scholarly journals 1D–2D Numerical Model for Wave Attenuation by Mangroves as a Porous Structure

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 66
Author(s):  
Ikha Magdalena ◽  
Vivianne Kusnowo ◽  
Moh. Ivan Azis ◽  
Widowati
Keyword(s):  
Porous Media ◽  
Transmission Coefficient ◽  
Numerical Scheme ◽  
Wave Attenuation ◽  
Separation Of Variables ◽  
Coastal Protection ◽  
Diffusion Term ◽  
Central Java ◽  
Friction Term ◽  
Volume Method

In this paper, we investigate wave attenuation caused by mangroves as a porous media. A 1-D mathematical model is derived by modifying the shallow water equations (SWEs). Two approaches are used to involve the existing of mangrove: friction term and diffusion term. The model will be solved analytically using the separation of variables method and numerically using a staggered finite volume method. From both methods, wave transmission coefficient will be obtained and used to observe the damping effect induced by the porous media. Several comparisons are shown to examine the accuracy and robustness of the derived numerical scheme. The results show that the friction coefficient, diffusion coefficient and vegetation’s length have a significant effect on the transmission coefficient. Moreover, numerical observation is extended to a 2-D SWEs, where we conduct a numerical simulation over a real bathymetry profile. The results from the 2-D numerical scheme will be validated using the data obtained from the field measurement which took place in Demak, Central Java, Indonesia. The results from this research will be beneficial to determine the characteristics of porous structures used for coastal protection.

scholarly journals Wave Transmission by Rectangular Submerged Breakwaters

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 56
Author(s):  
Ikha Magdalena ◽  
Muh Fadhel Atras ◽  
Leo Sembiring ◽  
M. A. Nugroho ◽  
Roi Solomon B. Labay ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Transmission Coefficient ◽  
Numerical Scheme ◽  
Separation Of Variables ◽  
Staggered Grid ◽  
Incoming Wave ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Before And After ◽  
Volume Method

In this paper, we investigate the wave damping mechanism caused by the presence of submerged bars using the Shallow Water Equations (SWEs). We first solve these equations for the single bar case using separation of variables to obtain the analytical solution for the wave elevation over a rectangular bar wave reflector with specific heights and lengths. From the analytical solution, we derive the wave reflection and transmission coefficients and determine the optimal height and length of the bar that would give the smallest transmission coefficient. We also measure the effectiveness of the bar by comparing the amplitude of the incoming wave before and after the wave passes the submerged bar, and extend the result to the case of n-submerged bars. We then construct a numerical scheme for the SWEs based on the finite volume method on a staggered grid to simulate the propagation of a monochromatic wave as it passes over a single submerged rectangular bar. For validation, we compare the transmission coefficient values obtained from the analytical solution, numerical scheme, and experimental data. The result of this paper may be useful in wave reflector engineering and design, particularly that of rectangle-shaped wave reflectors, as it can serve as a basis for designing bar wave reflectors that reduce wave amplitudes optimally.

Wave Interaction with an Emerged Porous Media

2014 ◽  
Vol 6 (5) ◽  
pp. 680-692 ◽  
Author(s):  
I. Magdalena ◽  
S. R. Pudjaprasetya ◽  
L. H. Wiryanto
Keyword(s):  
Porous Media ◽  
Wave Reflection ◽  
Wave Interaction ◽  
Staggered Grid ◽  
Transmission Curve ◽  
Reflection And Transmission ◽  
Reflection And Transmission Coefficient ◽  
Friction Term ◽  
Horizontal Flux ◽  
Volume Method

AbstractIn this paper, we study wave interaction with an emerged porous media. The governing equation is shallow water equations with a friction term of the linearized Dupuit-Forcheimer’s formula. From the continuity of surface and horizontal flux, we derived the wave reflection and transmission coefficient formulas. They are similar with the corresponding formulas of the submerged solid bar breakwater. We solve the equations numerically using finite volume method on a staggered grid. The numerical wave reduction in the porous media confirms the analytical wave transmission curve.

scholarly journals Representative Transmission Coefficient for Evaluating the Wave Attenuation Performance of 3D Floating Breakwaters in Regular and Irregular Waves

