Incipient Separation Near Corners

2018 ◽  
Author(s):  
Anatoly I. Ruban
Keyword(s):  
Corner Point ◽  
Analytic Form ◽  
The Body ◽  
Recirculation Region ◽  
Body Contour ◽  
Concave Corner ◽  
Attached Flow ◽  
Surface Deflection ◽  
Interaction Problem ◽  
Incipient Separation

Chapter 4 analyses the transition from an attached flow to a flow with local recirculation region near a corner point of a body contour. It considers both subsonic and supersonic flow regimes, and shows that the flow near a corner can be studied in the framework of the triple-deck theory. It assumes that the body surface deflection angle is small, and formulates the linearized viscous-inviscid interaction problem. Its solution is found in an analytic form. It also presents the results of the numerical solution of the full nonlinear problem. It shows how, and when, the separation region forms in the boundary layer. In conclusion, it suggests that in the subsonic flow past a concave corner, the solution is not unique.

Preoperative and Postoperative Management of the Body Contour Patient

1996 ◽  
Vol 16 (4) ◽  
pp. 218-223
Author(s):  
R. Rohrich ◽  
P. B. Fodor ◽  
J. J. Petry ◽  
P. Vash
Keyword(s):  
Postoperative Management ◽  
The Body ◽  
Body Contour

Morphological characterization of Trichotylenchus gorganiensis n. sp. (Nematoda: Dolichodoridae) and photomicrographs of several other species of the subfamily Telotylenchinae Siddiqi, 1960

Zootaxa ◽  
2018 ◽  
Vol 4526 (4) ◽  
pp. 447
Author(s):  
REZA GHADERI ◽  
AKBAR KAREGAR ◽  
ESMAEIL MIRAEIZ
Keyword(s):  
New Species ◽  
Morphological Characterization ◽  
The Body ◽  
Morphometric Data ◽  
Tail Region ◽  
Body Contour ◽  
Closely Related Species ◽  
Pharyngeal Bulb ◽  
Anal Sac

Trichotylenchus gorganiensis n. sp. is described and illustrated based on morphological and morphometric data. The new species is characterized by its 760–1073 µm long body, conoid-rounded lip region continuous with the body contour and bearing 5–7 fine striae, 22.0–24.5 µm long stylet, basal pharyngeal bulb offset or slightly overlapping intestine, post-anal sac extending 50–73 % of the tail region, and cylindrical or subclavate tail with a striated terminus. Differences of the new species from the closely related species T. astriatus, T. astriatoides, T. changlingensis and T. papyrus are discussed. Photomicrographs and several taxonomic notes on 13 other species of Telotylenchinae, collected from Iran, are provided. 

Determining the nominal body contour image using wideband millimeter-wave radar for characterizing person-worn threats

2021 ◽  
pp. 1-7
Author(s):  
Mohammad M. Tajdini ◽  
Carey M. Rappaport
Keyword(s):  
Millimeter Wave ◽  
Cross Section ◽  
Homeland Security ◽  
Bilateral Symmetry ◽  
The Body ◽  
Airport Security ◽  
Screening Process ◽  
Body Contour ◽  
Millimeter Wave Radar ◽  
Wave Radar

Abstract Precise characterization of concealed person-worn objects will speed up the passenger screening process by reducing the rate of nuisance alarms, while also enhancing the airport security imaging systems. This paper presents an automatic, real-time method for wideband millimeter-wave radar identification of the nominal surface contours of the human body – even with affixed foreign objects or when a segment of the body cross-section is not captured by the radar – without relying on the body's bilateral symmetry. The developed method is verified experimentally when applied to the actual images generated by a laboratory airport scanning prototype developed recently by the US Department of Homeland Security (DHS). Our method uses the noisy collection of radar cross-section reflectivity data to extract the main contours and estimates the nominal body surface cross-sections through fitting a small-term Fourier series of circumferential variation. This is a necessary step for accurate characterizing of concealed terrorist threat objects affixed to the body.

