Application of a three dimensional model for the prediction of pollutant dispersion in Cyprus coastal waters

1995 ◽  
Vol 32 (9-10) ◽  
pp. 179-187 ◽  
Author(s):  
I. P. Glekas
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Pollutant Dispersion ◽  
Plume Dispersion ◽  
Three Dimensional Model ◽  
Tracer Injection ◽  
Coastal System ◽  
Sea Bed

A recently developed numerical model for environmental flows has been applied to simulate the water circulation and pollutant dispersion in a confined coastal system in Cyprus. The model is based on the numerical solution of the time averaged Navier-Stokes equations, written in their contravariant strong conservation form, in a generalised non-orthogonal coordinate system. The model predictions are verified compared with experimental data incorporating radioactive tracer injection at the surface of the sea, then the model is applied to predict the dispersion of waste from the outfall pipe of a sewage treatment plant. The predicted results agree favourably with the measurements, demonstrating the code's validity, flexibility and economy for predicting accurately flows in three-dimensional complex sea bed terrain basins. The utilisation of such a model can be an advantageous alternative to the expensive and time consuming experimental field work, enabling the study of the plume dispersion under different discharge and hydrological prevailing conditions.

Numerical and Experimental Analysis of 3D Micro-Corrugated Wing in Gliding Flight

2021 ◽  
Author(s):  
Nasim Chitsaz ◽  
Kamran Siddiqui ◽  
Romeo Marian ◽  
Javaan S. Chahl
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Three Dimensional Model ◽  
Wing Model ◽  
Computational Fluid Dynamics Analysis ◽  
Gliding Flight ◽  
Flat Profile

Abstract In this study, computational fluid dynamics analysis was performed on a three-dimensional model of a Libellulidae wing to determine aerodynamic performance in gliding flight. The wing is comprised of various corrugated features alongside the spanwise and chordwise directions, as well as twist. The detailed features of real 3D dragonfly wing models, including all the corrugations through both span and chord, have not been considered in the past for a detailed aerodynamic analysis. The simulations were conducted by solving the Navier-Stokes equations to demonstrate gliding performance over a range of angles of attack at low Reynolds numbers. The numerical model was validated against experimental data obtained from a fabricated corrugated wing model using particle image velocimetry. The numerical results demonstrate that bio-inspired wings with corrugations compared to flat profile wings generate more lift with lower drag, trapping the vortices in the valleys of wing corrugation leading to delayed flow separation and delayed stall. The experimental and numerical results demonstrate that the methodology presented in this study can be used to measure bio-inspired 3D wing flow characteristics, including the influence of complex corrugations on aerodynamic performance. These findings contribute to the advancement of knowledge required for designing an optimized bioinspired micro air vehicle.

scholarly journals AERODYNAMICS OF JETS INTERACTING WITH A FLAT SURFACE

2019 ◽  
Vol 62 (4) ◽  
pp. 263-269
Author(s):  
I. A. Pribytkov ◽  
S. I. Kondrashenko
Keyword(s):  
Heat Transfer ◽  
Critical Point ◽  
Flat Surface ◽  
Stokes Equations ◽  
Thermal State ◽  
Exchange Process ◽  
Three Dimensional ◽  
Internal Diameter ◽  
Three Dimensional Model ◽  
Aerodynamic Properties

In this paper, the development features of a single free jet of hightemperature nitrogen interacting with a flat surface were studied. Calculation of the heat exchange process during heating by the attacking jets is very difficult to implement analytically due to complexity of the gas-dynamic processes occurring both in a single jet and in a system of jets interacting with the metal. The computational difficulties are aggravated by the fact that when interacting with the surface the jet as such disappears. The flat (fan) flow interacts with the surface: form, aerodynamic properties and thermal state of the flow strongly differ from those of the original jet. The studies were conducted on the basis of numerical simulation in the FloEFD software and computing complex for multiphysical simulation based on solution of the equations of gas dynamics and heat transfer. The solved system of equations consisted of Navier-Stokes equations, equations of energy and continuity and was supplemented by k – ε turbulence model. A three-dimensional model was developed for simulation, the necessary properties, initial and boundary conditions were specified. In the study of aerodynamics of a single high-temperature jet interacting with the surface, the main defining values were: nitrogen flow rate from the nozzle U0 , nitrogen temperature T, internal diameter of the nozzle d0 , distance from the nozzle section to the surface h, distance from the critical point (point of intersection of the jet axis with the surface) along the flow radius r. Data on the gas velocity decrease as the jet develops due to the loss of initial energy to engage the motionless surrounding gas in motion, is presented. The studies have shown that increase in the initial velocity of gas outflow brings the area of higher velocities closer to the surface both in the jet itself and in the fan jet. This factor contributes to heat transfer intensification. In addition, high speeds increase the total thickness of the fan flow and reduce the thickness of hydrodynamic boundary layer, which increases with distance from the critical point.

scholarly journals Hydrodynamic Effects Produced by Submerged Breakwaters in a Coastal Area with a Curvilinear Shoreline

