Laminar steady flow regimes of two-component dispersed systems. Vertical flows

1971 ◽  
Vol 3 (3) ◽  
pp. 35-41
Author(s):  
Yu. A. Buevich

2011 ◽  
Vol 8 (1) ◽  
pp. 143-152
Author(s):  
S.F. Khizbullina

The steady flow of anomalous thermoviscous liquid between the coaxial cylinders is considered. The inner cylinder rotates at a constant angular velocity while the outer cylinder is at rest. On the basis of numerical experiment various flow regimes depending on the parameter of viscosity temperature dependence are found.



1980 ◽  
Vol 102 (1) ◽  
pp. 104-111 ◽  
Author(s):  
T. Morel ◽  
M. Bohn

Placing two or more bluff-bodies in tandem is known to lead, in some cases, to configurations with relatively low overall drag. The present study concerns one particular case where two disks of unequal diameters, normal to the flow, are placed in tandem for the purpose of drag reduction. It shows that very significant drag reductions may be achieved by proper sizing of the disk diameters and of the gap between them. Placing a properly sized disk at an optimum distance ahead of a single reference disk can result in a configuration whose total drag is up to 81 percent lower than that of the reference disk alone. If the additional disk is placed behind into the near-wake of the reference disk, the drag of the two-disk configuration can be up to 70 percent lower than for the reference disk alone. Four different flow regimes have been identified, depending on the diameter ratio of the two disks, two with relatively steady flows and two with unsteady flows. The absolute drag minimum was found to occur in one of the two steady-flow regimes.



1969 ◽  
Vol 91 (1) ◽  
pp. 51-58 ◽  
Author(s):  
H. S. Yu ◽  
E. M. Sparrow

Two-component stratified flow in a horizontal rectangular duct has been investigated experimentally. The working fluids were a transparent white mineral oil and water, the viscosity ratio being approximately 30. The tests encompassed a variety of flow regimes including laminar-laminar, laminar-turbulent, and turbulent-turbulent. In addition, a variety of conditions at the interface between the component flows was encountered and investigated. The experimental results for flow and pressure drop are found to be quite insensitive to the shape of the interface and even to the presence of very small waves, when both flow components are laminar. This finding extends the range of validity of flat-interface laminar flow theory. The conditions for the existence of various flow regimes are quantitatively characterized. It was demonstrated that interfacial waves could occur even when both component flows were laminar, and that laminar and turbulent flows could coexist in the separate layers. Results from depth-probe surveys and photographic visualization of the flow are also presented.





1991 ◽  
Vol 113 (4) ◽  
pp. 574-578 ◽  
Author(s):  
V. C. Patel ◽  
J. Tyndall Chon ◽  
J. Y. Yoon

The boundary layer over a wavy wall and fully-developed flow in a duct with a wavy wall are considered. Numerical solutions of the Navier-Stokes equations have been obtained to provide insights into the various steady flow regimes that are possible, and to illustrate the nuances of predicting flows containing multiple separation and reattachment points.



2019 ◽  
Vol 4 (3) ◽  
Author(s):  
A. Mariotti ◽  
C. Galletti ◽  
E. Brunazzi ◽  
M. V. Salvetti


1985 ◽  
Vol 107 (3) ◽  
pp. 413-420 ◽  
Author(s):  
A. F. Bicen ◽  
C. Vafidis ◽  
J. H. Whitelaw

An experimental investigation of the airflow through various axisymmetric intake ports of a motored reciprocating engine is reported. Detailed velocity field measurements obtained by laser Doppler anemometry and for steady and various unsteady flow conditions are presented together with valve discharge coefficients from steady flow tests. The results showed that over the lift range investigated the valve flow exhibited various regimes indicated by the changes in the flow pattern at the valve exit. With a 45-deg seat angle, four regimes were identified compared to three in the case of a 60-deg valve. The overall behavior of the 45-deg valve, however, was found to be generally better. Rounding of the edges of the 45-deg valve reduced the number of flow regimes to two with marked improvements on discharge coefficient. The flow angle at the valve exit depended less on the flow regimes and more on the cylinder confinement, in the absence of which the transition from one regime to another was delayed. The mean flow pattern at the valve exit was found to be insensitive to flow unsteadiness, piston confinement and valve operation and thus could be predicted with reasonable accuracy from steady flow tests. The in-cylinder flow characteristics were also insensitive to valve operation, but strongly depended on piston interaction, flow unsteadiness and residual effects from the previous cycle.



Author(s):  
Michael M. Bernitsas ◽  
Kamaldev Raghavan

Vortex Induced Vibration (VIV) of a circular cylinder in a steady flow is reduced using distributed surface roughness. VIV reduction is needed in numerous applications where VIV is destructive. Roughness is distributed to the surface of the cylinder in the form of sandpaper strips to achieve three goals: (1) Trip separation in a controlled manner so that some uncertainties are removed and the flow becomes more predictable. (2) Reduce spanwise correlation, which is strongly linked to VIV. (3) Select roughness grit size to achieve the first goal without energizing too much the boundary layer, which would induce higher vorticity and circulation, and consequently lift. Our experiments show that it is possible to reduce VIV amplitude and synchronization range. More tests are needed to achieve full suppression. Our experiments are conducted in the TrSL2 and TrSL3 flow regimes.



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