith ◽  
Thomas W. Guyette
Keyword(s):  
Limited Information ◽  
Flow Data ◽  
Female Adult ◽  
Flow Measurements ◽  
Pressure Flow ◽  
Orifice Area ◽  
Normative Pressure ◽  
Categorization Scheme ◽  
Velopharyngeal Function ◽  
Normal Adults

Pressure-flow data are often used to provide information about the adequacy of velopharyngeal valving for speech. However, there is limited information available concerning simultaneous pressure-flow measurements for oral and nasal sound segments produced by normal speakers. This study provides normative pressure, flow, and velopharyngeal orifice area measurements for selected oral and nasal sound segments produced by 10 male and 10 female adult speakers. An aerodynamic categorization scheme of velopharyngeal function, including one typical category and three atypical categories (open, closed, and mixed) is proposed.

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