Surface gravity wave interaction with a submerged composite wavy porous plate attached to a vertical wall

2021 ◽  
pp. 1-23
Author(s):  
Amar Kumar Mohapatra ◽  
Trilochan Sahoo
Keyword(s):  
Wave Height ◽  
Vertical Wall ◽  
Porous Plate ◽  
Hydrodynamic Performance ◽  
Darcy Law ◽  
Wave Number ◽  
Relative Amplitude ◽  
Hydrodynamic Characteristics ◽  
Physical Parameters ◽  
Submergence Depth

Abstract The hydrodynamic performance of composite wavy submerged porous plate attached to a wall is investigated using numerical method MDBEM (Multi-domain boundary element method) in the linearized water wave theory in which wave past the porous barriers are modelled using Darcy law. Effect of the presence of wall on the hydrodynamic parameters like reflection coefficient, dimensionless wave height, wave force and moment acting on the composite wavy porous structure and horizontal force on the vertical rigid wall is analyzed for various physical parameters like the number of ripple wavelength, structural porosity, submergence depth and relative amplitude of composite wavy porous plate. The study demonstrates that the efficiency of hydrodynamic characteristics of the composite wavy porous plate attached to the wall is better compared to a horizontal porous plate attached to the wall of the same applicability conditions (around 27% reduction in wave reflection). Moreover, optimum performance of this kind of breakwater system is increased by considering the lower submergence, higher relative ripple amplitude, appropriate relative amplitude and suitable moderate porosity of the structure in the range of wave number 1 < k0h < 5. Dimensionless wave height, horizontal load on the impermeable wall are reduced to zero, whilst substantial minimization of vertical load on the structure with suitable consideration of the other influencing parameters of porosity Gp = 0.3, relative amplitude Ds/h = 0.1, relative ripple wavelength m > 3 and submergence depth h1/h = 0.3. The present structural arrangement will be useful for attenuating wave effects on the sea wall.

Unsteady MHD Free Convective Heat and Mass Transfer Flow Past a Vertical Porous Plate in the Presence of Radiation and Chemical Reaction

2017 ◽  
Vol 6 (10) ◽  
pp. 116
Author(s):  
J. Buggaramulu ◽  
M. Venkatakrishna ◽  
Y. Harikrishna
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Chemical Reaction ◽  
Porous Plate ◽  
Physical Parameters ◽  
Governing Equations ◽  
Vertical Porous Plate ◽  
Flow Past ◽  
Transfer Flow

The objective of this paper is to analyze an unsteady MHD free convective heat and mass transfer boundary flow past a semi-infinite vertical porous plate immersed in a porous medium with radiation and chemical reaction. The governing equations of the flow field are solved numerical a two term perturbation method. The effects of the various parameters on the velocity, temperature and concentration profiles are presented graphically and values of skin-frication coefficient, Nusselt number and Sherwood number for various values of physical parameters are presented through tables.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

scholarly journals MACH-REFLECTION AS A DIFFRACTION PROBLEM

1976 ◽  
Vol 1 (15) ◽  
pp. 45 ◽  
Author(s):  
Udo Berger ◽  
Soren Kohlhase
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Water Waves ◽  
Gas Dynamics ◽  
Mach Reflection ◽  
Diffraction Problem ◽  
Vertical Wall ◽  
Oblique Wave ◽  
Wave Heights ◽  
The Waves

As under oblique wave approach water waves are reflected by a vertical wall, a wave branching effect (stem) develops normal to the reflecting wall. The waves progressing along the wall will steep up. The wave heights increase up to more than twice the incident wave height. The £jtudy has pointed out that this effect, which is usually called MACH-REFLECTION, is not to be taken as an analogy to gas dynamics, but should be interpreted as a diffraction problem.

