The Prediction of Surface Discharge Jets by a Three-Dimensional Finite-Difference Model

1980 ◽  
Vol 102 (1) ◽  
pp. 138-145 ◽  
Author(s):  
G. D. Raithby ◽  
G. E. Schneider
Keyword(s):  
Finite Difference ◽  
Three Dimensional ◽  
Design Tool ◽  
Surface Discharge ◽  
Three Dimensional Model ◽  
Finite Difference Solution ◽  
Surface Discharges ◽  
Semi Empirical ◽  
Heated Jet ◽  
Good Agreement

A three-dimensional model is presented which describes the thermal and hydrodynamic behavior of a turbulent heated jet entering at the surface of a receiving body of water. A two-equation turbulence model, together with a semi-empirical description of the preferential attenuation of vertical turbulent exchange due to buoyancy, is used to predict non-isotropic turbulent diffusivities. A finite-difference solution method, involving several novel features, has been used. Predictions are compared with both field and laboratory measurements, for both deep and shallow receiving basins, for the special case of a quiescent ambient fluid. Good agreement is found, indicating that the model can be reliably used as a design tool, or to evaluate the environmental impact of surface discharges.

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

A System of Selective Non Catalytic Reduction of NOx for Diesel Engine

2011 ◽  
Vol 201-203 ◽  
pp. 643-646 ◽  
Author(s):  
Bo Yan Xu ◽  
Hai Ying Tian ◽  
Jie Yang ◽  
De Zhi Sun ◽  
Shao Li Cai
Keyword(s):  
Catalytic Reduction ◽  
Three Dimensional ◽  
Exhaust Gas ◽  
Test Results ◽  
Practical Application ◽  
Three Dimensional Model ◽  
Reduction Efficiency ◽  
Different Temperatures ◽  
Reduction Of Nox ◽  
Good Agreement

SNCR (Selective Non Catalytic Reduction) system is proposed, with 40% methylamine aqueous solution as reducing agent to reduce NOx in diesel exhaust gas. The effect of injection position and volume on the reduction efficiency through the test bench is systematically researched. A three-dimensional model of a full-sized diesel SNCR system generated by CFD software FIRE is used to investigate the reduction efficiency under different temperatures. The simulated results have a good agreement with the test results, and it can be used to optimize SNCR system. The results can indicate the practical application of this technology.

Numerical Investigation on Unstable Oscillations of Two Circular Cylinders in Tandem Arrangement

2003 ◽  
Author(s):  
Yoshiaki Itoh ◽  
Ryutaro Himeno
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Numerical Investigation ◽  
Difference Method ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Damping Force ◽  
Negative Damping ◽  
Good Agreement ◽  
Three Dimensional Simulations

Three-dimensional simulations of incompressible and viscous flow around tandem circular cylinders at Re = 20000 in unstable oscillations can be carried out by means of finite difference method without any turbulence model. The numerical response behaviors are in good agreement with the previous experimental ones. The mechanism of negative damping force in vortex-induced oscillations and wake-galloping is investigated.

Three‐dimensional induction logging problems, Part 2: A finite‐difference solution

Geophysics ◽  
2002 ◽  
Vol 67 (2) ◽  
pp. 484-491 ◽  
Author(s):  
Gregory A. Newman ◽  
David L. Alumbaugh
Keyword(s):  
Finite Difference ◽  
Electric Field ◽  
Krylov Subspace ◽  
Inverse Operator ◽  
Three Dimensional ◽  
Staggered Grid ◽  
Linear System Of Equations ◽  
Order Of Magnitude ◽  
Finite Difference Solution ◽  
Difference Solution

A 3‐D finite‐difference solution is implemented for simulating induction log responses in the quasi‐static limit that include the wellbore and bedding that exhibits transverse anisotropy. The finite‐difference code uses a staggered grid to approximate a vector equation for the electric field. The resulting linear system of equations is solved to a predetermined error level using iterative Krylov subspace methods. To accelerate the solution at low induction numbers (LINs), a new preconditioner is developed. This new preconditioner splits the electric field into curl‐free and divergence‐free projections, which allows for the construction of an approximate inverse operator. Test examples show up to an order of magnitude increase in speed compared to a simple Jacobi preconditioner. Comparisons with analytical and mode matching solutions demonstrate the accuracy of the algorithm.

