On the Friction Reducing Non-Newtonian Flow Around an Enclosed Disk

1974 ◽  
Vol 41 (1) ◽  
pp. 45-50 ◽  
Author(s):  
E. Bilgen ◽  
P. Vasseur
Keyword(s):  
Theoretical Analysis ◽  
Turbulent Flow ◽  
Boundary Layers ◽  
Flow Characteristics ◽  
Rotating Disk ◽  
Newtonian Flow ◽  
Dilute Polymer Solutions ◽  
Theoretical Predictions ◽  
Minimum Resistance ◽  
Good Agreement

The turbulent flow characteristics of non-Newtonian dilute polymer solutions around an enclosed rotating disk have been studied both theoretically and experimentally. In the theoretical analysis, the momentum equations of the boundary layers on both rotating disk and housing have been solved numerically using appropriate velocity profiles. It is shown that the theoretical predictions for minimum resistance conditions are in good agreement with the experimental results of this study and with those in the literature.

scholarly journals Numerical investigation of flow characteristics over stepped spillways

2020 ◽  
Author(s):  
Aytaç Güven ◽  
Ahmed Hussein Mahmood
Keyword(s):  
Numerical Model ◽  
Turbulent Flow ◽  
Flow Characteristics ◽  
Air Entrainment ◽  
Stepped Spillway ◽  
Stepped Spillways ◽  
Entrainment Velocity ◽  
Fluid Flow Characteristics ◽  
3D Package ◽  
Good Agreement

Abstract Spillways are constructed to evacuate the flood discharge safely not to let the flood wave overtop the dam body. There are different types of spillways, ogee type being the conventional one. Stepped spillway is an example of nonconventional spillways. The turbulent flow over stepped spillway was studied numerically by using the Flow-3D package. Different fluid flow characteristics such as longitudinal flow velocity, temperature distribution, density and chemical concentration can be well simulated by Flow-3D. In this study, the influence of slope changes on flow characteristics such as air entrainment, velocity distribution and dynamic pressures distribution over the stepped spillway was modelled by Flow-3D. The results from the numerical model were compared with the experimental study done by others in the literature. Two models of the stepped spillway with different discharge for each model was simulated. The turbulent flow in the experimental model was simulated by the Renormalized Group (RNG) turbulence scheme in the numerical model. A good agreement was achieved between the numerical results and the observed ones, which were exhibited in terms of graphics and statistical tables.

A Theoretical Analysis of the Bending into Cylindrical Dies of Metal Strips

1984 ◽  
Vol 198 (2) ◽  
pp. 99-108 ◽  
Author(s):  
T X Yu ◽  
W Johnson
Keyword(s):  
Theoretical Analysis ◽  
Metal Forming ◽  
Plastic Material ◽  
Forming Process ◽  
Rigid Plastic ◽  
Rigid Plastic Material ◽  
Punch Load ◽  
Theoretical Predictions ◽  
Metal Forming Process ◽  
Good Agreement

Based on experiments on the bending of metal strips into cylindrical dies using a semi-circular ended punch (1) a theoretical analysis of this metal forming process is presented to predict the punch load—punch travel characteristic and the clearance between the punch pole and the mid-point of the strip. Elastic/plastic and rigid/plastic material idealizations are employed, and the effect of friction between the strip and the die is also considered. The theoretical predictions show good agreement with the experimental results and are useful for designers.

Transitional flow between contra-rotating disks

1994 ◽  
Vol 281 ◽  
pp. 119-135 ◽  
Author(s):  
M. Kilic ◽  
X. Gan ◽  
J. M. Owen
Keyword(s):  
Boundary Layers ◽  
Cell Structure ◽  
Rotating Disk ◽  
Transitional Flow ◽  
Free Shear Layer ◽  
Rotating Disks ◽  
Double Transition ◽  
Type Flow ◽  
Radial Outflow ◽  
Good Agreement

This paper describes a combined computational and experimental study of the flow between contra-rotating disks for – 1 ≤ Γ ≤ 0 and Reϕ = 105, where Γ is the ratio of the speed of the slower disk to that of the faster one and Reϕ is the rotational Reynolds number of the faster disk. For Γ = 0, the rotor-stator case, laminar and turbulent computations and experimental measurements show that laminar Batchelor-type flow occurs: there is radial outflow in a boundary layer on the rotating disk, inflow on the stationary disk and a rotating core of fluid between. For Γ = – 1, the laminar computations produce Batchelor-type flow: there is radial outflow on both disks and inflow in a free shear layer in the mid-plane, on either side of which is a rotating core of fluid. The turbulent computations and the velocity measurements for Γ = – 1 show Stewartson-type flow: radial outflow occurs in laminar boundary layers on the disks and inflow occurs in a non-rotating turbulent core between the boundary layers. For intermediate values of Γ, transition from Batchelor-type flow to Stewartson-type flow is associated with a two-cell structure, the two-cells being separated by a streamline that stagnates on the slower disk; Batchelor-type flow occurs radially outward of the stagnation point and Stewartson-type flow radially inward. The turbulent computations are mainly in good agreement with the measured velocities for Γ = 0 and Γ = – 1, where either Batchelor-type flow or Stewartson-type flow occurs; there is less good agreement at intermediate values of Γ, particularly for Γ = – 0.4 where the double transition of Batchelor-type flow to Stewartson-type flow and laminar to turbulent flow occurs in the two-cell structure.

