scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS (SPH) IN NEARSHORE MIXING: A COMPARISON TO LABORATORY DATA

Author(s):  
Soroush Abolfathi ◽  
Jonathan Pearson

A weakly compressible smoothed particle hydrodynamics (WCSPH) method is used to simulate the nearshore flow hydrodynamics. The wave induced dispersion and diffusion are determined for monochromatic waves with significant wave height of 0.12 m and the wave period of 1.2 sec (Sop=5%) based on WCSPH wave dynamics. The hydrodynamics of WCSPH model are compared to the laboratory results obtained from series of LDA measurements. The overall mixing coefficients across the nearshore are determined from WCSPH hydrodynamics. The mixing coefficients obtained are compared with the values determined from a series of fluorometric studies performed in a large-scale facility in DHI, Denmark. The results show that the wave profiles are in good agreement with the experimental data. The WCSPH model is proven to be well capable of estimating the dispersion across the nearshore.

2018 ◽  
Vol 19 (2) ◽  
pp. 172-181
Author(s):  
Muhammad Zahir Ramli

ABSTRACT: An implementation of the weakly compressible smoothed particle hydrodynamics (WCSPH) method is demonstrated to determine the hydrodynamics coefficients through radiation problem of an oscillating 2D rectangular box. Three possible modes of motion namely swaying, heaving, and rolling are carried out to establish the influence of oscillating motions in predicting the added mass and damping. Both solid boundary and fluid flow are modelled by WCSPH and validated by the potential flow and experimental results. Discrepancies observed at lower frequencies are further investigated using different particle resolutions, different time steps, and extending the domain with longer runtime to demonstrate the performance of WCSPH. Finally, flow separation and vortices are discussed and compared with experimental results. ABSTRAK: Bagi fenomena yang melibatkan radiasi dalam air, segiempat kotak 2D diosilasikan dengan menggunakan simulasi WCSPH untuk memperoleh pekali hidrodinamik. Mod osilasi terbahagi kepada 3 iaitu sway, heave dan roll. Osilasi dengan mengguna pakai kotak akan mempengaruhi pergerakan air dalam menentukan nilai penambahan jisim dan rendaman. Keseluruhan domain air dan sempadan telah dimodelkan dengan menggunakan WCSPH. Semua model tersebut kemudiannya akan dibandingkan melalui keputusan eksperimen dan teori. Jika keputusan melalui kaedah WCSPH ini berbeza, terutama pada frekuensi rendah, penyelidikan lanjut akan dilakukan dengan menggunakan zarah resolusi yang berbeza, langkah masa yang berbeza dan menambah masa domain ujikaji bagi menilai keputusan WCSPH. Akhirnya, kriteria aliran dan kadar pusaran yang terhasil di sekeliling kotak akan dibincang dan dibandingkan bersama keputusan eksperimen.


Author(s):  
Siti Ayishah Thaminah Hikmatullah Sahib ◽  
Muhammad Zahir Ramli ◽  
Muhammad Afiq Azman ◽  
Muhammad Mazmirul Abd Rahman ◽  
Mohd Fuad Miskon ◽  
...  

AbstractIn many cases of wave structure interactions, three-dimensional models are used to demonstrate real-life complex environments in large domain scales. In the seakeeping context, predicting the motion responses in the interaction of a long body resembling a ship structure with regular waves is crucial and can be challenging. In this work, regular waves interacting with a rigid floating structure were simulated using the open-source code based on the weakly compressible smoothed particle hydrodynamics (WCSPH) method, and optimal parameters were suggested for different wave environments. Vertical displacements were computed, and their response amplitude operators (RAOs) were found to be in good agreement with experimental, numerical, and analytical results. Discrepancies of numerical and experimental RAOs tended to increase at low wave frequencies, particularly at amidships and near the bow. In addition, the instantaneous wave contours of the surrounding model were examined to reveal the effects of localized waves along the structure and wave dissipation. The results indicated that the motion response from the WCSPH responds well at the highest frequency range (ω > 5.235 rad/s).


Author(s):  
Steven J. Lind ◽  
Benedict D. Rogers ◽  
Peter K. Stansby

This paper presents a review of the progress of smoothed particle hydrodynamics (SPH) towards high-order converged simulations. As a mesh-free Lagrangian method suitable for complex flows with interfaces and multiple phases, SPH has developed considerably in the past decade. While original applications were in astrophysics, early engineering applications showed the versatility and robustness of the method without emphasis on accuracy and convergence. The early method was of weakly compressible form resulting in noisy pressures due to spurious pressure waves. This was effectively removed in the incompressible (divergence-free) form which followed; since then the weakly compressible form has been advanced, reducing pressure noise. Now numerical convergence studies are standard. While the method is computationally demanding on conventional processors, it is well suited to parallel processing on massively parallel computing and graphics processing units. Applications are diverse and encompass wave–structure interaction, geophysical flows due to landslides, nuclear sludge flows, welding, gearbox flows and many others. In the state of the art, convergence is typically between the first- and second-order theoretical limits. Recent advances are improving convergence to fourth order (and higher) and these will also be outlined. This can be necessary to resolve multi-scale aspects of turbulent flow.


Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.


2019 ◽  
Vol 144 ◽  
pp. 101481 ◽  
Author(s):  
R.J. Lowe ◽  
M.L. Buckley ◽  
C. Altomare ◽  
D.P. Rijnsdorp ◽  
Y. Yao ◽  
...  

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xiao Nie ◽  
Leiting Chen ◽  
Tao Xiang

We present a novel Smoothed Particle Hydrodynamics (SPH) based algorithm for efficiently simulating compressible and weakly compressible particle fluids. Prior particle-based methods simulate all fluid particles; however, in many cases some particles appearing to be at rest can be safely ignored without notably affecting the fluid flow behavior. To identify these particles, a novel sleepy strategy is introduced. By utilizing this strategy, only a portion of the fluid particles requires computational resources; thus an obvious performance gain can be achieved. In addition, in order to resolve unphysical clumping issue due to tensile instability in SPH based methods, a new artificial repulsive force is provided. We demonstrate that our approach can be easily integrated with existing SPH based methods to improve the efficiency without sacrificing visual quality.


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