2021 ◽  
Vol 9 (4) ◽  
pp. 388
Author(s):  
Huu Phu Nguyen ◽  
Jeong Cheol Park ◽  
Mengmeng Han ◽  
Chien Ming Wang ◽  
Nagi Abdussamie ◽  
...  
Keyword(s):  
Transmission Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Transmitted Wave ◽  
Irregular Waves ◽  
Hydrodynamic Analysis ◽  
Evaluation Approach ◽  
Floating Breakwater ◽  
Floating Breakwaters ◽  
Evaluation Approaches

Wave attenuation performance is the prime consideration when designing any floating breakwater. For a 2D hydrodynamic analysis of a floating breakwater, the wave attenuation performance is evaluated by the transmission coefficient, which is defined as the ratio between the transmitted wave height and the incident wave height. For a 3D breakwater, some researchers still adopted this evaluation approach with the transmitted wave height taken at a surface point, while others used the mean transmission coefficient within a surface area. This paper aims to first examine the rationality of these two evaluation approaches via verified numerical simulations of 3D heave-only floating breakwaters in regular and irregular waves. A new index—a representative transmission coefficient—is then presented for one to easily compare the wave attenuation performances of different 3D floating breakwater designs.

scholarly journals Spatial-Planning-Based Ecosystem Adaptation (SPBEA): A Concept and Modeling of Prone Shoreline Retreat Areas

2021 ◽  
Vol 10 (3) ◽  
pp. 176
Author(s):  
Dewayany Sutrisno ◽  
Mulyanto Darmawan ◽  
Ati Rahadiati ◽  
Muhammad Helmi ◽  
Armaiki Yusmur ◽  
...  
Keyword(s):  
Spatial Planning ◽  
Best Practice ◽  
Model Development ◽  
Multicriteria Analysis ◽  
Climate Change Impacts ◽  
Coastal Protection ◽  
Adaptation To Climate Change ◽  
Shoreline Retreat ◽  
Tidal Waves ◽  
Central Java

Ecosystem-based adaptation to climate change impacts, such as shoreline retreat, has been promoted at the international, national, and even local levels. However, among scientists, opinions about how to implement it in spatial-planning practices are varied. Science-based environmental factors, human wellbeing, and sustainable development can be strengthened by developing spatial-planning-based ecosystem adaptations (SPBEAs). Therefore, this article aims to assess how the SPBEA model can be developed within an area prone to shoreline retreat. A coastal area of the Sayung subdistrict in Central Java, Indonesia, was selected as a study area because it has experienced a massive shoreline retreat. A multicriteria analysis (MCA) method was employed for developing the model by using the geographic information system (GIS) technique of analysis, divided into three steps: the fishpond zone determination, which involved the analytical hierarchy process (AHP) method in the process of model development; the fishpond site determination; SPBEA fishpond site development. The results show that the SPBEA model is the best practice solution for combatting shoreline retreat because of tidal waves and/or sea-level rise. The spatial site management should empower the coastal protection zone and the sustainable fishpond zone by implementing a silvofishery approach.

scholarly journals Resonant Periods of Seiches in Semi-Closed Basins with Complex Bottom Topography

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 181
Author(s):  
Ikha Magdalena ◽  
Nadhira Karima ◽  
Hany Qoshirotur Rif’atin
Keyword(s):  
Separation Of Variables ◽  
Bottom Topography ◽  
Small Error ◽  
Staggered Grid ◽  
Resonant Wave ◽  
Wave Elevation ◽  
External Forces ◽  
Volume Method ◽  
Resonant Period ◽  
Wave Induced

Seiches and resonances are two closely related phenomena that can cause damage to coastal areas. Seiches that occur in a basin at a distinct period named the resonant period may generate resonance when a wave induced by external forces enters the basin and has the same period as the seiches. Studying this period has become essential if we want to understand the resonance better. Thus, in this paper, we derive the resonant period in various shapes of semi-closed basin using the shallow water equations. The equations are then solved analytically using the separation of variables method and numerically using the finite volume method on staggered grid to discover the resonant period for each basin. To validate the numerical scheme, we compare its results against the analytical resonant periods, resulting in a very small error for each basin, suggesting that the numerical model is quite reliable in the estimation of the analytical resonant period. Further, resonant wave profiles are also observed. It is revealed that, in the coupled rectangular basin, the maximum wave elevation is disproportionate to the ratio of the length of the basin, while, in the trapezoidal basin, the ratio of the depth of the basin has no significant impact on the maximum wave elevation.

