PREDICTION OF HYDRODYNAMIC PERFORMANCE OF 3-D WIG BY IBEM

2021 ◽  
Vol 160 (A3) ◽  
Author(s):  
S Bal
Keyword(s):  
Free Surface ◽  
Water Surface ◽  
Three Dimensional ◽  
Free Water ◽  
Hydrodynamic Performance ◽  
Ground Vehicle ◽  
Surface Part ◽  
Free Water Surface ◽  
Constant Strength ◽  
Lift And Drag

The hydrodynamic performance of three-dimensional WIG (Wing-In-Ground) vehicle moving with a constant speed above free water surface has been predicted by an Iterative Boundary Element Method (IBEM). IBEM originally developed for 3-D hydrofoils moving under free surface has been modified and extended to 3-D WIGs moving above free water surface. The integral equation based on Green's theorem can be divided into two parts: (1) the wing part, (2) free surface part. These two problems are solved separately, with the effects of one on the other being accounted for in an iterative manner. Both the wing part including the wake surface and the free surface part have been modelled with constant strength dipole and source panels. The effects of Froude number, the height of the hydrofoil from free surface, the sweep, dihedral and anhedral angles on the lift and drag coefficients are discussed for swept and V-type WIGs.

Prediction of Hydrodynamic Performance of 3-D WIG by IBEM

2018 ◽  
Vol Vol 160 (A3) ◽  
Author(s):  
S Bal
Keyword(s):  
Free Surface ◽  
Water Surface ◽  
Three Dimensional ◽  
Free Water ◽  
Hydrodynamic Performance ◽  
Ground Vehicle ◽  
Surface Part ◽  
Free Water Surface ◽  
Constant Strength ◽  
Lift And Drag

The hydrodynamic performance of three-dimensional WIG (Wing-In-Ground) vehicle moving with a constant speed above free water surface has been predicted by an Iterative Boundary Element Method (IBEM). IBEM originally developed for 3-D hydrofoils moving under free surface has been modified and extended to 3-D WIGs moving above free water surface. The integral equation based on Green's theorem can be divided into two parts: (1) the wing part, (2) free surface part. These two problems are solved separately, with the effects of one on the other being accounted for in an iterative manner. Both the wing part including the wake surface and the free surface part have been modelled with constant strength dipole and source panels. The effects of Froude number, the height of the hydrofoil from free surface, the sweep, dihedral and anhedral angles on the lift and drag coefficients are discussed for swept and V-type WIGs.

scholarly journals Four free surface algorithms for the 3D Navier–Stokes equations

2015 ◽  
Vol 17 (6) ◽  
pp. 845-856 ◽  
Author(s):  
Nils Reidar B. Olsen
Keyword(s):  
Wave Equation ◽  
Numerical Methods ◽  
Water Surface ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Free Water ◽  
Navier Stokes ◽  
Time Step ◽  
Navier Stokes Equations ◽  
Free Water Surface

Four algorithms are described for computing a steady free water surface with the solution of the three-dimensional (3D) Navier–Stokes equations. The numerical methods are used in hydraulic engineering cases, typically spillways and river modelling. The algorithms were tested against a laboratory experiment of a v-shaped broad-crested weir. The complex geometry of the weir introduced three-dimensional effects, which the numerical methods handled with varying degrees of success. One of the methods tested was the classical volume of fluid (VOF) approach, implemented in the OpenFOAM software with a fixed grid. The other three algorithms used an adaptive grid that followed the free water surface. These methods were coded in the SSIIM 2 program and were based on water continuity, pressure differences and an implicit solution of the diffusive wave equation. The VOF method gave the best results compared with the experiments. However, this method requires a very short time step. Two of the investigated methods compute the water surface location implicitly and can therefore use a much longer time step. The method based on the diffusive wave equation has the disadvantage that the results depend on a calibrated friction factor. All four methods predicted the water depth over the weir with an average accuracy below 14%.

scholarly journals Three-Dimensional Numerical Method for Simulating Large-Scale Free Water Surface by Massive Parallel Computing on a GPU

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2121 ◽  
Author(s):  
Yongqin Peng ◽  
Wei Diao ◽  
Xujin Zhang ◽  
Chunze Zhang ◽  
Shuqing Yang
Keyword(s):  
Parallel Computing ◽  
Water Surface ◽  
Large Scale ◽  
Three Dimensional ◽  
Free Water ◽  
Dam Break ◽  
Evolution Process ◽  
Engineering Practice ◽  
Scale Free ◽  
Free Water Surface

Water wave dynamics and its engineering application have always been a key issue in the field of hydraulics, and effective and efficient numerical methods need to be proposed to perform three-dimensional (3-D) simulation of large-scale water fluctuation in engineering practice. A single-phase free-surface lattice Boltzmann method (SPFS-LB method) is coupled with a large-eddy simulation approach for simulating large-scale free water surface flows, and the simulation is accelerated on a GPU (graphic processing unit). The coupling model is used to simulate the evolution process of dam-break wave after complete and partial dam-break. The formation mechanism of horizontal and vertical vortices in water after partial dam-break and the advance and evolution process of dam-break flow on non-contour riverbed are analyzed. The method has been verified to be reasonable and can obtain a more accurate time curve of water level fluctuation. Applying this method to practical arch dams, discharge coefficients consistent with empirical formulas can be obtained by comparison and analysis, and the surface flow phenomena (such as tongue diffusion, surface fragmentation, and surface fusion) can be well simulated by this method. In addition, based on the key technology of parallel computing on a GPU, the implementation of the SPFS-LB model on a GPU unit achieves tens of millions of lattice updates per second, which is over fifty times higher than that on a single CPU chip. It is proved that the proposed method for large-scale water fluctuations can be used to study practical engineering problems. The mathematical model method realizes the efficient and accurate simulation of practical physical problems.

