Numerical study of transition in a cylindrical pipe flow

2004 ◽  
Vol 9 (6) ◽  
pp. 661-668 ◽  
Author(s):  
J Chen ◽  
G.X Cui ◽  
C.X Xu ◽  
Z.S Zhang ◽  
F.T.M Nieuwstadt
Keyword(s):  
Pipe Flow ◽  
Numerical Study ◽  
Cylindrical Pipe

Cartesian Based Finite Volume Formulation for LES of Mixed Convection in a Vertical Turbulent Pipe Flow

2002 ◽  
Author(s):  
Xiaofeng Xu ◽  
Joon Sang Lee ◽  
R. H. Pletcher
Keyword(s):  
Finite Volume ◽  
Pipe Flow ◽  
Stokes Equations ◽  
Numerical Study ◽  
Turbulent Pipe Flow ◽  
Shear Stresses ◽  
Turbulent Heat ◽  
Subgrid Scale ◽  
Wall Boundary Conditions ◽  
High Heating

A numerical study was performed to investigate the effects of heating and buoyancy on the turbulent structures and transport in turbulent pipe flow. Isoflux wall boundary conditions with low and high heating were imposed. The compressible filtered Navier-Stokes equations were solved using a second order accurate finite volume method. Low Mach number preconditioning was used to enable the compressible code to work efficiently at low Mach numbers. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. The results showed that strong heating caused distortions of the flow structures resulting in reduction of turbulent intensities, shear stresses, and turbulent heat flux, particularly near the wall. The effect of heating was to raise the mean streamwise velocity in the central region and reduce the velocity near the wall resulting in velocity distributions that resembled laminar profiles for the high heating case.

Heat Transfer Enhancement in Pipe Flow Problems of a Magnetic Fluid

2007 ◽  
Author(s):  
P. N. Kaloni ◽  
F. Lin ◽  
G. W. Rankin
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Internal Rotation ◽  
Magnetic Fluid ◽  
Pipe Flow ◽  
Magnetic Particles ◽  
Transfer Enhancement ◽  
Cylindrical Pipe ◽  
Flow Problems ◽  
Dissipation Term

Analytical solutions are presented for the temperature distribution and heat transfer coefficient in the forced convection of a magnetic fluid in cylindrical pipe flow. The theory of a ferro-fluid with internal rotation of magnetic particles is employed. Effects of the conventional dissipation term along with the dissipation reflecting the effect of internal rotation are considered and discussed. By computing the Nusselt number in various cases, the influence that different parameters have on the flow are revealed.

Numerical Study on the Migration of Two Spheres in Upward Pipe Flow

2018 ◽  
Author(s):  
Lei Liu ◽  
Haining Lu ◽  
Jianmin Yang ◽  
Xinliang Tian ◽  
Tao Peng ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Poiseuille Flow ◽  
Pipe Flow ◽  
Deep Sea ◽  
Numerical Study ◽  
Critical Value ◽  
Dynamic Responses ◽  
Phase Flow ◽  
Two Phase ◽  
Offshore Engineering

Migration of particles in pipe flow is commonly seen in offshore engineering, such as vertical transport of ores in deep sea mining. As the basis of the investigation on fluid-particle two-phase flow, the interaction of two spheres in upward pipe flow is studied by direct numerical simulations in this paper. The pipe flow is set as Poiseuille flow; the Reynolds number is no more than 1250. The dynamic responses of the spheres and the flow pattern are analyzed at different flow velocity. When compared to the sedimentation of two spheres in quiescent flow, the trailing sphere in Poiseuille flow will never surpass the leading one in Poiseuille flow. As the flow velocity increases in the pipe, the spheres are easier to separate after collision. When the flow velocity exceeds a critical value, the spheres will never collide.

scholarly journals Slug genesis in cylindrical pipe flow

2010 ◽  
Vol 663 ◽  
pp. 180-208 ◽  
Author(s):  
Y. DUGUET ◽  
A. P. WILLIS ◽  
R. R. KERSWELL
Keyword(s):  
Phase Space ◽  
Vortex Shedding ◽  
Coherent Structures ◽  
Pipe Flow ◽  
Edge State ◽  
Shear Layers ◽  
Finite Amplitude ◽  
Spatial Expansion ◽  
Cylindrical Pipe ◽  
Low Dimensional