Waves of Acoustically Induced Transparency in Bubbly Liquids: Theoretical Prediction and Experimental Validation

2013 ◽  
Author(s):  
Nail A. Gumerov ◽  
Iskander S. Akhatov ◽  
Claus-Dieter Ohl ◽  
Sergei P. Sametov ◽  
Maxim V. Khasimulin ◽  
...  
Keyword(s):  
Acoustic Field ◽  
Acoustic Waves ◽  
Three Dimensional ◽  
Self Organization ◽  
Nonlinear Phenomenon ◽  
Three Dimensional Model ◽  
Bubbly Liquids ◽  
Strongly Nonlinear ◽  
Induced Transparency ◽  
Good Agreement

Self-organization of bubbles in acoustic fields, or self-action of the acoustic waves in bubbly liquids is a strongly nonlinear phenomenon due to two-way interaction of the bubbles and the acoustic field. Theoretical model and preliminary computations predict that waves of self-induced acoustic transparency may exist. Such effect is confirmed in the experiments presented in this paper. Formation of a wave of void fraction which rapidly propagates through the bubbly medium leaving a region almost free of bubbles behind its front is observed in the experiments. Measurements of the dynamics of such a wave at different acoustic frequencies and amplitudes are carried out. A three dimensional model of self-organization of a polydisperse bubble continuum in acoustic field is developed and the results of simulations are compared with experiments. A good agreement of the theory and experiment is found.

A three-dimensional model of the human airway tree

1999 ◽  
Vol 87 (6) ◽  
pp. 2207-2217 ◽  
Author(s):  
Hiroko Kitaoka ◽  
Ryuji Takaki ◽  
Béla Suki
Keyword(s):  
3D Model ◽  
Human Lung ◽  
Three Dimensional ◽  
Deterministic Algorithm ◽  
Three Dimensional Model ◽  
Fluid Delivery ◽  
Human Airway ◽  
Airway Tree ◽  
Function Relationship ◽  
Good Agreement

A three-dimensional (3D) model of the human airway tree is proposed using a deterministic algorithm that can generate a branching duct system in an organ. The algorithm is based on two principles: 1) the amount of fluid delivery through a branch is proportional to the volume of the region it supplies; and 2) the terminal branches are arranged homogeneously within the organ. These principles define the basic process of branching: generation of the dimensions and directionality of two daughter branches is governed by the properties of the parent branch and the region the parent supplies. The algorithm is composed of nine basic rules and four complementary rules. When the contour of an organ and the position of the trunk are specified, branches are successively generated by the algorithm. Applied to the human lung, the algorithm generates an airway tree that consists of ∼54,000 branches. Its morphometric characteristics are in good agreement with those reported in the literature. The algorithm and the 3D airway model are useful for studying the structure-function relationship in the lung.

scholarly journals Near-Field Diffraction from a Binary Microaxicon

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Victor V. Kotlyar ◽  
Sergey S. Stafeev ◽  
Roman V. Skidanov ◽  
Victor A. Soifer
Keyword(s):  
Finite Difference ◽  
Focal Spot ◽  
Optical Axis ◽  
Near Field ◽  
Three Dimensional ◽  
Finite Difference Schemes ◽  
Cylindrical Coordinates ◽  
Linearly Polarized ◽  
Experimental Values ◽  
Good Agreement

We study binary axicons of period 4, 6, and 8 μm fabricated by photolithography with a 1 μm resolution, 500 nm depth, and 4 mm diameter. Near-field diffraction focal spots varying in diameter from 3.5λ to 4.5λ (for the axicon of period T=4 μm) and from 5λ to 8λ (for the axicon with T=8 μm) are experimentally found on the optical axis at a distance of up to 40 μm from the axicon for the wavelength λ=0.532 μm. The first focal spot is found at distance 2 μm (T=4 μm), with the period of the focal spots being 2 μm (T=4 μm) and 4 μm (T=8 μm). Diffraction of linearly polarized plane and diverging waves is simulated using FullWAVE (RSoft) and a proprietary program BOR-FDTD, which implement finite-difference schemes to solve three-dimensional Maxwell's equations in the Cartesian and cylindrical coordinates. The numerically simulated values for diameters of the near-field focal spots for the axicon of period T=4 μm are in good agreement with the experimental values.

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