Using computer vision to monitor varying water levels: an exploratory laboratory experience

2021 ◽  
Author(s):  
Jorge Isidoro ◽  
Ricardo Martins ◽  
João de Lima
Keyword(s):  
Computer Vision ◽  
Free Surface ◽  
Water Surface ◽  
Free Water ◽  
Water Levels ◽  
High Temporal Resolution ◽  
Piping System ◽  
Measuring Device ◽  
Spatial And Temporal Scales ◽  
Free Water Surface

<p>Monitoring water levels is fundamental in a variety of fields within geosciences, hydraulics, and hydrology. Examples of this can be found in the field in rivers, reservoirs, or surface runoff while, at a much lower scale, in the laboratory, e.g., open channel flow. This is an area of ​​great complexity, due to the large diversity of spatial and temporal scales of hydraulic systems and phenomena such as the non-linearity of fluid mechanics, sediment or pollutant transport, turbulence, the interactions between water and solid surfaces (natural or artificial), or atmospheric boundary conditions. The last decade has brought important advances in techniques associated with the acquisition and analysis of images, techniques encompassed in what is currently called “computer vision”.</p><p>In this work, a methodology based on image treatment and segmentation techniques was developed, which allows the detection of the free flow water surface over time in laboratory conditions using simple video equipment.</p><p>The objective of this work was to develop and validate an algorithm for detecting the free water surface with high temporal resolution. Other specific objectives were: (i) to validate the algorithm against measurements in a steady-state flow; (ii) to test the algorithm for accentuated oscillations of the free surface resulting from different bed geometries, slope, and discharge; and (iii) to assert the feasibility of the systematic use of non-specialized and inexpensive video equipment as a level measuring device, without compromising its accuracy.</p><p>All laboratory work took place at the Laboratory of Hydraulics, Water Resources and Environment of the Department of Civil Engineering of the Faculty of Sciences and Technology of the University of Coimbra. The channel has dimensions of 4.00m × 0.15m (L×W) and the slope is adjustable. Water is supplied to the channel, in a closed circuit, from a reservoir by means of a pump and piping system, and the flow controlled by a ball valve. The algorithm developed for detecting the free surface is based on the acquisition, treatment, analysis, and segmentation of images. MATLAB® was used to code functions to recognize the edges present in an image by the image intensity gradient as well as the best-defined segment present in the image, which, in this case, corresponds to the free water surface.</p>

EFEKTIVITAS TANAMAN GENJER DALAM MENURUNKAN BOD DAN COD LIMBAH CAIR TAHU HASIL PROSES ANAEROB

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Muhammad Irvan Nurliansyah
Keyword(s):  
Water Surface ◽  
Free Water ◽  
Surface Flow ◽  
Free Water Surface

ABSTRAK Limbah cair tahu merupakan limbah cair yang berasal dari proses pembuatan tahu. Limbah cair tahu mengandung senyawa organik yang tinggi. Pembuangan limbah cair tahu secara langsung ke badan air tanpa dilakukan pengolahan dapat mempengaruhi dan mencemari lingkungan. Suatu cara untuk menanggulangi permasalahan tersebut adalah melakukan pengolahan limbah cair tahu. Salah satu alternatif pengolahan limbah cair tahu yang dapat digunakan adalah fitoremediasi menggunakan tanaman genjer. Penelitian ini bertujuan untuk mengetahui efisiensi pengolahan dan efektivitas waktu tinggal pengolahan limbah cair tahu menggunakan tanaman genjer dalam menurunkan BOD dan COD effluen hasil proses pengolahan anaerob limbah cair tahu. Metode yang digunakan dalam penelitian ini adalah fitoremediasi menggunakan tanaman genjer pada sistem lahan basah buatan Free Water Surface flow dengan waktu tinggal 3 hari, 5 hari dan 7 hari. Hasil penelitian menunjukkan bahwa efisiensi pengolahan secara fitoremediasi pada hari ke 3 untuk BOD dan COD berturut-turut sebesar 21,28% dan 16,13%. Pada hari ke 5 efisiensi pengolahan yang diperoleh untuk BOD dan COD berturut-turut sebesar 52,60% dan 45,93% sedangkan efisiensi pengolahan pada hari ke 7 untuk BOD dan COD berturut-turut sebesar 76,42% dan 70,74%. Waktu tinggal efektif yang diperoleh pada penelitian ini adalah  7 hari dengan nilai BOD dan COD telah berada dibawah baku mutu yaitu berturut-turut sebesar 72,72 mg/l dan 213,33 mg/l.   Kata kunci : limbah cair tahu, fitoremediasi, tanaman genjer, efisiensi pengolahan, waktu tinggal

A Free Water Surface Constructed Wetland in Treating Sugarcane Wastewater

2011 ◽  
Vol 33 (1) ◽  
pp. 71-86
Author(s):  
Doorce S. Batubara ◽  
Donald Dean Adrian
Keyword(s):  
Constructed Wetland ◽  
Water Surface ◽  
Free Water ◽  
Free Water Surface
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