Transition to uniform turbulence in cylindrical pipe flow occurs experimentally via the spatial expansion of isolated coherent structures called ‘slugs’, triggered by localized finite-amplitude disturbances. We study this process numerically by examining the preferred route in phase space through which a critical disturbance initiates a ‘slug’. This entails first identifying the relative attractor – ‘edge state’ – on the laminar–turbulent boundary in a long pipe and then studying the dynamics along its low-dimensional unstable manifold, leading to the turbulent state. Even though the fully turbulent state delocalizes at Re ≈ 2300, the edge state is found to be localized over the range Re = 2000–6000, and progressively reduces in both energy and spatial extent as Re is increased. A key process in the genesis of a slug is found to be vortex shedding via a Kelvin–Helmholtz mechanism from wall-attached shear layers quickly formed at the edge state's upstream boundary. Whether these shedded vortices travel on average faster or slower downstream than the developing turbulence determines whether a puff or a slug (respectively) is formed. This observation suggests that slugs are out-of-equilibrium puffs which therefore do not co-exist with stable puffs.

scholarly journals Numerical study of pressure distribution in entrance pipe flow

2009 ◽  
Vol 25 (3) ◽  
pp. 253-267 ◽  
Author(s):  
Hidesada Kanda ◽  
Kenshuu Shimomukai
Keyword(s):  
Pressure Distribution ◽  
Pipe Flow ◽  
Numerical Study

Eigenvalue Sensitivity to Base Flow Variations in Hagen-Poiseuille Flow

2002 ◽  
Author(s):  
Isabella M. Gavarini ◽  
Alessandro Bottaro ◽  
Frans T. M. Nieuwstadt
Keyword(s):  
Poiseuille Flow ◽  
Pipe Flow ◽  
Reynolds Numbers ◽  
Base Flow ◽  
Transient Growth ◽  
Cylindrical Pipe ◽  
Low Reynolds Numbers ◽  
Parabolic Profile ◽  
Eigenvalue Sensitivity ◽  
The Ideal

Transition in a cylindrical pipe flow still eludes thorough understanding. Most recent advances are based on the concept of transient growth of disturbances, but even this scenario is not fully confirmed by DNS and/or experiments. Based on the fact that even the most carefully conducted experiment is biased by uncertainties, we explore the spatial growth of disturbances developing on top of an almost ideal, axially invariant Poiseuille flow. The optimal deviation of the base flow from the ideal parabolic profile is computed by a variational tecnique, and unstable modes, driven by an inviscid mechanism, are found to exist for very small values of the norm of the deviation, at low Reynolds numbers.

A Numerical Study of Pulsed Turbulent Pipe Flow

1985 ◽  
Vol 107 (2) ◽  
pp. 205-211 ◽  
Author(s):  
V. Reddy ◽  
J. B. McLaughlin ◽  
R. J. Nunge
Keyword(s):  
Pressure Gradient ◽  
Production Rate ◽  
Pipe Flow ◽  
Numerical Study ◽  
Phase Relationship ◽  
Turbulent Pipe Flow ◽  
Wall Region ◽  
Pulsation Frequency ◽  
Axial Pressure Gradient ◽  
Turbulence Production

A numerical study of fully developed turbulent pipe flow due to a sinusoidally varying (with respect to time) axial pressure gradient was carried out using a nonlinear three-dimensional model. Pseudospectral methods were used to solve the model equations. The pulsation frequency was characteristic of the wall region eddies in steady turbulent flow. Attention was focused on the viscous wall region, and it was found that the mean profiles of axial velocity, fluctuation intensities, and turbulence production rate were essentially the same as in steady flow. The fluctuation intensities and the turbulence production rate showed a definite phase relationship to the pressure gradient. The turbulence production rate was the largest at the time in the pulsation cycle at which the largest adverse pressure gradient existed.

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