A model for evaluating the particle penetration efficiency in a ninety-degree bend with a circular-cross section in laminar and turbulent flow regions

2017 ◽  
Vol 305 ◽  
pp. 771-781 ◽  
Author(s):  
X.C. Cong ◽  
G.S. Yang ◽  
J.H. Qu ◽  
J.J. Zhao
Keyword(s):  
Turbulent Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Particle Penetration ◽  
Laminar And Turbulent Flow

scholarly journals Accessing the Influence of Hess-Murray Law on Suspension Flow through Ramified Structures

2013 ◽  
Vol 334-335 ◽  
pp. 322-328 ◽  
Author(s):  
Ana Serrenho ◽  
Antonio F. Miguel
Keyword(s):  
Fluid Flow ◽  
Turbulent Flow ◽  
Cross Section ◽  
Particle Transport ◽  
Flow Resistance ◽  
Suspension Flow ◽  
Similar Performance ◽  
Particle Penetration ◽  
Laminar And Turbulent Flow ◽  
Flow Through

The present study focuses on fluid flow and particle transport in symmetric T-shaped structures formed by tubes with circular and square cross-section. The performances of optimized structures (i.e., structures designed based on constructal allometric laws for minimum flow resistance) and not optimized structures were studied. Flow resistance and particle penetration efficiency were studied both for laminar and turbulent flow regimes, and for micrometer and submicrometer particles. Optimized structures have been proven to perform better for fluid flow but they have a similar performance for particle transport.

Flow in Rotating Straight Pipes of Circular Cross Section

1971 ◽  
Vol 93 (3) ◽  
pp. 383-394 ◽  
Author(s):  
H. Ito¯ ◽  
K. Nanbu
Keyword(s):  
Friction Factor ◽  
Cross Section ◽  
Circular Cross Section ◽  
Constant Angular Velocity ◽  
Smooth Wall ◽  
Good Qualitative Agreement ◽  
Fully Developed Flow ◽  
Number Range ◽  
Friction Factors ◽  
Laminar And Turbulent Flow

The friction factor for fully developed flow in smooth wall straight pipes of circular cross section rotating at a constant angular velocity about an axis perpendicular to its own has been measured in the Reynolds number range from 20 to 60,000. Empirical equations for friction factors for small values of RΩ/R were presented for both laminar and turbulent flow. In the case of laminar flow, an approximate analysis based on the assumption that the flow consists of a frictionless central core surrounded by a boundary layer was presented. The results were in good qualitative agreement with experimental results in regard to the friction factor, velocity distribution in the plane of symmetry and pressure distribution along the circumferential wall of the pipe.

Bottom shear stress in unsteady sewer flow

2006 ◽  
Vol 54 (6-7) ◽  
pp. 93-100 ◽  
Author(s):  
V. Bareš ◽  
J. Jirák ◽  
J. Pollert
Keyword(s):  
Shear Stress ◽  
Turbulent Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Distribution Data ◽  
Time Lags ◽  
Bottom Shear Stress ◽  
Flow Conditions ◽  
Turbulent Layer ◽  
Venant Equation

The properties of unsteady open-channel turbulent flow were theoretically and experimentally investigated in a circular cross section channel with fixed sediment deposits. Velocity and turbulence distribution data were obtained using an ultrasonic velocity profiler (UVP). Different uniform flow conditions and triangular-shaped hydrographs were analysed. The hydrograph analysis revealed a dynamic wave behaviour, where the time lags of mean cross section velocity, friction velocity, discharge and flow depth were all evident. The bottom shear stress dynamic behaviour was estimated using four different approaches. Measurements of the velocity distribution in the inner region of the turbulent layer and of the Reynolds stress distribution in the turbulent flow provided the analysed data sets of the bottom shear stress. Furthermore, based on the Saint Venant equation, the bottom shear stress time behaviour was studied using both the kinematic and the dynamic flow principles. The dynamic values of the bottom shear stress were compared with those for the steady flow conditions. It is evident that bottom shear stress varies along the generated flood hydrograph and its variation is the function of the flow unsteadiness. Moreover, the kinematic flow principle is not an adequate type of approximation for presented flow conditions.

Mixing of Gases and Miscible Liquids in a T-Junction

2017 ◽  
Author(s):  
Wangshu Wei ◽  
Charles N. Haas ◽  
Bakhtier Farouk
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Species Conservation ◽  
Circular Cross Section ◽  
Flow Fields ◽  
Transport Processes ◽  
Water Mixture ◽  
Turbulent Schmidt Number ◽  
Laminar And Turbulent Flow ◽  
Miscible Liquids

The transport processes in the mixing of either two gases or two miscible liquids in a T-junction are investigated numerically. Both laminar and turbulent flow fields are considered. The 3-D time-dependent flow fields are calculated for the T-junction (of two circular cross-section pipes that meet orthogonally at the junction). For turbulent flow regimes, the large eddy simulation (LES) technique is employed. In the 3-D mathematical model, the transport of species is described by the species conservation equations. The results obtained by the numerical simulations are verified with available experimental data in the literature for methane-air mixing in a T-junction. The effect of variation of the value of turbulent Schmidt number is investigated. Temporal concentration fluctuations are calculated and are compared to the spatial fluctuations. The mixing of two miscible liquids (water and peracetic acid-water mixture) are also investigated for the laminar and turbulent flow fields (using the LES technique). The mixing behavior of two gases and two miscible liquids in a T-junction are compared and contrasted for both laminar and turbulent flows.

