Meta-Modeling Based Optimization of a Directional Augmentation Technique on Improving the Performance of Six Blades Savonius Rotor Using CFD Analysis

2016 ◽  
Author(s):  
Mst Sunzida Ferdoues ◽  
Krishna Vijayaraghavan
Keyword(s):  
Wind Velocity ◽  
Optimization Procedure ◽  
Navier Stokes ◽  
Surface Model ◽  
Navier Stokes Equation ◽  
Convergent Nozzle ◽  
Savonius Rotor ◽  
Meta Modeling ◽  
Computational Fluid Dynamics Cfd ◽  
The Moment

The performance of Savonius wind turbine can be improved by increasing the effective wind velocity. One of the methods of improving the effective wind velocity is using directional augmentation technique, which actually affects the Omnidirectional capability of the Savonius rotor. This paper works on this method by using convergent nozzle at the outlet of the rotor. The whole work is based on Metamodeling based optimization and numerical simulation. Reynolds averaged Navier-stokes equation (RANS) based turbulence model has been used for simulations, such as static simulation and dynamic simulation. The CFD simulations are validated against previously published experimental data. The optimization procedure is performed by integrating the Design of Experiment (DOE), Computational Fluid Dynamics (CFD), Response Surface Model (RSM) and analysis of variance (ANOVA). The meta-model is able to identify significant design variable and the interactions. The proposed optimal nozzle is shown to improve the coefficient of the moment from 0.3 to 0.44.

A Verification and Validation Study of CFD Simulation of Wind-Induced Ventilation on Building with Single-Sided Opening

2014 ◽  
Vol 554 ◽  
pp. 696-700 ◽  
Author(s):  
Nur Farhana Mohamad Kasim ◽  
Sheikh Ahmad Zaki ◽  
Mohamed Sukri Mat Ali ◽  
Ahmad Faiz Mohammad ◽  
Azli Abd Razak
Keyword(s):  
Open Source Software ◽  
Natural Ventilation ◽  
Cfd Simulation ◽  
Previous Experiment ◽  
Experimental Methods ◽  
Verification And Validation ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Computational Fluid Dynamics Cfd ◽  
Model Approach

Wind-induced ventilation is widely acknowledged as one of the best approaches for inducing natural ventilation. Computational fluid dynamics (CFD) technique is gaining popularity among researchers as an alternative for experimental methods to investigate the behavior of wind-driven ventilation in building. In this present paper, Reynolds averaged Navier-Stokes equation (RANS) k-ε model approach is considered to simulate the airflow on a simplified cubic building with an opening on a single façade. Preliminary simulation using models from previous experiment indicates the reliability of OpenFOAM, the open source software that will be used in this study. The results obtained in this study will better define options for our future study which aims to explore how different buildings arrays modify the airflow inside and around a naturally ventilated building.

OPEN SOURCE COMPUTATIONS OF PLANING HULL RESISTANCE

2015 ◽  
Vol 157 (B2) ◽  
Author(s):  
M Ferrando ◽  
S Gaggero ◽  
D Villa
Keyword(s):  
Open Source ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Navier Stokes Equation ◽  
Free Surfaces ◽  
Hydrodynamic Parameters ◽  
Physical Problems ◽  
Engineering Problems ◽  
Simulation Strategy ◽  
Computational Fluid Dynamics Cfd

In recent years, the application of Computational Fluid Dynamics (CFD) methods experienced an exponential growth: the increase of the computational performances and the generalization of the Navier-Stokes equation to more complex physical problems made possible the solution of complex problems like free surfaces flows. The physical complexity of planing hulls flows poses some issues in the ability to numerically predict the global hydrodynamic parameters (hull resistance, dynamic attitude) of these configurations and on the expected confidence on the numerical results. In the last decade, commercial RANS software have been successfully applied for the prediction of the planing hull characteristics with reasonable correlation to the available experimental measurements. Recently, moreover, the interest in Open Source approaches, also for the solution of engineering problems, has rapidly grow. In this work, a set of calculations on a systematic series standard hull shape has been carried out, adopting from pre- to post- processing only Open Source tools. The comparison and the validation, through the available experimental measurements, of the computed results will define an optimal simulation strategy to include this kind of tools in the usual design loop.

Prediction of Particle Impact on an Archimedes Screw Runner Blade for Micro Hydro Turbine

2013 ◽  
Vol 465-466 ◽  
pp. 552-556
Author(s):  
Muhammad Ammar Nik Mutasim ◽  
Nurul Suraya Azahari ◽  
Ahmad Alif Ahmad Adam
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Particle Impact ◽  
Three Dimensional Flow ◽  
Navier Stokes Equation ◽  
Runner Blade ◽  
Computational Fluid Dynamics Cfd ◽  
The Subject ◽  
The Impact

Energy is one of the most important sources in the world especially for developing countries. The subject study is conducted to predict the behaviour of particle due to errosion from the river through the achimedes screw runner and predict the impact of particle toward blade surface. For this reason, computational fluid dynamics (CFD) methods are used. The three-dimensional flow of fluid is numerically analyzed using the Navier-Stokes equation with standard k-ε turbulence model. The reinverse design of archimedes screw blade was refered with the previous researcher. Flow prediction with numerical results such as velocity streamlines, flow pattern and pressure contour for flow of water entering the blade are discussed. This study shows that the prediction of particle impact occurs mostly on the entering surface blade and along the leading edge of the screw runner. Any modification on the design of the screw runner blade can be analyze for further study.

