Boundary Layer Solution for the Turbulent Swirling Decay Flow Through a Fixed Pipe: SBR at the Inlet

2003 ◽  
Author(s):  
A. F. Najafi ◽  
M. H. Saidi ◽  
M. S. Sadeghipour ◽  
M. Souhar
Keyword(s):  
Boundary Layer ◽  
Pipe Flow ◽  
Reasonable Agreement ◽  
Cfd Analysis ◽  
Governing Equations ◽  
Solid Body Rotation ◽  
Swirl Intensity ◽  
Fluent Software ◽  
Flow Through ◽  
Layer Solution

In this study the developing turbulent swirling pipe flow is investigated both numerically and analytically. Governing equations are derived accompanying the boundary layer assumptions. Uniform and solid body rotation (SBR) distributions are taken into account for the axial and tangential velocities at the inlet of the pipe, respectively. Beyond the boundary layers, the flow pattern is considered to be the potential flow. Making use of the fourth-order Runge-Kutta scheme, the numerical solution of the differential equations is obtained. Further more, by simplifying the governing equations for large Rossby number, the analytical solution is performed. The results of numerical and analytical swirl intensity have been compared showing reasonable agreement. As an alternative solution, a CFD analysis has been done as well, having applied FLUENT software to support the ability of our methodology.

Bifurcation analysis of two-dimensional laminar flow through sudden expansion channel

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Laminar Flow ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Two Dimensional ◽  
Governing Equations ◽  
Bifurcation Phenomena ◽  
Different Types ◽  
Fluent Software ◽  
Flow Through ◽  
Volume Method

In this work, bifurcation characteristics of unsteady, viscous, Newtonian laminar flow in two-dimensional sudden expansion and sudden contraction-expansion channels have been studied for different values of expansion ratio. The governing equations have been solved using finite volume method and FLUENT software has been employed to visualize the simulation results. Three different mesh studies have been performed to calculate critical Reynolds number (Recr) for different types of bifurcation phenomena. It is found that Recr decreases with the increase in expansion ratio (ER).

scholarly journals Two stage ejector as a pre-stage of the water ring vacuum pump

2019 ◽  
Vol 20 (7) ◽  
pp. 703
Author(s):  
Róbert Olšiak ◽  
Marek Mlkvik ◽  
František Ridzoň ◽  
Pavol Slovák
Keyword(s):  
Experimental Studies ◽  
Vacuum Pump ◽  
3D Printer ◽  
Cfd Analysis ◽  
Suction Pressure ◽  
Governing Equations ◽  
Flow Through ◽  
Definition Of ◽  
Water Ring ◽  
Liquid Ring

A supersonic gas ejector in conjunction with a liquid ring vacuum pump is used for creating and maintaining a vacuum in a chamber for technological purposes. In this paper, the authors submit an overview of the problematics of suction pressure reduction with a supersonic gas ejector used as a pre-stage of a liquid ring vacuum pump. This system has also the function of a cavitation protection due to the higher pressure present at the suction throat of the vacuum pump. A part of this paper is devoted to the governing equations used at the definition of the flow through an ejector. The CFD analysis of the problem was implemented with the package Fluent in 2 dimensions using the axisymmetric approach. The parts of the physical model were printed on a STRATASYS 3D printer, or were cast from technical resin. The experimental studies are then carried out in our own laboratory for validation purposes.

Further Experiments With Suction at a Sudden Enlargement in a Pipe

1970 ◽  
Vol 92 (3) ◽  
pp. 437-447 ◽  
Author(s):  
Gunnar Heskestad
Keyword(s):  
Boundary Layer ◽  
Pipe Flow ◽  
Expansion Ratio ◽  
Turbulent Pipe Flow ◽  
Thin Boundary Layer ◽  
Inlet Flow ◽  
Upper Limit ◽  
Sudden Enlargement ◽  
Flow Through ◽  
And Performance

Previously reported experiments on incompressible flow through a step expansion in a pipe, as influenced by suction at the smaller diameter of the step, have been extended to examine effects of inlet flow on suction requirements and performance of the device as a (short) diffuser. Here the performance for a fully developed turbulent pipe flow is considered and compared to previous results for an inlet flow with thin boundary layer. Whenever overall diffuser length is restricted to values less than some upper limit for a given expansion ratio, then for either inlet flow condition, the present device is shown to produce higher pressure recoveries (adjusted for suction power) than conical diffusers.

Convective diffusion to a slowly rotating spherical electrode; Basic model for Re → O, Pe → ∞

1983 ◽  
Vol 48 (6) ◽  
pp. 1571-1578 ◽  
Author(s):  
Ondřej Wein
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Peclet Number ◽  
Convective Diffusion ◽  
Creeping Flow ◽  
Péclet Number ◽  
Spherical Electrode ◽  
Basic Model ◽  
Boundary Layer Solution ◽  
Layer Solution

Theory has been formulated of a convective rotating spherical electrode in the creeping flow regime (Re → 0). The currently available boundary layer solution for Pe → ∞ has been confronted with an improved similarity description applicable in the whole range of the Peclet number.

scholarly journals Mathematical study on two-fluid model for flow of K–L fluid in a stenosed artery with porous wall

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
R. Ponalagusamy ◽  
Ramakrishna Manchi
Keyword(s):  
Theoretical Study ◽  
Fluid Model ◽  
Porous Wall ◽  
Governing Equations ◽  
Rate Of Increase ◽  
Special Cases ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid Model ◽  
Two Fluid

AbstractThe present communication presents a theoretical study of blood flow through a stenotic artery with a porous wall comprising Brinkman and Darcy layers. The governing equations describing the flow subjected to the boundary conditions have been solved analytically under the low Reynolds number and mild stenosis assumptions. Some special cases of the problem are also presented mathematically. The significant effects of the rheology of blood and porous wall of the artery on physiological flow quantities have been investigated. The results reveal that the wall shear stress at the stenotic throat increases dramatically for the thinner porous wall (i.e. smaller values of the Brinkman and Darcy regions) and the rate of increase is found to be 18.46% while it decreases for the thicker porous wall (i.e. higher values of the Brinkman and Darcy regions) and the rate of decrease is found to be 10.21%. Further, the streamline pattern in the stenotic region has been plotted and discussed.

Analysis of an Airfoil Using a Transition and Turbulence Model

2016 ◽  
Vol 819 ◽  
pp. 356-360
Author(s):  
Mazharul Islam ◽  
Jiří Fürst ◽  
David Wood ◽  
Farid Nasir Ani
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Turbulence Model ◽  
Original Version ◽  
Transitional Region ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

In order to evaluate the performance of airfoils with computational fluid dynamics (CFD) tools, modelling of transitional region in the boundary layer is very critical. Currently, there are several classes of transition-based turbulence model which are based on different methods. Among these, the k-kL- ω, which is a three equation turbulence model, is one of the prominent ones which is based on the concept of laminar kinetic energy. This model is phenomenological and has several advantageous features. Over the years, different researchers have attempted to modify the original version which was proposed by Walter and Cokljat in 2008 to enrich the modelling capability. In this article, a modified form of k-kL-ω transitional turbulence model has been used with the help of OpenFOAM for an investigative CFD analysis of a NACA 4-digit airfoil at range of angles of attack.

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