Numerical Computations of the Flow in Curved Ducts

1975 ◽  
Vol 26 (3) ◽  
pp. 219-228 ◽  
Author(s):  
V S Pratap ◽  
D B Spalding
Keyword(s):  
Experimental Data ◽  
Kinetic Energy ◽  
Differential Equations ◽  
Dissipation Rate ◽  
Numerical Scheme ◽  
Pressure Field ◽  
The Other ◽  
Curved Duct ◽  
Flow Situation ◽  
Curved Ducts

SummaryThe paper describes the application of a recently developed numerical scheme to the computation of the flow in a curved duct. The flow situation is partially-parabolic in nature as there are significant elliptic effects, which are transmitted through the pressure field. The turbulence model used comprises two differential equations, one for the kinetic energy of turbulence and the other for its dissipation rate. It has been observed that the predictions using the new procedure agree very satisfactorily with the experimental data. Comparisons are also made with the predictions of a fully-parabolic calculation procedure.

Numerical Computation of Flow in Rotating Ducts

1977 ◽  
Vol 99 (1) ◽  
pp. 148-153 ◽  
Author(s):  
A. K. Majumdar ◽  
V. S. Pratap ◽  
D. B. Spalding
Keyword(s):  
Experimental Data ◽  
Kinetic Energy ◽  
Finite Difference ◽  
Numerical Computation ◽  
Cross Section ◽  
Dissipation Rate ◽  
Rectangular Cross Section ◽  
Longitudinal Direction ◽  
The Other ◽  
Constant Area

A finite-difference procedure is employed to predict the turbulent flow in ducts of rectangular cross-section, rotating about an axis normal to the longitudinal direction. The flows were treated as “parabolic” and the turbulence model used involved the solution of two differential equations, one for the kinetic energy of the turbulence and the other for its dissipation rate. Agreement with experimental data is good for a constant-area duct at low rotation, but less satisfactory for a divergent duct at larger rotation. It is argued that a “partially-parabolic” procedure will be needed to predict the latter flow correctly.

Prediction of turbulent flow in curved pipes

1975 ◽  
Vol 67 (3) ◽  
pp. 583-595 ◽  
Author(s):  
S. V. Patankar ◽  
V. S. Pratap ◽  
D. B. Spalding
Keyword(s):  
Experimental Data ◽  
Kinetic Energy ◽  
Finite Difference ◽  
Turbulent Flow ◽  
Dissipation Rate ◽  
The Other ◽  
Experimental Measurements ◽  
Curved Pipes ◽  
Developing Flow ◽  
Total Velocity

A finite-difference procedure is employed to predict the development of turbulent flow in curved pipes. The turbulence model used involves the solution of two differential equations, one for the kinetic energy of the turbulence and the other for its dissipation rate. The predicted total-velocity contours for the developing flow in a 180° bend are compared with the experimental data. Predictions of fully developed velocity profiles for long helically wound pipes are also presented and compared with experimental measurements.

Numerical Simulation of Flow on Stepped Spillway Combined with Wide Tailing Piers and Stilling Basin

2012 ◽  
Vol 170-173 ◽  
pp. 2047-2050
Author(s):  
W.L. Wei ◽  
B. Lv ◽  
Y.L. Liu ◽  
X.F. Yang
Keyword(s):  
Velocity Field ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Pressure Field ◽  
Free Water ◽  
Energy Dissipation Rate ◽  
Turbulence Kinetic Energy ◽  
Physical Parameters ◽  
Stepped Spillway ◽  
Two Phase

In this paper, a two-phase flow model combined with the Realizable k–ε turbulence model was used to simulate hydraulic characteristics of two-type dissipaters: the stepped spillway combined with stilling pool and the stepped spillway combined with wide tailing pier and stilling pool. The distributions of physical parameters, such as velocity field, pressure field, turbulence kinetic energy and turbulence dissipation rate were obtained. The grid was generated by using the regional division method, the unstructured grids used for the irregular and complex parts and the structured grids for the regular and simple parts, and the grid density is arranged according to the flow gradient size. The finite volume method was adopted to discretized the control equations; and the VOF method was adopted to deal with the free water surface; and the PISO algorithm was used to solve the velocity and pressure coupling equations. A comparative analysis of the two energy-dissipators in the velocity field, pressure field, turbulence kinetic energy and turbulence kinetic energy dissipation rate shows that the dissipation of overflow for a stepped spillway together with wide tailing piers and a stilling pool jointing energy dissipator is better than that with pier situation.

scholarly journals Overview of two deterministic modelings for prompt emission in fission

2021 ◽  
Vol 256 ◽  
pp. 00017
Author(s):  
Anabella Tudora
Keyword(s):  
Experimental Data ◽  
Kinetic Energy ◽  
Excitation Energy ◽  
The Other ◽  
New Method ◽  
Total Kinetic Energy ◽  
Γ Ray ◽  
Total Excitation Energy ◽  
The University ◽  
Prompt Emission

Two models with a deterministic treatment of prompt emission in fission were developed at the University of Bucharest. Both models work with the same ranges of initial fragments and total kinetic energy and they use the same partition of the total excitation energy at full acceleration based on modelling at scission. The main difference between these modelings regards the prompt emission treatment itself. I.e. the Point-by-Point (PbP) model uses a global treatment of sequential emission while the other modeling is based on an event-by-event treatment of sequential emission. Both models are submitted to a rigorous validation. This paper focuses on model results of different prompt γ-ray quantities, which describe very well the existing experimental data. A new method to calculate prompt γ-ray spectra, including a global treatment based on the distribution of prompt γ-ray energy per quanta, is proposed.