Pumping Speed Measurement of the Rotary Vane Vacuum Pump by Using Numerical and Experimental Approaches

2014 ◽  
Author(s):  
M. Nadeem Azam ◽  
M. Umar ◽  
M. Maqsood ◽  
Imran Akhtar ◽  
Imran Aziz
Keyword(s):  
Internal Flow ◽  
Vacuum Pump ◽  
Assessment System ◽  
Navier Stokes ◽  
Vane Pump ◽  
Navier Stokes Equation ◽  
Time Shape ◽  
Experimental Approaches ◽  
Computational Fluid Dynamics Cfd ◽  
The One

Pumping speed is the main performance parameter of a vacuum pump. In the present work, pumping speed for a three-vane rotary vacuum pump is quantified using both experimental and numerical approaches. The numerical methodology assumes continuum flow (Knudsen number < 0.1), thus allowing the use of Navier Stokes equation. Commercial computational fluid dynamics (CFD) solver i.e. Fluent, is used to discretize the governing equations. Moving / dynamic mesh technique is used for the internal flow volumes of the pump to reproduce the change-in-time shape. Complete process starting from the CAD modeling to CFD simulations is discussed in detail. The adopted approaches are generic and can be used to find the pumping speed of any other rotary vane vacuum pump. The vane pump is also tested using an assessment system, which is constructed according to DIN28432 standard. Results of experimentally measured pumping speed are in good agreement with the one computed numerically.

RELAXATION METHOD FOR NAVIER–STOKES EQUATION

2012 ◽  
Vol 23 (04) ◽  
pp. 1250021 ◽  
Author(s):  
P. M. C. DE OLIVEIRA
Keyword(s):  
Steady State ◽  
Stokes Equation ◽  
Wind Velocity ◽  
Linear Time ◽  
Navier Stokes ◽  
Cylinder Surface ◽  
Theoretical Problem ◽  
Navier Stokes Equation ◽  
Transient Time ◽  
Ball Speed

The motivation for this work was a simple experiment [P. M. C. de Oliveira, S. Moss de Oliveira, F. A. Pereira and J. C. Sartorelli, preprint (2010), arXiv:1005.4086], where a little polystyrene ball is released falling in air. The interesting observation is a speed breaking. After an initial nearly linear time-dependence, the ball speed reaches a maximum value. After this, the speed finally decreases until its final, limit value. The provided explanation is related to the so-called von Kármán street of vortices successively formed behind the falling ball. After completely formed, the whole street extends for some hundred diameters. However, before a certain transient time needed to reach this steady-state, the street is shorter and the drag force is relatively reduced. Thus, at the beginning of the fall, a small and light ball may reach a speed superior to the sustainable steady-state value. Besides the real experiment, the numerical simulation of a related theoretical problem is also performed. A cylinder (instead of a 3D ball, thus reducing the effective dimension to 2) is positioned at rest inside a wind tunnel initially switched off. Suddenly, at t = 0 it is switched on with a constant and uniform wind velocity [Formula: see text] far from the cylinder and perpendicular to it. This is the first boundary condition. The second is the cylinder surface, where the wind velocity is null. In between these two boundaries, the velocity field is determined by solving the Navier–Stokes equation, as a function of time. For that, the initial condition is taken as the known Stokes laminar limit V → 0, since initially the tunnel is switched off. The numerical method adopted in this task is the object of the current text.

scholarly journals Velocity Control of Visco-Elastic Materials Movement in the Cylindrical Channel of the Grinder Feed Screw of the Former

2019 ◽  
Vol 49 (1) ◽  
pp. 113-119
Author(s):  
Екатерина Фоменко ◽  
Ekaterina Fomenko ◽  
Альберт Нугманов ◽  
Albert Nugmanov
Keyword(s):  
Raw Material ◽  
Navier Stokes ◽  
Surface Model ◽  
Automation System ◽  
Additional Time ◽  
Adhesive Properties ◽  
Navier Stokes Equation ◽  
Feed Screw ◽  
Pass Through ◽  
The One

The present research features the problems of wheat processing. Wheat processing has its own specific features. For instance, the process of gluten extrusion forming is very complex since it is associated with the visco-elastic and adhesive properties of raw gluten. The article discusses the results of applying the numerical finite difference method to the Navier-Stokes equation in the case of the one-dimensional problem when a cooled viscoelastic material has to pass through circular nozzles. The paper also features the obtained surface model of velocity evolution and some averaged results for the possible automation of the process. The viscosity properties of raw gluten are variable and depend on temperature, chemical composition, and properties of the raw material. Modeling makes it possible to characterize the properties of the material and its behavior in various situations. Such research demands neither additional time nor significant costs. The authors identified patterns of movement for raw gluten in the extrusion molding unit and selected the most appropriate automation system to control the speed of its movement to the molding assembly in the grinder feed screw. The significance of the research is obvious for subsequent physical and mathematical modeling of heat and mass transfer processes of vacuum freezing and drying and granulating of gluten extrusions. The results of the research presented in the article are consistent with the available information on this topic. The present approach to solving the problem of choosing the best rational hydrodynamic regimes was applied due to the complexity of the experimental determination of velocity fields and the difficulty of analyzing the Navier-Stokes system of hydrodynamic differential equations with variable proportionality coefficients.