scholarly journals MHDSTS: a new explicit numerical scheme for simulations of partially ionised solar plasma

2018 ◽  
Vol 615 ◽  
pp. A67 ◽  
Author(s):  
P. A. González-Morales ◽  
E. Khomenko ◽  
T. P. Downes ◽  
A. de Vicente
Keyword(s):  
Numerical Scheme ◽  
Operator Splitting ◽  
Conservation Equation ◽  
Ambipolar Diffusion ◽  
Point Of View ◽  
Integration Time ◽  
Solar Photosphere ◽  
Time Step ◽  
Diffusion Term ◽  
Fluid Approximation

The interaction of plasma with magnetic field in the partially ionised solar atmosphere is frequently modelled via a single-fluid approximation, which is valid for the case of a strongly coupled collisional media, such as solar photosphere and low chromosphere. Under the single-fluid formalism the main non-ideal effects are described by a series of extra terms in the generalised induction equation and in the energy conservation equation. These effects are: Ohmic diffusion, ambipolar diffusion, the Hall effect, and the Biermann battery effect. From the point of view of the numerical solution of the single-fluid equations, when ambipolar diffusion or Hall effects dominate can introduce severe restrictions on the integration time step and can compromise the stability of the numerical scheme. In this paper we introduce two numerical schemes to overcome those limitations. The first of them is known as super time-stepping (STS) and it is designed to overcome the limitations imposed when the ambipolar diffusion term is dominant. The second scheme is called the Hall diffusion scheme (HDS) and it is used when the Hall term becomes dominant. These two numerical techniques can be used together by applying Strang operator splitting. This paper describes the implementation of the STS and HDS schemes in the single-fluid code MANCHA3D. The validation for each of these schemes is provided by comparing the analytical solution with the numerical one for a suite of numerical tests.

A NUMERICAL ANALYSIS OF A REACTION–DIFFUSION SYSTEM MODELING THE DYNAMICS OF GROWTH TUMORS

2010 ◽  
Vol 20 (05) ◽  
pp. 731-756 ◽  
Author(s):  
VERÓNICA ANAYA ◽  
MOSTAFA BENDAHMANE ◽  
MAURICIO SEPÚLVEDA
Keyword(s):  
Weak Solution ◽  
Numerical Analysis ◽  
Numerical Scheme ◽  
System Modeling ◽  
Reaction Diffusion ◽  
Reaction Diffusion System ◽  
Diffusion System ◽  
Existence Of Weak Solutions ◽  
Early Tumor ◽  
Volume Method

We consider a reaction–diffusion system of 2 × 2 equations modeling the spread of early tumor cells. The existence of weak solutions is ensured by a classical argument of Faedo–Galerkin method. Then, we present a numerical scheme for this model based on a finite volume method. We establish the existence of discrete solutions to this scheme, and we show that it converges to a weak solution. Finally, some numerical simulations are reported with pattern formation examples.

A simple constitutive model for predicting the pressure histories developed behind rigid porous media impinged by shock waves

2013 ◽  
Vol 718 ◽  
pp. 507-523 ◽  
Author(s):  
O. Ram ◽  
O. Sadot
Keyword(s):  
Shock Wave ◽  
Porous Medium ◽  
Porous Media ◽  
Shock Waves ◽  
Constitutive Model ◽  
Wave Attenuation ◽  
Front Face ◽  
Viscous Effects ◽  
Pressure History ◽  
Target Wall

AbstractShock wave attenuation by means of rigid porous media is often applied when protective structures are dealt with. The passage of a shock wave through a layer of porous medium is accompanied by diffractions and viscous effects that attenuate and weaken the transmitted shock, thus reducing the load that develops on the target wall that is placed behind the protective layer. In the present study, the parameters governing the pressure build-up on the target wall are experimentally investigated using a shock tube facility. Different porous samples are impinged by normal shock waves of various strengths and the subsequent pressure histories that are developed on the target wall are recorded. In addition, different standoff distances from the target wall are investigated. Assuming that the flow through the porous medium is close to being isentropic enabled us to develop a general constitutive model for predicting the pressure history developed on the target wall. This model can be applied to predict the pressure build-up on the target wall for any pressure history that is imposed on the front face of the porous sample without the need to conduct numerous experiments. Results obtained by other investigators are found to be in very good agreement with the predictions of the presently developed constitutive model.

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