scholarly journals Numerical Study on the Effect of Free Surface and Solid Wall on the Axisymmetric Vortex Breakdown in a Cylindrical Container at Aspect Ratio of h=2.0.

2000 ◽  
Vol 66 (643) ◽  
pp. 738-746
Author(s):  
Reima IWATSU
Keyword(s):  
Free Surface ◽  
Aspect Ratio ◽  
Vortex Breakdown ◽  
Numerical Study ◽  
Solid Wall ◽  
Cylindrical Container ◽  
Axisymmetric Vortex

Topology of vortex breakdown in closed polygonal containers

2017 ◽  
Vol 820 ◽  
pp. 263-283 ◽  
Author(s):  
Igor V. Naumov ◽  
Irina Yu. Podolskaya
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Vortex Breakdown ◽  
Laser Doppler Anemometry ◽  
Reynolds Numbers ◽  
Cylindrical Container ◽  
Stagnation Points ◽  
Aspect Ratios ◽  
Particle Visualization ◽  
Cross Section Geometry

The topology of vortex breakdown in the confined flow generated by a rotating lid in a closed container with a polygonal cross-section geometry has been analysed experimentally and numerically for different height/radius aspect ratios $h$ from 0.5 to 3.0. The locations of stagnation points of the breakdown bubble emergence and corresponding Reynolds numbers were determined experimentally and numerically by STAR-CCM+ computational fluid dynamics software for square, pentagonal, hexagonal and octagonal cross-section configurations. The flow pattern and velocity were observed and measured by combining seeding particle visualization and laser Doppler anemometry. The vortex breakdown size and position on the container axis were identified for Reynolds numbers ranging from 500 to 2800 in steady flow conditions. The obtained results were compared with the flow structure in the closed cylindrical container. The results allowed revealing regularities of formation of the vortex breakdown bubble depending on $Re$ and $h$ and the cross-section geometry of the confined container. It was found in a diagram of $Re$ versus $h$ that reducing the number of cross-section angles from eight to four shifts the breakdown bubble location to higher Reynolds numbers and a smaller aspect ratio. The vortex breakdown bubble area for octagonal cross-section was detected to correspond to the one for the cylindrical container but these areas for square and cylindrical containers do not overlap in the entire range of aspect ratio.

A Study of Axisymmetric Vortex Breakdown Flows in Confined Cylindrical Container

2019 ◽  
Vol 2019.25 (0) ◽  
pp. 19H11
Author(s):  
Yuki NAKATSUKA ◽  
Koji SUZUKI ◽  
Reima IWATSU ◽  
Hide S. KOYAMA
Keyword(s):  
Vortex Breakdown ◽  
Cylindrical Container ◽  
Axisymmetric Vortex

Vortex Breakdown in an Enclosed Cylinder With a Partially Rotating Bottom-Wall

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
P. Yu ◽  
T. S. Lee ◽  
Y. Zeng ◽  
H. T. Low
Keyword(s):  
Aspect Ratio ◽  
Vortex Breakdown ◽  
Numerical Study ◽  
Axisymmetric Flow ◽  
Rotating Disk ◽  
Bottom Wall ◽  
Cylindrical Chamber ◽  
Noticeable Effect ◽  
Disk Radius ◽  
Boundary Curves

A numerical study of the axisymmetric flow in a cylindrical chamber of height H is presented, which is driven by a bottom disk rotating at angular velocity Ω. However, unlike most previous studies, the present rotating disk is of smaller radius than the bottom-wall. The boundary curves for the onset of vortex breakdown are presented using different definitions of the nondimensional parameters, depending on whether the cylinder radius R or the disk radius rd is used as the length scale. The study shows that the boundary curves are best correlated when presented in terms of the Reynolds number Ωrd2∕υ, aspect ratio H∕R, and cylinder-to-disk ratio R∕rd. The cylinder-to-disk ratio R∕rd up to 1.6 is found to have noticeable effect on vortex breakdown; this is attributed to the change of effective aspect ratio. The contours of streamline, angular momentum, and azimuthal vorticity are presented and compared with those of whole bottom-wall rotation.

Topology of vortex breakdown bubbles in a cylinder with a rotating bottom and a free surface

2001 ◽  
Vol 428 ◽  
pp. 133-148 ◽  
Author(s):  
MORTEN BRØNS ◽  
LARS K. VOIGT ◽  
JENS N. SØRENSEN
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Hopf Bifurcation ◽  
Numerical Methods ◽  
Aspect Ratio ◽  
Vortex Breakdown ◽  
Stability Limit ◽  
Similarities And Differences ◽  
The Stability ◽  
Two Parameters

The flow patterns in the steady, viscous flow in a cylinder with a rotating bottom and a free surface are investigated by a combination of topological and numerical methods. Assuming the flow is axisymmetric, we derive a list of possible bifurcations of streamline structures on varying two parameters, the Reynolds number and the aspect ratio of the cylinder. Using this theory we systematically perform numerical simulations to obtain the bifurcation diagram. The stability limit for steady flow is found and established as a Hopf bifurcation. We compare with the experiments by Spohn, Mory & Hopfinger (1993) and find both similarities and differences.

Numerical study of axisymmetric vortex breakdown in an annulus

1996 ◽  
Vol 118 (1-4) ◽  
pp. 79-95 ◽  
Author(s):  
N. Tsitverblit ◽  
E. Kit
Keyword(s):  
Vortex Breakdown ◽  
Numerical Study ◽  
Axisymmetric Vortex
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