Numerical Modeling of Turbulent Wall-Bounded Oscillatory Flow and Its Effect on Small-Diameter Pipelines

2021 ◽  
Author(s):  
Hongyi Jiang ◽  
Liang Cheng
Keyword(s):  
Numerical Modeling ◽  
Oscillatory Flow ◽  
Small Diameter ◽  
Turbulent Wall

Numerical Modeling of Turbulent Wall-Bounded Oscillatory Flow and its Effect on Small-Diameter Pipelines

2020 ◽  
Author(s):  
Hongyi Jiang ◽  
Liang Cheng
Keyword(s):  
Boundary Layer ◽  
Oscillatory Flow ◽  
Small Diameter ◽  
Viscous Sublayer ◽  
Theoretical Estimation ◽  
Wall Boundary Condition ◽  
Mesh Resolution ◽  
Turbulent Wall ◽  
Wave Induced ◽  
Wave Boundary

Abstract This study investigates the effect of wave-induced boundary layer on the on-bottom stability of small-diameter pipelines laid on the seabed. An ω-based wall boundary condition is adopted, owing to its high mesh resolution down to the viscous sublayer to resolve the flow around the pipeline. By taking into account the wave boundary layer, the present numerical simulations predict required specific gravity for small-diameter pipelines close to the theoretical estimation by Cheng et al. (2016) and, as expected, much smaller than those recommended by DNV-RP-F109.

Oscillatory flow in curved pipes. Part 2. The fully developed case

1980 ◽  
Vol 98 (2) ◽  
pp. 397-416 ◽  
Author(s):  
T. Mullin ◽  
C. A. Greated
Keyword(s):  
Oscillatory Flow ◽  
Stokes Equations ◽  
Laser Doppler Anemometry ◽  
Small Diameter ◽  
Integral Transforms ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Closed Form Solutions ◽  
Curved Pipes ◽  
Glass Tubes

A theoretical and experimental investigation of oscillatory flow in curved pipes is presented. The equations for fully developed laminar flow are found to depend on an amplitude parameterGand a frequency parameter α. Initially the Navier–Stokes equations are expanded in terms ofGand the resulting linearized equations are solved numerically using finite Hankel integral transforms. A further expansion is used for the case α → 0 and closed-form solutions are presented.Laser-Doppler anemometry has been used to obtain velocity information in oscillatory air flow in small-diameter curved glass tubes. Using this technique, low-Reynolds-number experiments were carried out and comparison between theory and experiments is presented.For α [les ] 1 the velocity distributions found are essentially those for steady flow, while for α [ges ] 11·0 the results are not at variance with earlier work. It is for the transition stage between these two regimes that unexpected behaviour is recorded, but a satisfactory explanation is found in terms of general trends within the flow.

Performance Monitoring and Modeling of Small Diameter MDPE Natural Gas Pipelines Subject to Ground Movement

2014 ◽  
Author(s):  
Aaron Dinovitzer ◽  
Abdelfettah Fredj ◽  
Lalinda Weerasekara ◽  
Mujib Rahman ◽  
Dharma Wijewickreme
Keyword(s):  
Numerical Modeling ◽  
Natural Gas ◽  
Distribution Systems ◽  
Small Diameter ◽  
Material Behavior ◽  
Ground Movement ◽  
Pipe System ◽  
Plastic Pipes ◽  
Effective Manner ◽  
Soil Pipe

Considering the need to undertake pipeline replacement in a cost-effective manner while ensuring the public safety interest, evaluating the performance of pipelines subject to soil loading from landslides is a key concern in some of the natural gas distribution systems operated by FortisBC Inc. As it is typically uneconomical and impractical to relieve stresses in distribution pipe systems by excavating or instrumenting the pipelines to measure the highly localized strains, undertaking numerical and/or analytical modeling combined with experimentation is a key aspect in attempting to relate the measured ground movement to performance of pipe. For this purpose, capturing the fundamental soil-pipe interaction in small-diameter extensible plastic pipes and undertaking field monitoring to validate the numerical model are critically important. With this background, this paper presents field measurement and numerical modeling undertaken to model the performance of 115 mm diameter medium density polyethylene (MDPE) pipes buried in West Quesnel, BC, Canada. Using field survey data, the active landslides occurring perpendicular to the pipe axis at these two sites have been periodically characterized since 2000/2001. Materials removed from the pipe system were tested to characterize the pipeline material behavior and limit strains. The data derived from these tests along with a range of soil behaviors are used to support pipe-soil interaction numerical simulation and thus characterize the strains accumulated in the pipeline in service. This paper discusses the limitations, challenges and recommendations for numerical modeling of soil-pipe interaction in small-diameter plastic pipes.

A Replica Technique for the Inside Surfaces of Small Diameter Pipes and Tubes

1967 ◽  
Vol 25 ◽  
pp. 352-353
Author(s):  
T. G. Gregory
Keyword(s):  
Polyvinyl Chloride ◽  
Small Diameter ◽  
Replica Technique ◽  
Tube Size ◽  
Inside Diameter ◽  
Complete Inspection ◽  
Operating Limits

A nondestructive replica technique permitting complete inspection of bore surfaces having an inside diameter from 0.050 inch to 0.500 inch is described. Replicas are thermally formed on the outside surface of plastic tubing inflated in the bore of the sample being studied. This technique provides a new medium for inspection of bores that are too small or otherwise beyond the operating limits of conventional inspection methods.Bore replicas may be prepared by sliding a length of plastic tubing completely through the bore to be studied as shown in Figure 1. Polyvinyl chloride tubing suitable for this replica process is commercially available in sizes from 0.037- to 0.500-inch diameter. A tube size slightly smaller than the bore to be replicated should be used to facilitate insertion of the plastic replica blank into the bore.

Structural Organization and Distribution of Fiber Types in Extraocular Muscles of Cats

1972 ◽  
Vol 30 ◽  
pp. 34-35
Author(s):  
Asish C. Nag ◽  
Lee D. Peachey
Keyword(s):  
Fiber Type ◽  
Light And Electron Microscopy ◽  
Small Diameter ◽  
Extraocular Muscles ◽  
Fiber Types ◽  
Distinctive Features ◽  
Superior Rectus ◽  
Adult Cats ◽  
Different Diameters ◽  
Orbital Region

Cat extraocular muscles consist of two regions: orbital, and global. The orbital region contains predominantly small diameter fibers, while the global region contains a variety of fibers of different diameters. The differences in ultrastructural features among these muscle fibers indicate that the extraocular muscles of cats contain at least five structurally distinguishable types of fibers.Superior rectus muscles were studied by light and electron microscopy, mapping the distribution of each fiber type with its distinctive features. A mixture of 4% paraformaldehyde and 4% glutaraldehyde was perfused through the carotid arteries of anesthetized adult cats and applied locally to exposed superior rectus muscles during the perfusion.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

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