Perspective: Numerical Simulations of Wakes and Blade-Vortex Interaction

1994 ◽  
Vol 116 (1) ◽  
pp. 5-21 ◽  
Author(s):  
Dean T. Mook ◽  
Bonian Dong
Keyword(s):  
Incompressible Flows ◽  
Lower Surface ◽  
The Body ◽  
Spatial Density ◽  
Inviscid Fluid ◽  
Time Step ◽  
Trailing Edge ◽  
Blade Vortex Interaction ◽  
Attached Flow ◽  
Viscous Core

A method for simulating incompressible flows past airfoils and their wakes is described. Vorticity panels are used to represent the body, and vortex blobs (vortex points with their singularities removed) are used to represent the wake. The procedure can be applied to the simulation of completely attached flow past an oscillating airfoil. The rate at which vorticity is shed from the trailing edge of the airfoil into the wake is determined by simultaneously requiring the pressure along the upper and lower surface streamlines to approach the same value at the trailing edge and the circulation around both the airfoil and its wake to remain constant. The motion of the airfoil is discretized, and a vortex is shed from the trailing edge at each time step. The vortices are convected at the local velocity of fluid particles, a procedure that renders the pressure continuous in an inviscid fluid. When the vortices in the wake begin to separate they are split into more vortices, and when they begin to collect they are combined. The numerical simulation reveals that the wake, which is originally smooth, eventually coils, or wraps, around itself, primarily under the influence of the velocity it induces on itself, and forms regions of relatively concentrated vorticity. Although discrete vortices are used to represent the wake, the spatial density of the vortices is so high that the computed velocity profiles across a typical region of concentrated vorticity are quite smooth. Although the computed wake evolves in an entirely inviscid model of the flowfield, these profiles appear to have a viscous core. The computed spacing between the regions of concentrated vorticity in the wake and the circulations around them are in good agreement with the experimental results. As an application, a simulation of the interaction between vorticity in the oncoming stream and a stationary airfoil is also discussed.

scholarly journals Molecular and morphological characterisation of Rotylenchus vitis n. sp. (Nematoda: Hoplolaimidae) infectinggrapevine in southern Spain

Nematology ◽  
2012 ◽  
Vol 14 (2) ◽  
pp. 235-247 ◽  
Author(s):  
Carolina Cantalapiedra-Navarrete ◽  
Gracia Liébanas ◽  
Antonio Archidona-Yuste ◽  
Juan E. Palomares-Rius ◽  
Pablo Castillo
Keyword(s):  
Phylogenetic Analysis ◽  
The Body ◽  
Southern Spain ◽  
Rrna Genes ◽  
Species Differentiation ◽  
Body Contour ◽  
Morphological Characterisation ◽  
Pharyngeal Region ◽  
Stylet Length

Rotylenchus vitis n. sp., a new amphimictic species infesting soil and roots of commercial vineyards in southern Spain, is described. Rotylenchus vitis n. sp. is characterised by a truncate lip region with 7-9 annuli and continuous with the body contour, lateral fields areolated at pharyngeal region only, body without longitudinal striations, stylet length of 36-48 μm, vulva position at 47-57%, tail rounded to hemispherical with 13-21 annuli. Morphologically, this species is related to R. cazorlaensis, R. capitatus, R. elegans, R. fabalus, R. iranicus, R. labiodiscus, R. montanus and R. troncapitatus. The results of the phylogenetic analysis based on the sequences of the D2-D3 expansion regions of the 28S and ITS1-rRNA genes confirmed the species differentiation and the close molecular relationship between R. eximius and R. montanus, respectively.

A Method for Inverse Aerofoil and Cascade Design by Surface Vorticity

1982 ◽  
Author(s):  
R. I. Lewis
Keyword(s):  
Velocity Distribution ◽  
Incompressible Flow ◽  
Design Tool ◽  
The Body ◽  
Surface Velocity ◽  
Classical Solutions ◽  
Analysis Tool ◽  
Attached Flow ◽  
Turbomachine Blade

Surface vorticity theory, normally considered as an analysis tool, has been modified to operate as a design tool whereby the shapes of components may be found to produce a prescribed surface velocity in incompressible flow. The basis of the method is presented and checked against classical solutions for cylindrical and diamond shaped struts with fully attached flow. A procedure for turbomachine blade or aerofoil design is outlined and illustrated with back checks via Martensen’s method. The method allows specification of velocity distribution on either or both surfaces of the body. If only one surface of an aerofoil or blade is prescribed, the user is allowed to specify profile thickness also.