scholarly journals A theoretical analysis of the semileptonic decays $$\eta ^{(\prime )}\rightarrow \pi ^0l^+l^-$$ and $$\eta ^\prime \rightarrow \eta l^+l^-$$

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Rafel Escribano ◽  
Emilio Royo
Keyword(s):  
Theoretical Analysis ◽  
Semileptonic Decays ◽  
Coupling Constants ◽  
Energy Spectra ◽  
Radiative Decays ◽  
Vector Meson Dominance ◽  
Decay Widths ◽  
Theoretical Predictions ◽  
First Time ◽  
Good Agreement

AbstractA complete theoretical analysis of the C- conserving semileptonic decays $$\eta ^{(\prime )}\rightarrow \pi ^0l^+l^-$$ η ( ′ ) → π 0 l + l - and $$\eta ^\prime \rightarrow \eta l^+l^-$$ η ′ → η l + l - ($$l=e$$ l = e or $$\mu $$ μ ) is carried out within the framework of the Vector Meson Dominance (VMD) model. An existing phenomenological model is used to parametrise the VMD coupling constants and the associated numerical values are obtained from an optimisation fit to $$V\rightarrow P\gamma $$ V → P γ and $$P\rightarrow V\gamma $$ P → V γ radiative decays ($$V=\rho ^0$$ V = ρ 0 , $$\omega $$ ω , $$\phi $$ ϕ and $$P=\pi ^0$$ P = π 0 , $$\eta $$ η , $$\eta ^{\prime }$$ η ′ ). The decay widths and dilepton energy spectra for the two $$\eta \rightarrow \pi ^0l^+l^-$$ η → π 0 l + l - processes obtained using this approach are compared and found to be in good agreement with other results available in the published literature. Theoretical predictions for the four $$\eta ^{\prime }\rightarrow \pi ^0l^+l^-$$ η ′ → π 0 l + l - and $$\eta ^\prime \rightarrow \eta l^+l^-$$ η ′ → η l + l - decay widths and dilepton energy spectra are calculated and presented for the first time in this work.

Heat and mass transfer from rotating cones

1963 ◽  
Vol 17 (1) ◽  
pp. 105-112 ◽  
Author(s):  
C. L. Tien ◽  
D. T. Campbell
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Heat And Mass Transfer ◽  
Flow Characteristics ◽  
Sublimation Rate ◽  
Semi Empirical ◽  
Good Agreement

Heat transfer by convection from isothermal rotating cones is investigated experimentally by measuring the sublimation rate from naphthalene-coated cones and using the analogy between heat and mass transfer. Measurements are made for a range of conditions from entirely laminar flow to conditions when the outer 70% of the surface area is covered by turbulent flow. Mass-transfer measurements for laminar flow over cones of vertex angles 180°, 150°, 120° and 90° are in good agreement with the theoretical prediction. For turbulent flow, experimental results for cones of the above vertex angles also agree very well with the semi-empirical analogy calculations for the disk case. A different heat- and mass-transfer relationship with the rotational Reynolds number is observed in the measurements on the 60° cone, and is believed to be due to a change of flow characteristics. The instability and the transition of flows over different cone models are also discussed.

Research on Characteristics of Mercury Droplet Flow in Micro Acceleration Switch

2013 ◽  
Vol 562-565 ◽  
pp. 328-333
Author(s):  
Ting Ting Liu ◽  
Wei Su ◽  
Tao Yang ◽  
Bin Han ◽  
Chao Wang
Keyword(s):  
Contact Angle ◽  
Liquid Metal ◽  
Theoretical Analysis ◽  
Numerical Models ◽  
Flow Characteristics ◽  
Droplet Volume ◽  
Solid Contact ◽  
Droplet Flow ◽  
Contact Wear ◽  
Good Agreement

Unlike the solid-solid contact of traditional micro acceleration switch, liquid metal can be utilized to solve the disadvantage of solid-solid contact, such as contact wear and signal bounce. Liquid-metal micro switches have demonstrated no contact bounce, low switch-on time, low contact resistance, long life, and the capability to handle large currents. So the liquid-metal micro acceleration switches have attracted researcher’s attentions increasingly. To investigate the flow characteristics of mercury droplet in micro acceleration switch, this paper establishes numerical models of micro acceleration switch by using FLUENT. The effect of contact angle, droplet volume and temperature are discussed in this paper. Based on the VOF-CSF model of FLUENT, a serial of simulations were performed. The simulation results show that the influence of contact angle and droplet volume on flow characteristics is serious, and the influence of temperature is small. As compared with theoretical analysis, simulations are in good agreement with theoretical analysis.

