scholarly journals Numerical Analysis of Three-Dimensional Turbulent Flow in 180.DEG.-Bent Tube by Low-Reynolds-Number Turbulent Models.

1995 ◽  
Vol 61 (585) ◽  
pp. 1707-1713 ◽  
Author(s):  
Hitoshi Sugiyama ◽  
Mitsunobu Akiyama ◽  
Yutaka Kikuchi
Keyword(s):  
Reynolds Number ◽  
Numerical Analysis ◽  
Turbulent Flow ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Low Reynolds ◽  
Turbulent Models

Prediction of Three-Dimensional Developing Turbulent Flow in a Square Duct With an Anisotropic Low-Reynolds-Number k-ε Model

1991 ◽  
Vol 113 (4) ◽  
pp. 608-615 ◽  
Author(s):  
Hyon Kook Myong ◽  
Toshio Kobayashi
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Reynolds Shear Stress ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Complex Flow ◽  
Square Duct ◽  
Low Reynolds

Three-dimensional developing turbulent flow in a square duct involving turbulence-driven secondary motion is numerically predicted with an anisotropic low-Reynolds-number k-ε turbulence model. Special attention has been given to both regions close to the wall and the corner, which are known to influence the characteristics of secondary flow a great deal. Hence, the no-slip boundary condition at the wall is directly used in place of the common wall function approach. The resulting set of equations simplified only by the boundary layer assumption are first compared with previous algebraic stress models, and solved with a forward marching numerical procedure for three-dimensional shear layers. Typical predicted quantities such as mean axial and secondary velocities, friction coefficients, turbulent kinetic energy, and Reynolds shear stress are compared with available experimental data. These results indicate that the present anisotropic k-ε turbulence model performs quite well for this complex flow field.

Numerical Analysis of an Actively Cooled Low-Reynolds-Number Hypersonic Diffuser

2019 ◽  
Vol 33 (1) ◽  
pp. 32-48 ◽  
Author(s):  
Andrew J. Brune ◽  
Serhat Hosder ◽  
David Campbell ◽  
Stefano Gulli ◽  
Luca Maddalena
Keyword(s):  
Reynolds Number ◽  
Numerical Analysis ◽  
Low Reynolds Number ◽  
Low Reynolds

Application of Non-Linear k–ω Model to the Turbulent Flow Inside a Sharp U-Bend

2000 ◽  
Author(s):  
B. Song ◽  
R. S. Amano
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Higher Order ◽  
Shear Stresses ◽  
Complex Flow ◽  
Streamline Curvature ◽  
Non Linear ◽  
Low Reynolds

Simulation of the complex flow inside a sharp U-bend needs both refined turbulence models and higher order numerical discretization schemes. In the present study, a nonlinear low-Reynolds number (low-Re) k–ω model including the cubic terms was employed to predict the turbulent flow through a square cross-sectioned U-bend with a sharp curvature, Rc/D = 0.65. In the turbulence model employed for the present study, the cubic terms are incorporated to represent the effect of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and shear stresses. In order to accurately predict such complex flowfields, a higher-order bounded interpolation scheme (Song, et al., 1999) has been used to discretize all the transport equations. The calculated results by using both the non-linear k–ω model and the linear low-Reynolds number k–ε model (Launder and Sharma, 1974) have been compared with experimental data. It is shown that the present model produces satisfactory predictions of the flow development inside the sharp U-bend and well captures the characteristics of the turbulence anisotropy within the duct core region and wall sub-layer.

Non-Spheric Colloidal Suspensions in Three-Dimensional Space

1997 ◽  
Vol 08 (04) ◽  
pp. 985-997 ◽  
Author(s):  
Dewei Qi
Keyword(s):  
Reynolds Number ◽  
Dimensional Space ◽  
Low Reynolds Number ◽  
Paper Industry ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Solid Particles ◽  
Spherical Particles ◽  
Dynamic Simulations ◽  
Low Reynolds

The translation and rotation of non-spherical particles, such as ellipsoidal, cylindric or disk-like pigment particles, in a Couette flow system similar to a blade coating system in the paper industry6 have been successfully simulated by using the lattice-Boltzmann method combined with Newtonian dynamic simulations. Hydrodynamic forces and torques are obtained by the use of boundary conditions which match the moving surface of solid particles. Then Euler equations have been integrated to include three-dimensional rotations of the suspensions by using four quaternion parameters as generalized coordinates. The three-dimensional rotations have been clearly observed. Consequently, the motion of the particles suspended in fluids of both low-Reynolds-number and finite-Reynolds-number, up to several hundreds, has been studied. It appears that the 3D translation and rotation of the non-spherical particles are more clearly observed in a high-Reynolds-number fluid than in a low-Reynolds-number fluid.

The motion of rigid particles in a shear flow at low Reynolds number

1962 ◽  
Vol 14 (2) ◽  
pp. 284-304 ◽  
Author(s):  
F. P. Bretherton
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Body Of Revolution ◽  
Rigid Particles ◽  
Unidirectional Flow ◽  
Uniform Shear ◽  
Ellipsoid Of Revolution ◽  
Low Reynolds ◽  
Bounding Surfaces

According to Jeffery (1923) the axis of an isolated rigid neutrally buoyant ellipsoid of revolution in a uniform simple shear at low Reynolds number moves in one of a family of closed periodic orbits, the centre of the particle moving with the velocity of the undisturbed fluid at that point. The present work is a theoretical investigation of how far the orbit of a particle of more general shape in a non-uniform shear in the presence of rigid boundaries may be expected to be qualitatively similar. Inertial and non-Newtonian effects are entirely neglected.The orientation of the axis of almost any body of revolution is a periodic function of time in any unidirectional flow, and also in a Couette viscometer. This is also true if there is a gravitational force on the particle in the direction of the streamlines. There is no lateral drift. On the other hand, certain extreme shapes, including some bodies of revolution, will assume one of two orientations and migrate to the bounding surfaces or to the centre of the flow. In any constant slightly three-dimensional uniform shear any body of revolution will ultimately assume a preferred orientation.

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