Similarity Solutions for Plane and Radial Jets Using a k-ε Turbulence Model

1985 ◽  
Vol 107 (1) ◽  
pp. 79-85 ◽  
Author(s):  
A. J. Paullay ◽  
R. E. Melnik ◽  
A. Rubel ◽  
S. Rudman ◽  
M. J. Siclari
Keyword(s):  
Growth Rate ◽  
Kinetic Energy ◽  
Differential Equations ◽  
Turbulence Model ◽  
Dissipation Rate ◽  
Eddy Viscosity ◽  
Similarity Solutions ◽  
Entrainment Velocity ◽  
Velocity Decay ◽  
Self Similar

When the eddy viscosity is defined by the standard k-ε turbulence model, the equations governing self-similar incompressible plane and radial jets have a solution that is not analytic at the jet edge. A transformation that stretches the similarity variable simplifies the defining set of ordinary differential equations and makes them amenable to efficient numerical integration. Highly resolved solutions for the velocity, turbulent kinetic energy and dissipation rate profiles are tabulated and entrainment, velocity decay rate and growth rate are determined. The growth rate differs by 6 percent from a parabolic marching asymptotic solution to the full partial differential equations.

Scaling of global properties of turbulence and skin friction in pipe and channel flows

2010 ◽  
Vol 652 ◽  
pp. 65-73 ◽  
Author(s):  
VICTOR YAKHOT ◽  
SEAN C. C. BAILEY ◽  
ALEXANDER J. SMITS
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Kinetic Energy ◽  
Friction Factor ◽  
Turbulent Kinetic Energy ◽  
Dissipation Rate ◽  
Friction Velocity ◽  
Scaling Law ◽  
Global Properties ◽  
Reynolds Number Dependence

Experimental data on the Reynolds number dependence of the area-averaged turbulent kinetic energy K and dissipation rate ℰ are presented. It is shown that while in the interval ReD > 105 the total kinetic energy scales with friction velocity (K/u*2 = const), a new scaling law K/〈U〉2 ∝ K/(u*2ReDθ) = const (θ ≈ 1/4) has been discovered in the interval ReD < 105. It is argued that this transition is responsible for the well-known change in the scaling behaviour of the friction factor observed in pipe and channels flows at ReD ≈ 105.

Dependence of the joint configuration on the dynamic immobility fulcrum

2019 ◽  
pp. 108-114
Author(s):  
A. D. Kozlov ◽  
Yu. P. Potekhina
Keyword(s):  
Kinetic Energy ◽  
Convex Surface ◽  
The Other ◽  
Concave Surface ◽  
Joint Configuration ◽  
Articular Surfaces

Although joints with synovial cavities and articular surfaces are very variable, they all have one common peculiarity. In most cases, one of the articular surfaces is concave, whereas the other one is convex. During the formation of a joint, the epiphysis, which has less kinetic energy during the movements in the joint, forms a convex surface, whereas large kinetic energy forms the epiphysis with a concave surface. Basing on this concept, the analysis of the structure of the joints, allows to determine forces involved into their formation, and to identify the general patterns of the formation of the skeleton.

scholarly journals New oscillation criteria for second-order neutral differential equations with distributed deviating arguments

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Osama Moaaz ◽  
Choonkil Park ◽  
Elmetwally M. Elabbasy ◽  
Waed Muhsin
Keyword(s):  
Differential Equations ◽  
Second Order ◽  
The Other ◽  
Riccati Transformation ◽  
Transformation Technique ◽  
Deviating Arguments ◽  
Neutral Differential Equations ◽  
Second Order Differential Equations ◽  
Continuous Delay ◽  
New Criteria

AbstractIn this work, we create new oscillation conditions for solutions of second-order differential equations with continuous delay. The new criteria were created based on Riccati transformation technique and comparison principles. Furthermore, we obtain iterative criteria that can be applied even when the other criteria fail. The results obtained in this paper improve and extend the relevant previous results as illustrated by examples.

scholarly journals Two and three pseudoscalar production in e+e− annihilation and their contributions to (g − 2)μ

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Wen Qin ◽  
Ling-Yun Dai ◽  
Jorge Portolés
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Pseudoscalar Meson ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Vacuum Polarization ◽  
Meson Production ◽  
The Other ◽  
Joint Analysis ◽  
The Standard Model

Abstract A coherent study of e+e− annihilation into two (π+π−, K+K−) and three (π+π−π0, π+π−η) pseudoscalar meson production is carried out within the framework of resonance chiral theory in energy region E ≲ 2 GeV. The work of [L.Y. Dai, J. Portolés, and O. Shekhovtsova, Phys. Rev. D88 (2013) 056001] is revisited with the latest experimental data and a joint analysis of two pseudoscalar meson production. Hence, we evaluate the lowest order hadronic vacuum polarization contributions of those two and three pseudoscalar processes to the anomalous magnetic moment of the muon. We also estimate some higher-order additions led by the same hadronic vacuum polarization. Combined with the other contributions from the standard model, the theoretical prediction differs still by (21.6 ± 7.4) × 10−10 (2.9σ) from the experimental value.

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