How the circulation and axial velocity deficit in Batchelor vortices affect their disturbance growth?

2020 ◽  
Vol 32 (7) ◽  
pp. 076107
Author(s):  
Toshihiko Hiejima
Keyword(s):  
Axial Velocity ◽  
Velocity Deficit ◽  
Disturbance Growth

Onset of orbital motion in a trailing vortex from an oscillating wing

2018 ◽  
Vol 856 ◽  
pp. 257-287 ◽  
Author(s):  
G. Fishman ◽  
D. Rockwell
Keyword(s):  
Strouhal Number ◽  
Axial Velocity ◽  
Orbital Motion ◽  
Extreme Values ◽  
Three Dimensional ◽  
Swirl Ratio ◽  
Streamwise Direction ◽  
Velocity Deficit ◽  
Streamwise Location ◽  
Dimensional Reconstruction

The onset and development of orbital motion of a trailing vortex from a wing undergoing small amplitude heaving motion is investigated using stereo particle image velocimetry in conjunction with three-dimensional reconstruction techniques. The effect of Strouhal number is examined via space–time representations of axial and azimuthal vorticity, axial velocity deficit and swirl ratio. At low Strouhal number, the undulation of the vortex remains unidirectional with no amplification in the streamwise direction. In contrast, at high Strouhal number, the amplitude of vortex undulation can increase by up to a factor of ten in the streamwise direction. These large amplitudes occur during orbital motion of the vortex. Irrespective of the value of either the Strouhal number of excitation or the streamwise location along the undulating vortex, generic physical mechanisms occur. Changes in curvature along the vortex are closely related to changes in the axial velocity deficit, extreme values of axial vorticity and swirl ratio and the onset and attenuation of pronounced azimuthal vorticity.

Axisymmetric flow near the critical point on the moving boundary

2010 ◽  
Vol 7 ◽  
pp. 182-190
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh. Nasibullaeva
Keyword(s):  
Fluid Flow ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Axial Velocity ◽  
Moving Boundary ◽  
Axisymmetric Flow ◽  
Boundary Motion ◽  
Newton Raphson ◽  
Raphson Method

In this paper the investigation of the axisymmetric flow of a liquid with a boundary perpendicular to the flow is considered. Analytical equations are derived for the radial and axial velocity and pressure components of fluid flow in a pipe of finite length with a movable right boundary, and boundary conditions on the moving boundary are also defined. A numerical solution of the problem on a finite-difference grid by the iterative Newton-Raphson method for various velocities of the boundary motion is obtained.

scholarly journals Stability of a Viscous Liquid Jet in a Coaxial Twisting Compressible Airflow

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 918
Author(s):  
Li-Mei Guo ◽  
Ming Lü ◽  
Zhi Ning
Keyword(s):  
Viscous Liquid ◽  
Axial Velocity ◽  
Liquid Velocity ◽  
Velocity Ratio ◽  
Dominant Mode ◽  
Liquid Jet ◽  
Axisymmetric Mode ◽  
Jet Instability ◽  
Jet Stability ◽  
Jet Breakup

Based on the linear stability analysis, a mathematical model for the stability of a viscous liquid jet in a coaxial twisting compressible airflow has been developed. It takes into account the twist and compressibility of the surrounding airflow, the viscosity of the liquid jet, and the cavitation bubbles within the liquid jet. Then, the effects of aerodynamics caused by the gas–liquid velocity difference on the jet stability are analyzed. The results show that under the airflow ejecting effect, the jet instability decreases first and then increases with the increase of the airflow axial velocity. When the gas–liquid velocity ratio A = 1, the jet is the most stable. When the gas–liquid velocity ratio A > 2, this is meaningful for the jet breakup compared with A = 0 (no air axial velocity). When the surrounding airflow swirls, the airflow rotation strength E will change the jet dominant mode. E has a stabilizing effect on the liquid jet under the axisymmetric mode, while E is conducive to jet instability under the asymmetry mode. The maximum disturbance growth rate of the liquid jet also decreases first and then increases with the increase of E. The liquid jet is the most stable when E = 0.65, and the jet starts to become more easier to breakup when E = 0.8425 compared with E = 0 (no swirling air). When the surrounding airflow twists (air moves in both axial and circumferential directions), given the axial velocity to change the circumferential velocity of the surrounding airflow, it is not conducive to the jet breakup, regardless of the axisymmetric disturbance or asymmetry disturbance.

