scholarly journals Storm, rogue wave, or tsunami origin for megaclast deposits in western Ireland and North Island, New Zealand?

2017 ◽  
Vol 114 (50) ◽  
pp. E10639-E10647 ◽  
Author(s):  
John F. Dewey ◽  
Paul D. Ryan
Keyword(s):  
New Zealand ◽  
Numerical Model ◽  
Field Data ◽  
Rogue Wave ◽  
Hydrodynamic Equations ◽  
Ne Atlantic ◽  
Lower Miocene ◽  
Storm Deposit ◽  
Western Ireland

The origins of boulderite deposits are investigated with reference to the present-day foreshore of Annagh Head, NW Ireland, and the Lower Miocene Matheson Formation, New Zealand, to resolve disputes on their origin and to contrast and compare the deposits of tsunamis and storms. Field data indicate that the Matheson Formation, which contains boulders in excess of 140 tonnes, was produced by a 12- to 13-m-high tsunami with a period in the order of 1 h. The origin of the boulders at Annagh Head, which exceed 50 tonnes, is disputed. We combine oceanographic, historical, and field data to argue that this is a cliff-top storm deposit (CTSD). A numerical model for CTSDs is developed which indicates that boulder shape in addition to density and dimensions should be taken into account when applying hydrodynamic equations to such deposits. The model also predicts that the NE Atlantic storms are capable of producing boulderites that, when size alone is considered, cannot be distinguished from tsunamites. We review the characteristics that identify the origins of these two deposits.

Multiphase Transient Slugging Flow in Subsea Oil and Gas Production

2016 ◽  
Author(s):  
Zhenhua Zhang ◽  
Longbin Tao
Keyword(s):  
Data Analysis ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Slug Flow ◽  
Field Data ◽  
Oil And Gas ◽  
Gas Production ◽  
Worst Case ◽  
Oil And Gas Production ◽  
Significant Difference

Slug flow in horizontal pipelines and riser systems in deep sea has been proved as one of the challenging flow assurance issues. Large and fluctuating gas/liquid rates can severely reduce production and, in the worst case, shut down, depressurization or damage topside equipment, such as separator, vessels and compressors. Previous studies are primarily based on experimental investigations of fluid properties with air/water as working media in considerably scaled down model pipes, and the results cannot be simply extrapolated to full scale due to the significant difference in Reynolds number and other fluid conditions. In this paper, the focus is on utilizing practical shape of pipe, working conditions and fluid data for simulation and data analysis. The study aims to investigate the transient multiphase slug flow in subsea oil and gas production based on the field data, using numerical model developed by simulator OLGA and data analysis. As the first step, cases with field data have been modelled using OLGA and validated by comparing with the results obtained using PIPESYS in steady state analysis. Then, a numerical model to predict slugging flow characteristics under transient state in pipeline and riser system was set up using multiphase flow simulator OLGA. One of the highlights of the present study is the new transient model developed by OLGA with an added capacity of newly developed thermal model programmed with MATLAB in order to represent the large variable temperature distribution of the riser in deep water condition. The slug characteristics in pipelines and temperature distribution of riser are analyzed under the different temperature gradients along the water depth. Finally, the depressurization during a shut-down and then restart procedure considering hydrate formation checking is simulated. Furthermore, slug length, pressure drop and liquid hold up in the riser are predicted under the realistic field development scenarios.

scholarly journals ROGUE WAVE ASYMMETRY IN THE DIRECT NUMERICAL SIMULATIONS OF DIRECTIONAL JONSWAP WAVES

2020 ◽  
pp. 48
Author(s):  
Alexey Slunyaev ◽  
Anna Kokorina
Keyword(s):  
Water Wave ◽  
Rogue Wave ◽  
Rogue Waves ◽  
Hydrodynamic Equations ◽  
Laboratory Measurements ◽  
Term Evolution ◽  
Typical Picture ◽  
High Order Spectral Method

The asymmetry between the troughs from the rear and front sides of rogue waves is the particular object of the present study. In our previous simulations of unidirectional waves the typical picture of a rogue waves possesses the trend that most of the rogue waves where characterized by deeper rear troughs. In the present work we broaden the discussion of the rogue wave front-to-crest asymmetry to the directional case. The direct numerical simulation of primitive water equations is an affordable alternative to the in-situ or laboratory measurements, in particularly when the interest is focused on the long-term evolution or on the detailed consideration of the water wave movement in space and time. In this work we simulate irregular surface waves in the hydrodynamic equations using the High-Order Spectral Method, and focus on the so-called rogue waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/plseXdjpE6c

scholarly journals Coastal Boulders on the SE Coasts of Cyprus as Evidence of Palaeo-Tsunami Events

2020 ◽  
Vol 8 (10) ◽  
pp. 812
Author(s):  
Niki Evelpidou ◽  
Christos Zerefos ◽  
Costas Synolakis ◽  
Christos Repapis ◽  
Anna Karkani ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Field Data ◽  
Extreme Event ◽  
High Energy ◽  
Hydrodynamic Equations ◽  
Differential Gps ◽  
Upper Pleistocene ◽  
Three Samples ◽  
Lower Pleistocene ◽  
History Of