MHD flow, under the kinetic postulate, of fluids that are initially liquid under thermal radiation effects

2019 ◽  
Vol 97 (6) ◽  
pp. 579-587
Author(s):  
Azad Hussain ◽  
Zainia Muneer ◽  
M.Y. Malik ◽  
Saadia Ghafoor
Keyword(s):  
Nusselt Number ◽  
Differential Equations ◽  
Thermal Radiation ◽  
Skin Friction ◽  
Radiation Effects ◽  
Shooting Method ◽  
Porous Plate ◽  
Mhd Flow ◽  
Physical Parameters ◽  
Runge Kutta Method

The present study focuses on the non-Newtonian magnetohydrodynamic flow, under the kinetic postulate, of fluids that are initially liquid past a porous plate in the appearance of thermal radiation effects. Resemblance transfigurations are used to metamorphose the governing equations for temperature and velocity into a system of ordinary differential equations. We then solved these differential equations subject to convenient boundary conditions by using the shooting method along with the Runge–Kutta method. Heat transfer and characteristic flow results are acquired for different compositions of physical parameters. These results are extended graphically to demonstrate interesting attributes of the physics of the problem. Nusselt number and skin friction coefficients are also discussed via graphs and tables for different values of dimensionless parameters. Decline occurs in velocity profile due to escalating values of M. Temperature profile depicts growing behavior due to acceleration in the values of λ and M. Nusselt number and skin friction curves represent rising behavior according to their parameters.

Numerical investigation of hydrodynamic characteristics of fish-like undulation using the adaptive dynamic-grid method

2021 ◽  
pp. 2150299
Author(s):  
Zeyu Guo ◽  
Gucheng Zhu ◽  
Zuogang Chen ◽  
Yukun Feng
Keyword(s):  
Frictional Force ◽  
Control Method ◽  
Turbulent Viscosity ◽  
Flow Characteristics ◽  
Grid Method ◽  
Wave Number ◽  
Hydrodynamic Characteristics ◽  
Substantial Impact ◽  
Vortex Patterns ◽  
Undulatory Swimming

To investigate the hydrodynamics of undulatory swimming, a key issue in numerical analysis is to determine the correlation between undulatory locomotion and the flow characteristics. In this study, a novel dynamic-grid generation method, the adaptive control method, is implemented to deal with the moving and morphing boundaries in an unsteady flow field at all Reynolds numbers. This method, based on structured grids, can ensure the orthogonality and absolute controllability of the grids and is performed to precisely simulate the wake and the boundary layer. The NACA0010 wing is employed as a two-dimensional (2D) body model of a fish in the simulations. To maintain the calculation stability, the increase stage of the amplitude is defined as a smooth transitional stage. Analysis of hydrodynamic coefficients reveals that undulation results in a significant increase of frictional force in laminar flow [Formula: see text]. However, the undulation also results in a reduction of the frictional force when the fish swims in turbulent flow [Formula: see text]. The vorticity distribution and the [Formula: see text]-criterion are both used to accurately capture the shedding vortexes in the wake. Furthermore, these vortex pairs have a substantial impact on the turbulence and the wake, in which the turbulent kinetic energy and the turbulent viscosity ratio both decrease at [Formula: see text]. The wake of an undulatory fish presents different vortex patterns with various kinematic parameters. When the phase velocity is greater than the incoming velocity and the wave number is sufficiently large, thrust is yielded, accompanying the distinct reverse Karman Street in the wake.

Numerical Modelling of a Heaving Point Absorber in Front of a Vertical Wall

2013 ◽  
Author(s):  
Julius Schay ◽  
Joydip Bhattacharjee ◽  
C. Guedes Soares
Keyword(s):  
Numerical Modeling ◽  
Numerical Modelling ◽  
Vertical Wall ◽  
Large Body ◽  
Hydrodynamic Performance ◽  
Large Structure ◽  
Energy Converter ◽  
Point Absorber ◽  
Individual Point ◽  
Heading Angle

The hydrodynamic performance of a heaving point absorber as a wave energy converter near a large body is studied through numerical modeling. First the study is performed for an individual point absorber in the absence of large structure and the results are compared with the results available in the literature. Next, the performance of a point absorber floating in the vicinity of a large body, which is considered as a fixed vertical wall, is investigated. The efficiency of the power absorption in regular and irregular seas is examined based on different floater sizes, floater shapes, drafts, wave heading angle and positioning of the floater. Numerical simulations are based on hydrodynamic forces and coefficients, obtained with the commercial software WAMIT.

