wave model
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Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 469
Author(s):  
Theofanis Karambas ◽  
Eva Loukogeorgaki

In the present work, a Boussinesq-type numerical model is developed for the simulation of nonlinear wave-heaving cylinder interaction. The wave model is able to describe the propagation of fully dispersive and weakly nonlinear waves over any finite water depth. The wave-cylinder interaction is taken into account by solving simultaneously an elliptic equation that determines the pressure exerted by the fluid on the floating body. The heave motion for the partially immersed floating cylinder under the action of waves is obtained by solving numerically the body’s equation of motion in the z direction based on Newton’s law. The developed model is applied for the case of a fixed and a free-floating circular cylinder under the action of regular waves, as well as for a free-floating cylinder undergoing a forced motion in heave. Results (heave and surge exciting forces, heave motions, and wave elevation) are compared with those obtained using a frequency domain numerical model, which is based on the boundary integral equation method.


MAUSAM ◽  
2021 ◽  
Vol 66 (3) ◽  
pp. 617-624
Author(s):  
SUBEKTI MUJIASIH ◽  
DANANGEKO NURYANTO

2021 ◽  
Author(s):  
Paul C. Rivera

Manila Bay is a shallow coastal water encompassing the urban areas of Metro Manila and variouscities of sub-urban provinces in the Philippines. It is a relatively shallow semi-enclosed basinwith an average depth of 20 m whose coastal areas are crowded with residential, industrial,agricultural, and aquaculture production. Its shallow depths imply that the effect of wind stress onsea level becomes appreciable in driving storm surges even during enhanced Southwest Monsoonand the passage of moderate storms.Using a dispersive long-wave model coupled with the significant wave model of the CoastalEngineering Research Center (CERC), the occurrence of potentially devastating storm surgeflooding around Manila Bay was numerically simulated. A unique characteristic of the new modelis the inclusion of the dispersive terms in the associated momentum balance equations. Deepwater gravity waves are always dispersive and inclusion of the dispersive terms is expected toprovide more accurate modelling results.The predictive capability of the model was verified using observations during the passage ofseveral storms including Typhoon Milenyo (2006) and Typhoon Pedring (2011). The occurrenceof the anomalously high storm surge of about 2.5 metres during the passage of Typhoon Pedringfar north of the area was correctly simulated. Numerical integration of the dispersive long-wavemodel with the addition of higher order terms in the momentum balance appears to give accuratepredictions of the coastal flooding due to storm surges and waves.The hydrodynamic set-down which occurs in many coastal areas during strong typhoons can besimulated well by the model. A new empirical model for the hydrodynamic force exerted by thecombined action of storm surges, waves, and extreme currents is also presented. Initial calculationsof hydrodydynamic forces generated by an actual typhoon crossing Manila Bay are discussed.


MAUSAM ◽  
2021 ◽  
Vol 49 (4) ◽  
pp. 453-460
Author(s):  
ASOI LAL ◽  
R. S. SUNDAR

Whenever a vortex or system of low or depression forms over head bay during Monsoon months, the west coast experiences heavy rainfall. These heavy rainfall occurrences are usually higher than the normal rainfall. An attempt has been made in this study to visualise the easterly wave model during monsoon months with the help of satellite imageries. The rain is expected heavy and wide spread over Madhya Maharashtra and South Gujarat when third sector of the wave covers these areas, as visualised in satellite wave and depression or vortex lies in the 5th or 6th sector of the wave.


2021 ◽  
Vol 5 (4) ◽  
pp. 274
Author(s):  
Jinfeng Wang ◽  
Baoli Yin ◽  
Yang Liu ◽  
Hong Li ◽  
Zhichao Fang

In this article, a new mixed finite element (MFE) algorithm is presented and developed to find the numerical solution of a two-dimensional nonlinear fourth-order Riemann–Liouville fractional diffusion-wave equation. By introducing two auxiliary variables and using a particular technique, a new coupled system with three equations is constructed. Compared to the previous space–time high-order model, the derived system is a lower coupled equation with lower time derivatives and second-order space derivatives, which can be approximated by using many time discrete schemes. Here, the second-order Crank–Nicolson scheme with the modified L1-formula is used to approximate the time direction, while the space direction is approximated by the new MFE method. Analyses of the stability and optimal L2 error estimates are performed and the feasibility is validated by the calculated data.