Transport to a Rotating Disk in Turbulent Flow at High Prandtl or Schmidt Number

1973 ◽  
Vol 95 (4) ◽  
pp. 566-568 ◽  
Author(s):  
J. A. Paterson ◽  
R. Greif
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Mass Flux ◽  
Eddy Viscosity ◽  
Schmidt Number ◽  
Rotating Disk ◽  
Conservation Equations ◽  
High Schmidt Number ◽  
Number Problem ◽  
Good Agreement

The eddy viscosity distribution near the surface of a rotating disk is determined from an analysis of the basic conservation equations. The results are applied to the high Schmidt number problem and good agreement is obtained with experimental data for the mass flux.

Experimental Investigation of the Biaxial Load-Extension Properties of Plain, Weft-Knitted Fabrics

1977 ◽  
Vol 47 (4) ◽  
pp. 233-239 ◽  
Author(s):  
Brian M. Macrory ◽  
J. Roger Mccraith ◽  
A. B. McNamara
Keyword(s):  
Experimental Investigation ◽  
Theoretical Analysis ◽  
Experimental Results ◽  
Knitted Fabric ◽  
Knitted Fabrics ◽  
Test Instrument ◽  
Biaxial Load ◽  
Theoretical Predictions ◽  
End Use ◽  
Good Agreement

A test instrument is described which permits measurement of load and extension along the courses and wales of a knitted fabric as the latter is being extended in both directions simultaneously. The rates of extension may be chosen to deform the fabric in a variety of modes representative of end-use situations. Experimental results obtained for plain, weft-knitted fabrics using three different hosiery yarns are presented. Comparison is made with values predicted by the authors' theoretical analysis of the biaxially-loaded fabric configuration, and good agreement between the experimental results and the theoretical predictions is obtained.

A study of the slipstreams of high-speed passenger trains and freight trains

2008 ◽  
Vol 222 (2) ◽  
pp. 177-193 ◽  
Author(s):  
M Sterling ◽  
C J Baker ◽  
S C Jordan ◽  
T Johnson
Keyword(s):  
Experimental Data ◽  
Boundary Layers ◽  
High Speed ◽  
Flow Characteristics ◽  
Full Scale ◽  
Small Scale ◽  
Flow Features ◽  
Passenger Trains ◽  
Container Freight ◽  
Good Agreement

As the speeds of both passenger and freight trains increase, there is increasing concern that the unsteady gusts generated in train boundary layers and wakes will become more of for a risk to passengers waiting on platforms and for trackside workers. In addition, the demands of interoperability make this a problem of growing relevance to railway operators across Europe. A number of model scale and full-scale experiments have been carried out in recent years that have provided robust experimental data to quantify these flows. This paper considers all the available datasets for high-speed passenger trains and container freight trains, and in making a comparison between them, arrives at a number of conclusions concerning the characteristics of train slipstreams. It is concluded that the identification of a number of distinct flow regions in earlier work is generally valid and forms a useful framework for the consideration of the problem. The flow characteristics are different in each region, and, depending upon the train type, the measurement distance from the train and height above ground, the observed peak gusts for a train may occur at any time during the train passage or in its wake. It is also concluded that results obtained from measurements around small scale moving models are in good agreement with the full scale measurements and reproduce all the important flow features.

The Lubrication of Lightly Loaded Cylinders in Combined Rolling, Sliding, and Normal Motion—Part II: Experimental

1976 ◽  
Vol 98 (4) ◽  
pp. 517-522 ◽  
Author(s):  
P. H. Markho ◽  
D. Dowson
Keyword(s):  
Boundary Condition ◽  
Theoretical Analysis ◽  
High Speed ◽  
Squeeze Film ◽  
Theoretical Predictions ◽  
Good Agreement

This paper forms part of a wider investigation which includes the theoretical analysis given in Part I in addition to a study of the outlet cavitation boundary, using high-speed cine photography, reported elsewhere [4]. Pressure and some load measurements are presented which show good agreement with the theoretical predictions despite the well-known shortcomings of the Swift-Stieber boundary condition used in the analysis. Two sets of results have been included to cover the pure squeeze-film problem in addition to that of combined rolling, sliding and “normal” motion.

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