computational fluid dynamics Articles
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Managing CFD simulation: reflections around a questionnaire
The topic is Computational Fluid Dynamics (CFD) as a simulation tool within the engineering design process. The engineering design process is considered as a problem-solving process and its focus is on the role of simulation. "Simulation" is defined and a distinction between simulation and analysis is made. Based on a theoretical model of the CFD simulation process and the results from ...
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Irreversibilities reduction of a flow distribution system by means of the EGM methodology
The present work reports the results of an entropy generation analysis on a symmetric flow distributor. The entropy generation minimisation method (EGM) was applied in order to lower the intrinsic irreversibilities associated to the geometric configuration of the flow pattern, aiming to improve the uniformity of flow distribution. 3D Computational Fluid Dynamics (CFD) methods were used to ...
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Investigation of four geometrical parameters on thermal stratification of cold water tanks by exergy analysis
In this paper, effects of four geometrical parameters of tanks on the thermal stratification within a cold storage tank are analysed. Nine two–dimensional models have been numerically simulated by using the Computational Fluid Dynamics (CFD) program, fluent. Realistic boundary and initial conditions are applied. The level of thermal stratification in each model has been quantified by means of ...
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Second law analysis of a gravity–driven liquid film flowing along an inclined plate subjected to constant wall temperature
The second law analysis of a gravity–driven liquid having temperature–dependent viscosity and flowing along an inclined heated plate was studied. The computational fluid dynamics (CFD) package FLUENT was used to obtain the velocity and temperature gradients, and the results were used to determine the entropy generation rate. Different cases of inclination angle and dimensionless parameters were ...
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Application of Computational Fluid Dynamics to flow next to high-rise buildings in Hong Kong due to air-conditioner heat rejection
This paper presents the results of several studies done for high-rise residential buildings in Hong Kong that involved Computational Fluid Dynamics (CFD) simulation. During summer, a number of Window Air-Conditioners (WACs) could be rejecting condenser heat into a recessed space of these high-rise residential buildings. FLUENT 5.0, a CFD code can be used to predict temperatures and flow field of ...
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Modelling of atmospheric flow and dispersion in the wake of a cylindrical obstacle
The computational fluid dynamics code ADREA–HF is used to simulate atmospheric dispersion field experiments around an isolated cylindrical obstacle and two upwind sources of ammonia and propane, with the ammonia source located at different lateral positions. Model calculated concentrations and concentration fluctuations are compared with the experimental results, to investigate the effect of the ...
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Investigation of the performance of single and multi–drop hydraulic structures
In this paper, the work is divided into two parts. First, the hydraulic performance of single and multi–drop structures is investigated and compared using two approaches. In the first approach, the empirical equations found in the literature are summarised and reanalysed to compare the dissipation of energy of single drop and multi–drop structures. The demarcation condition at which multi–drop ...
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Irreversibilities reduction of a flow distribution system by means of the EGM methodology
The present work reports the results of an entropy generation analysis on a symmetric flow distributor. The entropy generation minimisation method (EGM) was applied in order to lower the intrinsic irreversibilities associated to the geometric configuration of the flow pattern, aiming to improve the uniformity of flow distribution. 3D Computational Fluid Dynamics (CFD) methods were used to ...
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Dispersion of pollutants in a street canyon and street intersection under traffic-induced flow and turbulence using a low Re κ-ε model
A 3-D Eulerian-Lagrangian approach to moving vehicles is presented that takes into account the traffic-induced flow rate and turbulence. The method is applied to pollutant dispersion in an individual street canyon and a system of two street canyons forming a perpendicular intersection. The approach is based on computational fluid dynamics (CFD) calculations using a Eulerian approach for ...
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Two- and three-phase simulations of an ill-functioning dissolved-air flotation tank
Computational Fluid Dynamics (CFD) simulations were employed to examine the performance of a large-scale Dissolved-Air Flotation (DAF) tank. The tank was ill-functioning as it was operated with bubbles larger than designed for. Different multiphase models, turbulence models and boundary conditions for the free surface of the tank were tested in 2D simulations. The simulation results were assessed ...