Analysis of the flow field around a rudder in the wake of a simplified marine propeller

2017 ◽  
Vol 814 ◽  
pp. 547-569 ◽  
Author(s):  
Roberto Muscari ◽  
Giulio Dubbioso ◽  
Andrea Di Mascio
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
The Body ◽  
Tip Vortex ◽  
Tip Vortices ◽  
Propeller Wake ◽  
Instantaneous Flow Field ◽  
The Mean ◽  
Flow Variables ◽  
Interaction Problem

The vortex–body interaction problem, which characterizes the flow field of a rudder placed downstream of a single-blade marine rotor, is investigated by numerical simulations. The particular topology of the propeller wake, consisting of a helicoidal vortex detached from the blade tips (tip vortex) and a longitudinal, streamwise oriented vortex originating at the hub (hub vortex), embraces two representative mechanisms of vortex–body collisions: the tip vortices impact almost orthogonally to the mean plane, whereas the hub vortex travels in the mean plane of the wing (rudder), perpendicularly to its leading edge. The two vortices evolve independently only during the approaching and collision phases. The passage along the body is instead characterized by strong interaction with the boundary layer on the rudder and is followed by reconnection and merging in the middle and far wake. The features of the wake were investigated by the $\unicode[STIX]{x1D706}_{2}$-criterion (Jeong & Hussain, J. Fluid Mech., vol. 285, 1995, pp. 69–94) and typical flow variables (pressure, velocity and vorticity) of the instantaneous flow field; wall pressure spectra were analysed and related to the tip and hub vortices evolution, revealing a non-obvious behaviour of the loading on the rudder that can be related to undesired unsteady loads.

Radiation of waves by a cylinder submerged in water with ice floe or polynya

2015 ◽  
Vol 784 ◽  
pp. 373-395 ◽  
Author(s):  
Izolda V. Sturova
Keyword(s):  
Elastic Plate ◽  
Diffraction Problem ◽  
Open Water ◽  
Finite Depth ◽  
The Body ◽  
Elastic Plates ◽  
Radiation Problem ◽  
Radiation Load ◽  
Body Contour ◽  
Damping Coefficients

The problems of radiation (sway, heave and roll) of surface and flexural-gravity waves by a submerged cylinder are investigated for two configurations, concerning; (i) a freely floating finite elastic plate modelling an ice floe, and (ii) two semi-infinite elastic plates separated by a region of open water (polynya). The fluid of finite depth is assumed to be inviscid, incompressible and homogeneous. The linear two-dimensional problems are formulated within the framework of potential-flow theory. The method of mass sources distributed along the body contour is applied. The corresponding Green’s function is obtained by using matched eigenfunction expansions. The radiation load (added mass and damping coefficients) and the amplitudes of vertical displacements of the free surface and elastic plates are calculated. Reciprocity relations which demonstrate both symmetry of the radiation load coefficients and the relation of damping coefficients with the far-field form of the radiation potentials are found. It is shown that wave motion essentially depends on the position of the submerged body relative to the elastic plate edges. The results of solving the radiation problem are compared with the solution of the diffraction problem. It is noted that resonant frequencies in the radiation problem correlate with those frequencies at which the reflection coefficient in the diffraction problem has a local minimum.

scholarly journals HYDRODYNAMIC ASPECTS OF DESIGN AND ATTACHMENT OF A BACK-MOUNTED DEVICE IN PENGUINS

1994 ◽  
Vol 194 (1) ◽  
pp. 83-96 ◽  
Author(s):  
R Bannasch ◽  
RP Wilson ◽  
B Culik
Keyword(s):  
Wind Tunnel ◽  
The Body ◽  
Hydrodynamic Resistance ◽  
Water Tank ◽  
Body Contour

Wind tunnel and water tank experiments were carried out on a penguin model in order to optimise the shape and attachment of a back-mounted datalogger. Device-induced turbulence was minimised when the unit was placed in the most caudal position. Drag was further reduced by shaping the device to match the body contour. The hydrodynamic resistance of the package could be reduced by 65 % compared with an earlier unit. These results are discussed together with results from new studies on kinematics and energetics of underwater swimming of live instrumented penguins.

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