Author(s):  
Tuğbanur DİNÇER ◽  
Ozgur Ozcan

Abstract This paper identifies pre-service physics teachers’ mental models of the concept of the electric field. The models were determined by means of five contexts all of which were supported with sets of experiments. The contexts examined were (1) the effect of the electric field on the insulator, (2) the comparison of the conductor and insulator in the electric field, (3) the effect of the electric field on the neutral conductor and insulator, (4) the effect of the electric field on the conductor liquid, and (5) the effect of the conductor and insulators materials forming a closed surface on the electric field. Semi-structured interviews related to the contexts were conducted with the 22 pre-service physics teachers. The data collected throughout the interviews were put to content analysis and thus, the pre-service teachers’ mental models were identified. In total, six mental models were identified. One model was a scientific model (Scientific Model of the Electric Field (SMEF)) and five of which were unscientific models (Magnetic-Based Field Model (MBFM), Mechanical Wave Model (MWM), Material Independent Field Model (MIFM), Force-Free Field Model (FFFM) and Force-Based Field Model (FBFM)) were identified. It became apparent as a result of document analysis that several unscientific mental models were also included in resource books. Approximately one and a half years later, almost all students were interviewed again about the contexts so as to find whether or not their models were permanent or not. Following the interviews, their mental models were found to be quite permanent and to be time-independent.


Author(s):  
S. Saha Ray ◽  
Shailendra Singh

The governing equations for fluid flows, i.e. Kadomtsev–Petviashvili–Benjamin–Bona–Mahony (KP-BBM) model equations represent a water wave model. These model equations describe the bidirectional propagating water wave surface. In this paper, an auto-Bäcklund transformation is being generated by utilizing truncated Painlevé expansion method for the considered equation. This paper determines the new bright soliton solutions for [Formula: see text] and [Formula: see text]-dimensional nonlinear KP-BBM equations. The simplified version of Hirota’s technique is utilized to infer new bright soliton solutions. The results are plotted graphically to understand the physical behavior of solutions.


2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Michal Švanda ◽  
Anna Smičková ◽  
Tatiana Výbošťoková

AbstractWe investigate the maximum expected magnitudes of the geomagnetically induced currents (GICs) in the Czech transmission power network. We compute a model utilising the Lehtinen–Pirjola method, considering the plane-wave model of the geoelectric field, and using the transmission network parameters kindly provided by the operator. We find that the maximum amplitudes expected in the nodes of the Czech transmission grid during the Halloween storm-like event are about 15 A. For the “extreme-storm” conditions with a 1-V/km geoelectric field, the expected maxima do not exceed 40 A. We speculate that the recently proven statistical correlation between the increased geomagnetic activity and anomaly rate in the power grid may be due to the repeated exposure of the devices to the low-amplitude GICs. Graphical Abstract


2021 ◽  
Vol 18 (6) ◽  
pp. 984-994
Author(s):  
Guangquan Li ◽  
Chaodi Xie

Abstract Previously, hydrogeologists and petroleum engineers use seepage experiments to measure permeability. This paper develops a novel method to calculate matrix permeability from velocity and attenuation of an ultrasonic S-wave. At first, permeability is derived as a function of frequency when an S-wave scans a fluid-saturated rock. Substituting the permeability into a previous S-wave model gives theoretical velocity and attenuation, in which the nexus parameter is the average distance of aperture representing pores. Fitting the predicted velocity and quality factor against the measured counterparts yields permeability in the full frequency range. For Berea sandstone, the inverted permeability at low frequency (0.0376 Darcy) is comparable to Darcy permeability (0.075 Darcy), confirming that Berea sandstone is homogenous. For Boise sandstone, the inverted permeability at low frequency is 0.0457 Darcy, much lower than Darcy permeability (1 Darcy). When S-wave scans the rocks, its velocity and attenuation are dominated by matrix pore throats and the inverted permeability represents matrix permeability. Unlike Berea sandstone, Boise sandstone has fractures and widely distributed grain diameters. The fractures and the large pores (due to large grain diameter) are preferential pathways that increase Darcy permeability far more than matrix permeability.


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