scholarly journals Improved color Doppler for cerebral blood flow axial velocity imaging

2020 ◽  
pp. 1-1
Author(s):  
Jianbo Tang ◽  
Kivilcim Kilic ◽  
Thomas L. Szabo ◽  
David A. Boas
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Axial Velocity ◽  
Color Doppler ◽  
Velocity Imaging

The Flow of an Incompressible Fluid through an Axial Turbo-Machine with any Number of Rows

1951 ◽  
Vol 3 (2) ◽  
pp. 133-144 ◽  
Author(s):  
J. W. Railly
Keyword(s):  
Aspect Ratio ◽  
Incompressible Fluid ◽  
Radial Velocity ◽  
Simple Form ◽  
High Aspect Ratio ◽  
Unknown Function ◽  
Axial Velocity ◽  
Velocity Fields ◽  
Single Row ◽  
Undetermined Constant

SummaryA method is described whereby, at any point in an infinite parallel annulus, the approximate axial velocity due to a single row of high aspect ratio blades may be calculated from a knowledge of the conditions of flow adjacent to the blades. The method is based on the assumption of a simplified expression for the radial velocity, being the product of an unknown function of the radius and an exponential term independent of the radius containing an undetermined constant; the function and the undetermined constant are calculated by reference to the conditions of flow in the plane of the row considered. The flow due to any number of rows is then obtained by summing the radial velocity fields due to each row and obtaining the axial velocities by integration of the equation of continuity.The solution of the problem with infinitely many rows is shown to have a simple form by virtue of the fact that the flow (provided that the velocities remain finite) settles down to a pattern which is periodic by one stage pitch.

On the disturbance growth in an asymptotic suction boundary layer

2003 ◽  
Vol 482 ◽  
pp. 51-90 ◽  
Author(s):  
J. H. M. FRANSSON ◽  
P. H. ALFREDSSON
Keyword(s):  
Boundary Layer ◽  
Asymptotic Suction ◽  
Disturbance Growth

Management of regional enteritis

1966 ◽  
Vol 4 (23) ◽  
pp. 90-91
Keyword(s):  
Weight Loss ◽  
Small Bowel ◽  
Chronic Inflammation ◽  
Regional Enteritis ◽  
Skin Lesions ◽  
Blind Loop Syndrome ◽  
Electrolyte Disturbance ◽  
Extensive Involvement ◽  
Acute Ileitis ◽  
Disturbance Growth

Regional enteritis (Crohn’s disease) is an uncommon chronic inflammation of unknown cause involving one or more parts of the gut.1–3 The affected parts are often thickened: the mucosa is usually ulcerated and there may be adhesions and fistulae. This can cause diarrhoea, steatorrhoea, pain, and acute and chronic obstruction. Malabsorption occurs in extensive involvement of the small bowel or in the ‘blind loop’ syndrome due to strictures, fistulae or by-pass operations, and in addition protein may be lost in the bowel. The fistulae may occur between loops of bowel, and anal fistulae are common. These disorders can cause malaise, fever, anaemia, weight loss, hypoproteinaemia and electrolyte disturbance. Growth may be arrested. Skin lesions, arthropathy and iritis may develop. The first attack may occur at any age, and the disease usually runs a chronic and unpredictable course. However, acute ileitis, diagnosed surgically, does not usually recur,4–6 and it may be a different condition.6

Sign in / Sign up

Export Citation Format

Share Document