Experimental Studies of Turbulent Flow in a Porous Circular Tube With Uniform Fluid Injection Through the Tube Wall

1966 ◽  
Vol 33 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Reuben M. Olson ◽  
E. R. G. Eckert
Keyword(s):  
Turbulent Flow ◽  
Cross Section ◽  
Mass Velocity ◽  
Tube Wall ◽  
Experimental Studies ◽  
Circular Cross Section ◽  
Axial Position ◽  
Tube Length ◽  
Injection Velocity ◽  
Porous Tube

Fully developed turbulent flow of air at Re = 28,000 to 82,000 entered a porous tube with circular cross section. Air was injected uniformly through the tube wall for 18 diameters at various ratios of mass velocity through the tube wall to the average mass velocity at the entrance cross section of the tube, ranging from 0.00246 to 0.0584. Tests were also made with zero entrance velocity at the upstream end of the porous tube so that the flow developed in the tube exclusively as a result of the uniform mass injection through the tube wall. Most of the change in the shape of the velocity profiles, in the internal and wall shear, in the momentum flux factor, and in the friction factor occurred within the first 10 to 12 diameters of the tube length. Some changes even persisted further downstream, caused by the fact that mass is continuously injected along the porous tube. The parameters mentioned above, however, become independent of axial position for normalized distances downstream from the entrance cross section larger than x/D = 10 to 12, when they are considered as function of the ratio of injection velocity to average main flow velocity at the specific axial location. Eddy diffusivity values agreed in this presentation reasonably with the results of measurements in turbulent tube flow without injection. Normalized friction factors agreed with values measured in external flow. Properly normalized velocity defect profiles with injection agreed with those for flow without injection.

scholarly journals Hydraulic resistances experimental and field studies of supply canals and pumping stations structures

2021 ◽  
Vol 264 ◽  
pp. 03075
Author(s):  
Bakhtiyor Uralov ◽  
Marina Li ◽  
Eshmatboy Qalqonov ◽  
Zokhidjon Ishankulov ◽  
Makhfuz Akhmadi ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Pressure Head ◽  
Field Studies ◽  
Calculation Methods ◽  
Flat Bottom ◽  
Plane Parallel ◽  
Pumping Stations ◽  
Large Width

Currently, many authors have studied the uniform axisymmetric pressure head laminar and turbulent movement of water in hydraulic smooth and rough (with uniform roughness) pipes of circular cross-section. The results obtained in the study of a plane-parallel turbulent flow in pressure canals allows here only to outline the structure of the corresponding dependencies and to clarify the simplest case of unpressurized fluid movement, when this movement can also be reduced to plane-parallel or, in other words, to movement in a canal of infinitely large width with a flat bottom. In all other cases, the only way to solve the problem is an experiment. The construction of numerous free-flow watercourses and machine canals of pumping stations requires scientifically based calculation methods.

scholarly journals The influence of secondary flow in a two-phase gas-solid system in straight channels with a non-circular cross-section

2016 ◽  
Vol 20 (suppl. 5) ◽  
pp. 1419-1434
Author(s):  
Sasa Milanovic ◽  
Milos Jovanovic ◽  
Boban Nikolic ◽  
Vladislav Blagojevic
Keyword(s):  
Turbulent Flow ◽  
Secondary Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Channel Cross Section ◽  
Two Phase ◽  
Cross Sectional ◽  
Specific Flow ◽  
Sectional Plane ◽  
The Cross

The paper considers two-phase gas-solid turbulent flow of pneumatic transport in straight horizontal channels with a non-circular cross-section. During turbulent flow, a specific flow phenomenon, known as secondary flow, occurs in these channels in the cross-sectional plane. The existence of strong temperature gradients in the cross-sectional plane of the channel or the cases of curved channels result in the appearance of the secondary flow of the first kind. However, in straight channels with a non-circular cross-section, in the developed turbulent flow mode, a secondary flow, known as Prandtl?s secondary flow of the second kind, is induced. The paper presents a numerical simulation of a developed two-phase turbulent flow by using the PHOENICS 3.3.1 software package. Reynolds stress model was used to model the turbulence. The paper provides the data on the changes in turbulent stresses in the channel cross-section as well as the velocities of solid particles transported along the channel.

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