scispace - formally typeset
Search or ask a question
Topic

Pipe flow

About: Pipe flow is a research topic. Over the lifetime, 13826 publications have been published within this topic receiving 351605 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a capsule is modeled as a liquid drop surrounded by an elastic membrane which follows neo-Hookean law, and the capsule deformation is modelled as a quasi-steady process irrespective of capillary number, viscosity ratio, capsule-to-channel size ratio, and lateral location.

178 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental study was carried out to investigate the transition from laminar to turbulent flow in helically coiled pipes, and the interaction between turbulence emergence and coil curvature has been analyzed from direct observation of the experimental friction factor profiles.

178 citations

Journal ArticleDOI
TL;DR: In this paper, the authors report on (two-component) LDV experiments in a fully developed tur- bulent pipe flow with a drag-reducing polymer (partially hydrolyzed polyacrylamide) dissolved in water.
Abstract: In this paper we report on (two-component) LDV experiments in a fully developed tur- bulent pipe flow with a drag-reducing polymer (partially hydrolyzed polyacrylamide) dissolved in water. The Reynolds number based on the mean velocity, the pipe diameter and the local viscosity at the wall is approximately 10000. We have used polymer solutions with three different concentrations which have been chosen such that maximum drag reduction occurs. The amount of drag reduction found is 60-70%. Our experimental results are compared with results obtained with water and with a very dilute solution which exhibits only a small amount of drag reduction. We have focused on the observation of turbulence statistics (mean velocities and turbulence intensities) and on the various contributions to the total shear stress. The latter consists of a turbulent, a solvent (viscous) and a polymeric part. The polymers are found to contribute significantly to the total stress. With respect to the mean velocity profile we find a thickening of the buffer layer and an increase in the slope of the logarithmic profile. With respect to the turbulence statistics we find for the streamwise velocity fluctuations an increase of the root mean square at low polymer concentration but a return to values comparable to those for water at higher concentrations. The root mean square of the normal velocity fluctuations shows a strong decrease. Also the Reynolds (turbulent) shear stress and the correlation coefficient between the streamwise and the normal components are drastically reduced over the entire pipe diameter. In all cases the Reynolds stress stays definitely non-zero at maximum drag reduction. The consequence of the drop of the Reynolds stress is a large polymer stress, which can be 60% of the total stress. The kinetic-energy balance of the mean flow shows a large transfer of energy directly to the polymers instead of the route by turbulence. The kinetic energy of the turbulence suggests a possibly negative polymeric dissipation of turbulent energy.

177 citations

Journal ArticleDOI
TL;DR: In this paper, a general class of viscoelastic model is used to investigate numerically the pattern and strength of the secondary flows in rectangular pipes as well as the influence of material parameters on them.
Abstract: In this paper, a general class of viscoelastic model is used to investigate numerically the pattern and strength of the secondary flows in rectangular pipes as well as the influence of material parameters on them. To solve the coupled governing equation system, an implicit finite volume method based on the SIMPLEST algorithm, which is applicable for both time-dependent and steady-state flow computations, has been developed and extended for viscoelastic flow computations by applying the decoupled techniques. The main feature of the method is to split the solution process into a series of steps in which the continuity of the flow field is enforced by solving a Poisson's equation for the pressure, and at the end of the steps, both the pressure and velocity fields are made to satisfy one and the same momentum equation. For viscoelastic flow computations, artificial diffusion terms are introduced on both sides of the discretized constitutive equations to improve numerical stability. It is found that there are in total two vortices in each quadrant of the pipe at different aspect ratios (from 1 to 16), and at each ratio the pattern of secondary flows takes the same form for different material parameters, but their strength is very sensitive to the viscoelastic material parameters. Numerical results indicate that the presence of secondary flow strongly depends on the primary flow rate and the elasticity of the fluid, namely, the first and the second normal stress differences as well as their functional departure from the constant multiple viscosity.

177 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the trajectory and entrainment characteristics of a round jet in crossflow and showed that the entrainments of crossflow fluid is the primary mechanism by which the jet trajectory is determined.
Abstract: This paper examines the trajectory and entrainment characteristics of a round jet in crossflow. A series of large eddy simulations was performed at Reynolds numbers of 1050 and 2100 and at jet to crossflow velocity ratios of 2.0 and 3.3. Trajectories, which are defined based on the mean streamlines on the centerplane, all collapse to a single curve far from the jet exit, and this curve can be represented with a power law fit. Within this power law region, entrainment of crossflow fluid is shown to be the primary mechanism by which the jet trajectory is determined. Upstream of the power law region, near the jet exit, jet trajectory varies from changes in pressure drag and from differences in the turbulence intensities in the incoming pipe flow.

177 citations


Network Information
Related Topics (5)
Reynolds number
68.4K papers, 1.6M citations
95% related
Laminar flow
56K papers, 1.2M citations
92% related
Fluid dynamics
47.9K papers, 1M citations
90% related
Turbulence
112.1K papers, 2.7M citations
89% related
Heat transfer
181.7K papers, 2.9M citations
89% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202335
202275
2021170
2020177
2019273
2018281