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Performance measurement of a twisted three-bladed airfoil-shaped H-rotor
In the present study, performance of a twisted three-bladed airfoilshaped H-rotor was measured experimentally for different values of chord Reynolds number of flow and ratios of height-to-diameter (H/D). The rotor was 20 cm in height (H) and 5 cm in chord with about 26° twist at the trailing end. Tests were conducted in an open circuit subsonic wind tunnel for ten H/D ratios, namely 0.85, ...
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Enhancement of ejector performance for a desalination system
This paper describes the use of Computational Fluid Dynamics (CFD) to investigate the performance of the ejector used in desalination applications that use air as the working fluid. A three-dimensional model for the CFD was used to investigate the effect of operating conditions and ejector geometry on ejector performance. The results show that ejector performance increases by increasing the ...
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Modelling of pressure drop in eccentric narrow horizontal annuli with the presence of cuttings and rotating drillpipe
Accurate pressure drop estimation is vital in wellbore hydraulic design. The present study investigates the effects of diameter ratio, fluid velocity, fluid type, fluid rheology and drillpipe rotation speed on pressure drop in eccentric horizontal wellbore with the presence of cuttings using computational fluid dynamics (CFD). The drillpipe is positioned at eccentricity of 0.623 and rotates about ...
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Computational modeling of ultraviolet disinfection
The efficient design of ultraviolet light (UV) systems for water and wastewater treatment requires detailed knowledge of the patterns of fluid motion that occur in the disinfection channel. This knowledge is increasingly being obtained using Computational Fluid Dynamics (CFD) software packages that solve the equations governing turbulent fluid-flow motion. In this work, we present predictions of ...
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Towards optimal design parameters for around-the-end hydraulic flocculators
ABSTRACTHydraulic flocculators are principally characterized by their volume (which determines the time of flocculation) and the water level difference between inlet and outlet (which determines the average energy dissipation).Within these constraints, however, the designer has many degrees of freedom, such as the average water depth, the number and spacing of baffles, the length of the gap at ...
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A new formula based on computational fluid dynamics for estimating maximum depth of scour by jets from overflow dams
The prediction of the maximum depth of the scour hole formed downstream of overflow dams is critical in determining the safety of hydraulic structures. Most of the conventional formulae are not able to consider complex hydraulic and morphologic conditions. A new formula for estimating the maximum depth of the scour hole based on computational fluid dynamics (CFD), which can be used to simulate ...
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The computation of the entropy generation rate for turbomachinery design applications: some theoretical remarks and practical examples
The calculation of the entropy generation rate dS/dt in turbomachinery passages is a relatively easy task, once the velocity and temperature fields are known in detail. The global entropy generation rate is directly related to the cascade efficiency, but its functional dependence on the local characteristics of the flowfield is not immediately detectable. On the contrary, knowledge of the local ...
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CFD modelling of sampling locations for early detection of spontaneous combustion in long–wall gob areas
In this study, computational fluid dynamics (CFD) modelling was conducted to optimise gas sampling locations for the early detection of spontaneous heating in longwall gob areas. Initial simulations were carried out to predict carbon monoxide (CO) concentrations at various regulators in the gob using a bleeder ventilation system. Measured CO concentration values at these regulators were then used ...
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An experimental investigation and optimisation of flat plate heat sink
This study is focused on multiple response optimisation of a flat plate heat sink using grey relational analysis and Taguchi design of experiments. The responses considered are electromagnetic emitted radiation and thermal resistance of the heat sink. The emitted radiation and thermal resistance of the heat sink were obtained using Ansoft HFSS and Flotherm CFD simulation, respectively. The ...
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Smoke Movement in a Compartmental Fire
Transport of larger smoke particles generated by a fire in a compartment is studied. An atrium fire with three different heat release rates is taken as an example. The air flow pattern and temperature contours are predicted by a fire field (or application of computational fluid dynamics (CFD) model. The paths of smoke particles are modeled by the Lagrangian method coupled with the air movement ...
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