A numerical study of tidal run up and inundation impact using logical tool-less than equal

Abstract An experimental study and theoretical study is carried out to understand the vibration signature of a propeller shaft. A test rig consists of a rotor shaft and three-disc supported on hydrodynamic bearing was analyzed. Presence of hydrodynamic bearing makes the systems natural frequency speed dependent. A theoretical model of the rotor disc system was developed using FEM. The rotor was formulated on Euler–Bernoulli beam theory. Proportional damping was assumed for the shaft. The stiffness and damping coefficients of the bearing are calculated by short bearing assumption. A Campbell diagram was plotted to observe the variation in natural frequencies with rotational speed. There was an indication of mode approaching each other with a speed which could result in the self-excited phenomena such as “Oil whip”. The hydrodynamic forces in the fluid film produce Oil whip. The presence of Oil whip was ascertained by carrying out the experimental study. The time-frequency plot during the run-up indicated the presence of a whip. The study indicated the influence of modes on the whip phenomena. This can be used in forming guidelines for the safe operating regime for the propeller shaft.

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Numerical Study of Air Gap Response and Wave Impact Load on a Moored Semi-Submersible Platform in Predetermined Irregular Wave Train

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6 ◽

10.1115/omae2010-20260 ◽

2010 ◽

Author(s):

Xiufeng Liang ◽

Jianmin Yang ◽

Longfei Xiao ◽

Xin Li ◽

Jun Li

Keyword(s):

Impact Load ◽

Numerical Study ◽

Wave Train ◽

Air Gap ◽

Navier Stokes ◽

Design Stage ◽

Wave Impact ◽

Irregular Wave ◽

Run Up ◽

Steep Waves

The importance of understanding air gap response and potential deck impact is well-known in the design stage of semi-submersible platform. The highly non-linear nature of wave elevation around large structures in steep waves makes it difficult to accurately predict wave field under the deck and wave run up along the columns. Present engineering tools for the prediction of air gap response generally based on simplified models. Even the models accounting for nonlinear wave diffraction is not free of uncertainties. A method adopted here couples a Navier-Stokes solver, VOF technique capturing violent free surface and DNV/Seasam predicting motions of moored semi-submersible platform. Air gap response at different locations of the hull was evaluated in predetermined irregular wave train. Wave run up was also measured by wave probes near the columns. Load cells were mounted under the deck of the platform to trace potential deck impact. The predetermined irregular wave train was simulated in a numerical wave tank and verified against physical tank results. Analysis of the air gap response, wave run up and impact loads on the semi-submersible platform were conducted.

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Numerical Study of Run-up Oscillations over Fringing Reefs

Journal of Coastal Research ◽

10.2112/jcoastres-d-17-00057.1 ◽

2018 ◽

Vol 345 ◽

pp. 1065-1079 ◽

Cited By ~ 2

Author(s):

D.S. Peláez-Zapata ◽

Rubén D. Montoya ◽

Andrés F. Osorio

Keyword(s):

Numerical Study ◽

Fringing Reefs ◽

Run Up

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Numerical study of periodic long wave run-up on a rigid vegetation sloping beach

Coastal Engineering ◽

10.1016/j.coastaleng.2016.12.004 ◽

2017 ◽

Vol 121 ◽

pp. 158-166 ◽

Cited By ~ 15

Author(s):

Jun Tang ◽

Yongming Shen ◽

Derek M. Causon ◽

Ling Qian ◽

Clive G. Mingham

Keyword(s):

Numerical Study ◽

Rigid Vegetation ◽

Long Wave ◽

Run Up ◽

Sloping Beach

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An analytical and numerical study of long wave run-up in U-shaped and V-shaped bays

Applied Mathematics and Computation ◽

10.1016/j.amc.2016.01.005 ◽

2016 ◽

Vol 279 ◽

pp. 187-197 ◽

Cited By ~ 4

Author(s):

V.V. Garayshin ◽

M.W. Harris ◽

D.J. Nicolsky ◽

E.N. Pelinovsky ◽

A.V. Rybkin

Keyword(s):

Numerical Study ◽

Long Wave ◽

Run Up

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Numerical study of cascading dam-break characteristics using SWEs and RANS

Water Science & Technology Water Supply ◽

10.2166/ws.2019.168 ◽

2019 ◽

Vol 20 (1) ◽

pp. 348-360 ◽

Cited By ~ 2

Author(s):

Shubing Dai ◽

Yong He ◽

Jijian Yang ◽

Yulei Ma ◽

Sheng Jin ◽

...

Keyword(s):

Stokes Equations ◽

Initial Conditions ◽

Numerical Study ◽

Air Entrainment ◽

Dam Break ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Depth Ratio ◽

Surface Profiles ◽

Run Up

Abstract This paper investigates the cascading dam-break flood propagation on the downstream sloping channel and reservoir using the shallow water equations (SWEs) and the Reynolds-average Navier-Stokes equations (RANS). The calculated surface profiles, stage hydrographs and maximum run-up heights for 24 sets of initial conditions are elaborately compared with the experimental measurements, which show the SWEs reproduce the wave oscillation evolution and the maximum run-up height inaccurately. The maximum run-up heights calculated by the SWEs are all smaller than those by the RANS and the measured results, the maximum errors are within −10% to −25%, which may predict delay of the downstream dam-break. However, the maximum errors calculated by the RANS are within ±10%. So the RANS predict more accurate results than the SWEs. Additionally, the generation of short waves must be below a certain upstream-to-downstream ‘depth ratio’, roughly the ‘depth ratio’ <2/3 in this study. If the ratio is too high, it is difficult to form a wavy push due to air entrainment and turbulence. The SWEs predict more accurate results for shallow initial depths than deep initial depths. Therefore, the advantage of the RANS can be more obvious for deep initial depths.

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