On the Effective Viscosity Expression for Modeling Squeeze-Film Damping at Low Pressure

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Maria F. Pantano ◽  
Leonardo Pagnotta ◽  
Salvatore Nigro
Keyword(s):  
Experimental Data ◽  
Stokes Equation ◽  
Effective Viscosity ◽  
Optimization Procedure ◽  
Low Pressure ◽  
Squeeze Film ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Navier Stokes Equation ◽  
Squeeze Film Damping

While at high pressure, the classical Navier–Stokes equation is suitable for modeling squeeze-film damping, at low pressure, it needs some modification in order to consider fluid rarefaction. According to a common approach, fluid rarefaction can be included in this equation by substituting the standard fluid viscosity with a fictitious quantity, known as effective viscosity, for which different formulations were proposed. In order to identify which expression works better, the results obtained when either formulation is implemented inside the Navier–Stokes equation (that is then solved by both analytical and numerical means) are compared with already available experimental data. At the end, a novel expression is discussed, derived from a computer-assessed optimization procedure.

scholarly journals What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review

2019 ◽  
Vol 40 (5) ◽  
pp. 1021-1039 ◽  
Author(s):  
Khalid M Saqr ◽  
Sherif Rashad ◽  
Simon Tupin ◽  
Kuniyasu Niizuma ◽  
Tamer Hassan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Intracranial Aneurysms ◽  
Meta Analysis ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Fundamental Properties ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd ◽  
Supplementary Material

Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier–Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.

scholarly journals STATORS USE INFLUENCE ON THE PERFORMANCE OF A SAVONIUS WIND ROTOR USING COMPUTATIONAL FLUID DYNAMICS

2011 ◽  
Vol 10 (1-2) ◽  
pp. 63
Author(s):  
J. V. Akwa ◽  
A. P. Petry
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Cylindrical Shape ◽  
Tip Speed Ratio ◽  
Eddy Viscosity Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Moment ◽  
Volume Method

This paper aims at verifying the influence of using five kinds of stators in the averaged moment and power coefficients of a Savonius wind rotor using computational fluid dynamics (CFD). The analyzed stators have cylindrical shape with two and three openings, one and four deflector blades and walls shaped like a wings. The equations of continuity, Reynolds Averaged Navier-Stokes – RANS and the Eddy Viscosity Model k-ω SST, in its Low-Reynolds approaches, with hybrid near wall treatment; are numerically solved using the commercial software Star-CCM+, based on Finite Volume Method, resulting in the fields of pressure and velocity of the flow and the forces acting on the rotor buckets. The moment and power coefficients are achieved through integration of forces coming from the effects of pressure and viscosity of the wind on the buckets device. The influence of the stators use in the moment and power coefficients is checked by changing the geometry of the device for each simulations series, keeping the Reynolds number based on rotor diameter equal to 433,500. The obtained values for averaged moment and power coefficients indicate that for each type of stator used, there was maximum performance for a given tip speed ratio of rotor. Improvement in performance over the operation without stator was obtained only to the operations using stator with four deflector blades and to the stator with cylindrical shape with three openings. The improvement percentage in performance obtained for the best condition (use of four deflector blades at tip speed ratio equal to 1) is 12% compared to the performance of the rotor operating without stator.

scholarly journals Validation and Verification of CFD Prediction of Fluid Flow of a Submerged Vertical Round Jet

2018 ◽  
Vol 3 (2) ◽  
pp. 113-121
Author(s):  
Nurul Hasan ◽  
Ahmed Oliur Rahman ◽  
Md. Shah Alam
Keyword(s):  
Symmetric Domain ◽  
Navier Stokes ◽  
Computational Error ◽  
Navier Stokes Equation ◽  
Validation And Verification ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method ◽  
Grid Independence ◽  
Better Than

This paper presents a step by step verification and validation process of a vertical round submerged jet into a cylindrical bath. Taking advantage of the axi-symmetric domain, Navier-Stokes equation of primary is solved by finite volume method (FVM) using commercial computational fluid dynamics, CFD (Fluent) software. For verification and to minimise the computational error, step by step grid independence tests were performed. For validation, experimental data was produced using laser Doppler velocimetry (LDV). Among the turbulence model,  SST was found to predict the flow behaviour better than k-e-  realization or RSM models. 

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