scholarly journals Peristaltic viscoelastic fluid motion in a tube

2001 ◽  
Vol 26 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Elsayed F. Elshehawey ◽  
Ayman M. F. Sobh
Keyword(s):  
Amplitude Ratio ◽  
Fluid Motion ◽  
Perturbation Expansion ◽  
Pressure Rise ◽  
Weissenberg Number ◽  
Wave Number ◽  
Physical Parameters ◽  
Oldroyd Fluid ◽  
Pumping Rate ◽  
Axisymmetric Tube

Peristaltic motion of viscoelastic incompressible fluid in an axisymmetric tube with a sinusoidal wave is studied theoretically in the case that the radius of the tube is small relative to the wavelength. Oldroyd flow has been considered in this study and the problem is formulated and analyzed using a perturbation expansion in terms of the variation of the wave number. This analysis can model the chyme movement in the small intestine by considering the chyme as an Oldroyd fluid. We found out that the pumping rate of Oldroyd fluid is less than that for a Newtonian fluid. Further, the effects of Reynolds number, Weissenberg number, amplitude ratio and wave number on the pressure rise and friction force have been discussed. It is found that the pressure rise does not depend on Weissenberg number at a certain value of flow rate. The results are studied for various values of the physical parameters of interest.

Characteristics of OWC Type WEC Dampers Installed on a Very Large Floating Structure

2020 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shoichiro Furuya ◽  
Yasuhiro Aida ◽  
Koichi Masuda ◽  
Hiroaki Eto
Keyword(s):  
Wave Energy ◽  
Sea Water ◽  
Prediction Method ◽  
Hydrodynamic Performance ◽  
Floating Body ◽  
Hydrodynamic Characteristics ◽  
Linear Potential ◽  
Floating Structure ◽  
Combined System ◽  
Floating System

Abstract Oscillating water column (OWC) type wave energy converters (WECs) have been researched and developed. OWC WECs are relatively friendly to maintain them in operation because all of mechanical units are set above a sea water surface. In addition, a feature of an OWC device is similar to an air dumper system. Thus, it should be possible not only to harvest wave energy but also to reduce motion of a floating system at the same time. As well as WEC system should be used with other ocean renewable energies as a combined system. This paper describes hydrodynamic characteristics of OWC devices and wave fields around them of multi-OWC devices equipped large floating structures. For this research, the linear potential theory based in-house programme code was applied to calculate hydrodynamic performance of OWC regions and elastic motion behaviours of the structures. Besides, calculation results were compared with some experimental results of characteristics of OWC devices on reference papers published. Then we proved validity of the calculation method. We have quantitatively summarized how much the reduction effect can be seen according to the aircushion placement and the number of aircushions on the floating body. the paper investigated arrangement of OWC devices on the floating structure with several variations. Using the prediction method, effects of arrangement of OWC devices on the performances are investigated.

Experimental Study on Hydrodynamics of Hybrid Deep-V Monohull With Different Built-Up Appendages

2018 ◽  
Author(s):  
Shuzheng Sun ◽  
Hui Li ◽  
Muk Chen Ong
Keyword(s):  
Model Test ◽  
Performance Model ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Hydrodynamic Characteristics ◽  
Vertical Acceleration ◽  
Test Results ◽  
Regular Waves ◽  
Sea State ◽  
Seakeeping Performance

The hydrodynamic characteristics of a hybrid deep-V monohull with different built-up appendages are investigated experimentally in order to improve the resistance and seakeeping performance. Model tests have been carried out to study the hydrodynamic performance between a bare deep-V vessel and a deep-V monohull with different built-up appendage configurations (i.e. a hybrid deep-V monohull). From the model test results, it is found that the existence of the appendages will reduce the amplitude of pitching angle and bow vertical acceleration compared to that of the bare deep-V vessel in heading regular waves. However, the resistances for the hybrid deep-V monohull with built-up appendages are increased 15.6% for Fn = 0.264, and 0.1% for Fn = 0.441 compared to the resistance of the bare deep-V vessel. The model test results of seakeeping performance in irregular waves show that the hybrid deep-V monohull gives a better seakeeping performance than the deep-V vessel. The pitching angle and bow vertical acceleration of the hybrid deep-V monohull containing a built-up appendage are reduced 15.3% and 20.6% compared to the deep-V monohull in irregular waves at Fn = 0.441 in 6th class sea state (H1/3 = 6m).

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