Cyprus has a long history of tsunami events, as noted by archaeological and geological records. At Cape Greco (southeastern Cyprus) large boulders have been noted, however, no detailed geomorphological research has taken place so far and the related high energy event was undated until now. Our research aims to record in detail and interpret these large boulders deposits. The boulders, located between ≈3 and 4.5 m a.m.s.l., are fragments of an upper Pleistocene aeolianite, which is overlaying unconformly a lower Pleistocene calcarenite. Dimensions and spatial distribution of 272 small, medium, and large boulders were documented, while their precise distance from the coastline was recorded by field mapping and remote sensing, using Differential GPS (DGPS), drone, and Geographic Information Systems (GIS) technics. Field data were subsequently combined with hydrodynamic equations, in order to determine the extreme event(s) that caused their transport inland, and radiocarbon dating was accomplished on three samples of Vermetus sp. to determine the chronological context. Our findings appear to broadly correlate with the 1303 AD tsunami, which has displaced at least part of the studied boulders, and one other undocumented event at AD 1512-1824. The large number of boulders and sizes in our study area further indicate that their dislocation is most likely owed to multiple events from various sources.

Dynamic uplift in a transpressional regime: numerical model of the subduction area of Fiordland, New Zealand

2003 ◽  
Vol 206 (3-4) ◽  
pp. 349-364 ◽  
Author(s):  
Rocco Malservisi ◽  
Kevin P. Furlong ◽  
Helen Anderson
Keyword(s):  
New Zealand ◽  
Numerical Model

A practical technique for estimating service life of MSW leachate collection systems

2013 ◽  
Vol 50 (2) ◽  
pp. 165-178 ◽  
Author(s):  
R. Kerry Rowe ◽  
Yan Yu
Keyword(s):  
Numerical Model ◽  
Service Life ◽  
Field Data ◽  
Oxygen Demand ◽  
Collection System ◽  
Leachate Collection ◽  
Design Charts ◽  
Leachate Characteristics ◽  
Practical Model ◽  
Measured Field

The leachate characteristics and clogging of the leachate collection system at the Keele Valley Landfill is examined using the numerical model “BioClog”. The calculated effluent leachate concentrations (e.g., the chemical oxygen demand and calcium concentrations) and calculated calcium fraction in the clog material are in encouraging agreement with measured field data. A new practical model is developed and calibrated against the data from the sophisticated numerical model to estimate the service life of leachate collection systems in typical municipal solid waste (MSW) landfills. The procedures for using the new practical model are provided and illustrated by examples. Design charts are presented that may aid the design of leachate collection systems for typical MSW landfills.

scholarly journals FLOW COMPUTATIONS NEARBY A STORM SURGE BARRIER UNDER CONSTRUCTION WITH TWO-DIMENSIONAL NUMERICAL MODELS

1986 ◽  
Vol 1 (20) ◽  
pp. 143
Author(s):  
H.E. Klatter ◽  
J.M.C. Dijkzeul ◽  
G. Hartsuiker ◽  
L. Bijlsma
Keyword(s):  
Numerical Model ◽  
Storm Surge ◽  
Field Data ◽  
Numerical Models ◽  
Flow Patterns ◽  
Scale Model ◽  
Energy Losses ◽  
Local Energy ◽  
Two Dimensional ◽  
Physical Scale

This paper discusses the application of two-dimensional tidal models to the hydraulic research for the storm surge barrier in the Eastern Scheldt in the Netherlands. At the site of the barrier local energy losses dominate the flow. Three methods are discussed for dealing with these energy losses in a numerical model based on the long wave equations. The construction of the storm surge barrier provided extensive field data for various phases of the construction of the barrier and these field data are used as a test case for the computation at methods developed. One method is preferred since it gives good agreement between computations and field data. The two-dimensional flow patterns, the discharge and the head-difference agree well,, The results of scale model tests were also available for comparison. This comparison demonstrated that depth-averaged velocities, computed by a two-dimensional numerical model, are as accurate as values obtained from a large physical scale model. Even compicated flow patterns with local energy losses and sharp velocity gradients compared well.

scholarly journals GENERAL MODEL FOR ESTIMATION OF LONGSHORE TRANSPORT AT SHINGLE/MIXED BEACHES

2017 ◽  
pp. 26
Author(s):  
Giuseppe Roberto Tomasicchio ◽  
Felice D'Alessandro ◽  
Giuseppe Barbaro ◽  
Francesco Ciardulli ◽  
Antonio Francone ◽  
...  
Keyword(s):  
New Zealand ◽  
Field Experiment ◽  
General Model ◽  
Field Data ◽  
East Coast ◽  
Data Sets ◽  
Predictive Capability ◽  
Longshore Transport ◽  
Sand And Gravel ◽  
Gravel Beach

In the present study, the accuracy of the GLT model (Tomasicchio et al., 2013) has been verified for the estimation of the Longshore Transport (LT) at shingle/mixed beaches. In order to verify the suitability of the GLT model in determining LT estimates at shingle beaches, without any further calibration, the comparison between the LT predictions and observations from two field data sets (Chadwick, 1989; Nicholls and Wright, 1991) has been considered. The comparison showed that the GLT predicted LT rates within a factor of 2 of the observed values. The predictive capability of the GLT has been also verified against an alternative general formula for the LT estimation at shingle beaches (Van Rijn, 2014). In addition, the suitability of the GLT model, even for the mixed beach case, has been assessed by means of the comparison between the LT prediction and the observation from a field experiment on a mixed sand and gravel beach at Hawke’s Bay, on the east coast of New Zealand (Komar, 2010).

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