scholarly journals Time-prediction of an onset of failure in full-scale model slope due to multi-step excavations based on Fukuzono formula

2018 ◽  
Vol 13 (1) ◽  
pp. 13-25
Author(s):  
Katsuo SASAHARA ◽  
Naoki IWATA ◽  
Naotaka KIKKAWA ◽  
Nobutaka HIRAOKA ◽  
Kazuya ITOH
Keyword(s):  
Full Scale ◽  
Scale Model ◽  
Time Prediction ◽  
Model Slope

scholarly journals Evaluation of an instability for a full-scale model slope under multi-step excavation based on the monitoring of 2-dimensional displacements

2019 ◽  
Vol 14 (4) ◽  
pp. 363-375
Author(s):  
Katsuo SASAHARA ◽  
Nobutaka HIRAOKA ◽  
Naotaka KIKKAWA ◽  
Kazuya ITOH
Keyword(s):  
Full Scale ◽  
Scale Model ◽  
Model Slope

Effect of mesh on CFD aerodynamic performances of a container ship

2020 ◽  
Vol 20 (3) ◽  
pp. 343-353
Author(s):  
Ngo Van He ◽  
Le Thi Thai
Keyword(s):  
Water Surface ◽  
Reference Model ◽  
Full Scale ◽  
Scale Model ◽  
Container Ship ◽  
Ansys Fluent ◽  
Remarkable Effect ◽  
Aerodynamic Performances ◽  
Mesh Convergence

In this paper, a commercial CFD code, ANSYS-Fluent has been used to investigate the effect of mesh number generated in the computed domain on the CFD aerodynamic performances of a container ship. A full-scale model of the 1200TEU container ship has been chosen as a reference model in the computation. Five different mesh numbers for the same dimension domain have been used and the CFD aerodynamic performances of the above water surface hull of the ship have been shown. The obtained CFD results show a remarkable effect of mesh number on aerodynamic performances of the ship and the mesh convergence has been found. The study is an evidence to prove that the mesh number has affected the CFD results in general and the accuracy of the CFD aerodynamic performances in particular.

Benchmarking of Truss Spar Vortex Induced Motions Derived From CFD With Experiments

2005 ◽  
Author(s):  
John Halkyard ◽  
Senu Sirnivas ◽  
Samuel Holmes ◽  
Yiannis Constantinides ◽  
Owen H. Oakley ◽  
...  
Keyword(s):  
Scale Up ◽  
Vertical Cylinder ◽  
Reynolds Numbers ◽  
Full Scale ◽  
Scale Model ◽  
Current Direction ◽  
Test Results ◽  
Helical Strakes ◽  
Truss Spar ◽  
Scale Data

Floating spar platforms are widely used in the Gulf of Mexico for oil production. The spar is a bluff, vertical cylinder which is subject to Vortex Induced Motions (VIM) when current velocities exceed a few knots. All spars to date have been constructed with helical strakes to mitigate VIM in order to reduce the loads on the risers and moorings. Model tests have indicated that the effectiveness of these strakes is influenced greatly by details of their design, by appurtenances placed on the outside of the hull and by current direction. At this time there is limited full scale data to validate the model test results and little understanding of the mechanisms at work in strake performance. The authors have been investigating the use of CFD as a means for predicting full scale VIM performance and for facilitating the design of spars for reduced VIM. This paper reports on the results of a study to benchmark the CFD results for a truss spar with a set of model experiments carried out in a towing tank. The focus is on the effect of current direction, reduced velocity and strake pitch on the VIM response. The tests were carried out on a 1:40 scale model of an actual truss spar design, and all computations were carried out at model scale. Future study will consider the effect of external appurtenances on the hull and scale-up to full scale Reynolds’ numbers on the results.

Drilling Riser VIV Tests With Prototype Reynolds Numbers

2013 ◽  
Author(s):  
Halvor Lie ◽  
Henning Braaten ◽  
Jamison Szwalek ◽  
Massimiliano Russo ◽  
Rolf Baarholm
Keyword(s):  
Cross Flow ◽  
Effect Study ◽  
Full Scale ◽  
Scale Model ◽  
Small Scale ◽  
Scaling Effects ◽  
Research Activity ◽  
Forced Motion ◽  
Auxiliary Lines ◽  
Viv Suppression

For deep-water riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale riser model. The rigid riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction. The paper reports results from a drilling riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable riser systems with auxiliary lines by adding riser fins. These fins are normally used as devices for protection of the auxiliary lines. The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published. A bare riser model was used in a Reynolds number (Rn) scaling effect study. The riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant. The elastically mounted riser was also towed with various drilling riser configurations in order to study VIV/galloping responses. One configuration included a slick joint riser model with 6 kill & choke lines; another has added riser fins too. The riser model is based on a specific drilling riser and the kill and choke lines have various diameters and have a non-symmetrical layout. The various riser configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later. Scaling effects appear to be a significant uncertainty and further research on the subject is recommended. The slick joint drilling riser configuration generally increased the displacements compared to displacements of the bare riser model. The drilling riser configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare riser model. For both riser systems, tests showed that the response is sensitive to the heading of the current.

Full scale model tests on slab track constructed on embankment

2012 ◽  
pp. 547-553 ◽  
Author(s):  
Jiang Hongguang ◽  
Bian Xuecheng ◽  
Chen Yunmin ◽  
Jiang Jianqun
Keyword(s):  
Model Tests ◽  
Full Scale ◽  
Scale Model ◽  
Slab Track

scholarly journals MODELING OF DISTURBANCES IN STUDY OF CONTROL SYSTEMS

2020 ◽  
Vol 2020 (4) ◽  
pp. 70-79
Author(s):  
Mikhail Vasilevich Lyakhovets ◽  
Georgiy Valentinovich Makarov ◽  
Alexandr Sergeevich Salamatin
Keyword(s):  
Control Systems ◽  
Generating Functions ◽  
Special Functions ◽  
Computer Training ◽  
Full Scale ◽  
Analytical Models ◽  
Scale Model ◽  
Data Series ◽  
Dynamic Databases ◽  
Natural Data

The article is devoted to questions of synthesis of full-scale - model realizations of data series on the basis of natural data for modeling of controllable and uncontrollable influences at research of operating and projected control systems, and also in training systems of computer training. The possibility of formation of model effects on the basis of joint use of multivariate dynamic databases and natural data simulator is shown. Dynamic databases store information that characterizes the typical representative situations of systems in the form of special functions - generating functions. Multiple variability of dynamic databases is determined by the type of the selected generating function, the methods of obtaining parameters (coefficients) of this function, as well as the selected accuracy of approximation. The situation models recovered by generating functions are used as basic components (trends) in the formation of the resulting full-scale - model implementations and are input into the natural data simulator. The data simulator allows for each variant of initial natural data to form an implementation of the perturbation signal with given statistical properties on a given simulation interval limited by the initial natural implementation. This is achieved with the help of a two-circuit structure, where the first circuit is responsible for evaluation and cor-rection of initial properties of the natural signal, and the second - for iterative correction of deviations of properties of the final implementation from the specified ones. The resulting realizations reflect the properties of their full-scale components, which are difficult to describe by analytical models, and are supplemented by model values, allowing in increments to correct the properties to the specified ones. The given approach allows to form set of variants of course of processes on the basis of one situation with different set degree of uncertainty and conditions of functioning.

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