Reattachment Flow Issuing from a Finite Width Nozzle : Report 2, Effects of Initial Turbulence Intensity

Nozaki, Tsutomu; Hatta, Keiji; Sato, Norihide; Matsumura, Hirohisa

doi:10.1299/jsme1958.24.363

Cited by 17 publications

(2 citation statements)

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“…Johnston [9] based on the theory of the previous scientists, experimentally studied the offset jet and obtained the profile of flow and velocity for different depth waters. Nozaki et al [10] obtained the results of experiments on the impingement point, the distribution of dynamic pressure on the wall, the jet centerline path and the damping of the maximum velocity of the jet axis in the converging zone. Hoch and Jiji [11] in 1981 investigated the jet path, the jet-to-wall impingement point, the wall pressure distribution, and damping of the maximum velocity of jet axis velocity, as well as the effect of the free secondary flow velocity on the impingement point.…”

Section: Figure 1 Schematic Design Of Offset Jet Flowmentioning

confidence: 99%

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Boroomand

Mohammadi

2019

Civ Eng J

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In the case in which relatively low thickness and high-velocity flow enter into the lower velocity fluid, the resulting interference field of these two flows is called the jet. This phenomenon is the dominant output of power plants and some of the dams. The jets can be divided into two categories of free jets and confined jets, caused by the distance from the discharge to limited boundaries points. The offset jet is a type of confined jet in which both free surface and wall boundaries are near the diffusion location. The jet flow due to the extreme curvature in the main flow path and the proximal portion of this flow with solid boundaries have characteristics that make it difficult to solve with simple turbulence models.In this research, the offset jet phenomenon and related issues have been investigated. For this purpose, the offset jet flow pattern and probable factors in the complexity of this model have been simulated using Fluent software which analyses fluid flow in a two dimensional and three dimensional finite volume method. The simulation of offset jet flow pattern has been performed with a focus on investigating different models of turbulence k-ε, also boundary conditions, various wall functions and other effective coefficients in the numerical model and the model results compared with test case data findings and validating results, the necessary approaches in numerical simulation of this phenomenon for using in the next stages had been taken.

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Section: Figure 1 Schematic Design Of Offset Jet Flowmentioning

confidence: 99%

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Boroomand

Mohammadi

2019

Civ Eng J

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“…However reasonable agreement was seen for large offset ratios. Nozaki et al (1981) studied the influence of initial turbulence intensity upon the flow field of an offset jet. Furthermore, the influence of the aspect ratio of offset jet was evaluated by Nozaki (1983).…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Nozzle Geometry Effect on Turbulent 3-D Water Offset Jet Flows

Aliha¹,

Afshin²,

Farhanieh³

2016

JAFM

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Using the Yang-Shih low Reynolds k-ε turbulence model, the mean flow field of a turbulent offset jet issuing from a long circular pipe was numerically investigated. The experimental results were used to verify the numerical results such as decay rate of streamwise velocity, locus of maximum streamwise velocity, jet half width in the wall normal and lateral directions, and jet velocity profiles. The present study focused attention on the influence of nozzle geometry on the evolution of a 3D incompressible turbulent offset jet. Circular, square-shaped, and rectangular nozzles were considered here. A comparison between the mean flow characteristics of offset jets issuing from circular and square-shaped nozzles, which had equal area and mean exit velocity, were made numerically. Moreover, the effect of aspect ratio of rectangular nozzles on the main features of the flow was investigated. It was shown that the spread rate, flow entrainment, and mixing rate of an offset jet issuing from circular nozzle are lower than square-shaped one. In addition, it was demonstrated that the aspect ratio of the rectangular nozzles only affects the mean flow field of the offset jet in the near field (up to 15 times greater than equivalent diameter of the nozzles). Furthermore, other parameters including the wall shear stress, flow entrainment and the length of potential core were also investigated.

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Numerical Study of a Turbulent Offset Jet Flow

Assoudi

Habli

Saïd

et al. 2015

Lecture Notes in Mechanical Engineering

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Sixth Conference on Design and Modeling of Mechanical Systems (CMSM 2015), Hammamet, TUNISIA, MAR 23-25, 2015International audienceA dynamic study of the mean flow behavior of a three-dimensional turbulent offset jet issuing into a quiescent ambient is presented. The flow is characterized by a longitudinal variation of curvature, skewed impingement onto a flat surface, a recirculating region, and the development of a wall jet region. A numerical simulation is used, by means of the finite volume method with the second order turbulent closure model: the Reynolds stress Model (RSM), to investigate the influence of certain parameters such as jet discharge height and the geometric nozzle. Flow structure is described in the preimpingement, recirculation and impingement regions. Interdependence is shown among the offset height (h) and the geometric nozzle (plane jet and circular jet). The obtained results are presented in terms of the jet dimensionless velocity distribution, maximum velocity decay and vectors velocity of the flow. The jet decay is presented. The recirculation region is fed by a relatively strong backflow for the reported high offset height and it is shown that the reattachment point depends strongly with the jet form and the offset height

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Reattachment Flow Issuing from a Finite Width Nozzle : Report 2, Effects of Initial Turbulence Intensity

Cited by 17 publications

References 0 publications

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Numerical Investigation of Nozzle Geometry Effect on Turbulent 3-D Water Offset Jet Flows

Numerical Study of a Turbulent Offset Jet Flow

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