2019 ◽  
Vol 7 (10) ◽  
pp. 337 ◽  
Author(s):  
Francesco Gallerano ◽  
Giovanni Cannata ◽  
Federica Palleschi
Keyword(s):  
Coastal Area ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Integral Form ◽  
Navier Stokes ◽  
Hydrodynamic Effect ◽  
Riemann Solver ◽  
Three Dimensional Model ◽  
Navier Stokes Equations

A three-dimensional numerical study of the hydrodynamic effect produced by a system of submerged breakwaters in a coastal area with a curvilinear shoreline is proposed. The three-dimensional model is based on an integral contravariant formulation of the Navier-Stokes equations in a time-dependent curvilinear coordinate system. The integral form of the contravariant Navier-Stokes equations is numerically integrated by a finite-volume shock-capturing scheme which uses Monotonic Upwind Scheme for Conservation Laws Total Variation Diminishing (MUSCL-TVD) reconstructions and an Harten Lax van Leer Riemann solver (HLL Riemann solver). The numerical model is used to verify whether the presence of a submerged coastal defence structure, in the coastal area with a curvilinear shoreline, is able to modify the wave induced circulation pattern and the hydrodynamic conditions from erosive to accretive.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

2011 ◽  
Vol 55-57 ◽  
pp. 343-347 ◽  
Author(s):  
Yi Gang Luan ◽  
Hai Ou Sun
Keyword(s):  
Pressure Drop ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Model ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Resistance Performance

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

CHANGES IN WATER QUALITY AND FISHERY PRODUCTION IN JINHAE BAY

2017 ◽  
Author(s):  
Kyunghoi Kim ◽  
Kyunghoi Kim ◽  
Oh Seok Jin ◽  
Oh Seok Jin ◽  
In-Cheol Lee ◽  
...  
Keyword(s):  
Water Quality ◽  
Red Tide ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Intertidal Flat ◽  
Sea Bed ◽  
Fish Catch ◽  
Jinhae Bay

For the better understanding of long-term variations of water quality in Jinhae Bay after establishment of special law, we analyzed the archive data monitored in Jinhae Bay during the last 17 years (1997-2013). And change on fish catch due to the variations of water quality was investigated. A marked decrease in the number of red tide occurrence is due to the effectiveness of the law and sewage treatment plant that has targeted the reduction of COD in the effluent water since early 2000. Although the improvement of water quality, increase in fishery production was not observed in Jinhae Bay. For the recovery of fishery production, processes for restoration of entire ecosystem such as restoration of artificial intertidal flat and seaweed bed and remediation of organic-rich sea bed should be accompanied with improvement of water quality.

Three-Dimensional Computational Hydrodynamics Modeling for Algae Transport and Growth

2017 ◽  
Author(s):  
Haidong Liu ◽  
Zhongquan Charlie Zheng ◽  
Bryan Young
Keyword(s):  
Green Algae ◽  
Hydrodynamic Model ◽  
Algal Blooms ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Fractional Step Method ◽  
Blue Green Algae

In this study, a three-dimensional model coupling hydrodynamics with algae transport dynamics is investigated. The hydrodynamic model solves the three-dimensional Navier-Stokes equations by a semi-implicit, fractional step method, where the hydrostatic components are determined first and the non-hydrostatic pressure and other components are determined in a subsequent step. Wind velocity on the water surface is accounted for the effect of wind stress on the flow velocities in the hydrodynamic model. Then, the model is coupled with an algae transport model, which enables simulation of algae transport and algal blooms. As an example, the model is implemented to analyze the transition of blue-green algae in Milford Lake, which is the largest man-made lake in Kansas suffering from blue-green algae blooms. The three-dimensional model provides a robust and efficient way for hydrodynamic and algae modeling and can be implemented to studies on different types of rivers and reservoirs easily. The simulated results can be very useful for algae control and prediction in both short and long terms.

Numerical Simulation Analysis on the Flow Mechanism of Passive Containment Cooling System

2013 ◽  
Author(s):  
Yang Song ◽  
Wei-Hua Li ◽  
Sheng-Qiang Li
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Simulation Analysis ◽  
Cooling System ◽  
Early Stage ◽  
Three Dimensional ◽  
Cooling Water ◽  
Navier Stokes ◽  
Flow Mechanism ◽  
Three Dimensional Model

In the third generation PWR, passive containment cooling system was one of the key security parts. If accident happened, the blasting valves in the containment would automatically open and the steam would be injected into the containment. When the pressure reached a certain value, the tank on the top of containment would automatically spray. Driven by gravity, the cooling water would flow along outer surface of containment. Steam inside the containment would condense on inner wall and the pressure in the containment would decrease. A numerical simulation of steam jet in the passive containment cooling system was carried out using computational fluid dynamics methods. Flow mechanism in the process was studied. A simplified three-dimensional model of the passive containment cooling system was built. The hexahedral structured mesh was made. The RNG k-epsilon turbulence model was used in solving the transient Reynolds Navier-Stokes equations by the Fluent. The distributions of velocity in containment at different time were acquired. Reference would be provided for understanding of flow mechanism of gas jet-flow in containment during the early stage of accident.

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