scholarly journals Comparison of CFD Simulation to UAS Measurements for Wind Flows in Complex Terrain: Application to the WINSENT Test Site

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1992 ◽  
Author(s):  
Asmae El Bahlouli ◽  
Alexander Rautenberg ◽  
Martin Schön ◽  
Kjell zum Berge ◽  
Jens Bange ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cfd Simulation ◽  
Test Site ◽  
Unmanned Aircraft ◽  
Navier Stokes ◽  
Area Index ◽  
Flow Features ◽  
High Turbulence ◽  
Computational Fluid Dynamics Cfd ◽  
Aircraft System

This investigation presents a modelling strategy for wind-energy studies in complex terrains using computational fluid dynamics (CFD). A model, based on an unsteady Reynolds Averaged Navier-Stokes (URANS) approach with a modified version of the standard k-ε model, is applied. A validation study based on the Leipzig experiment shows the ability of the model to simulate atmospheric boundary layer characteristics such as the Coriolis force and shallow boundary layer. By combining the results of the model and a design of experiments (DoE) method, we could determine the degree to which the slope, the leaf area index, and the forest height of an escarpment have an effect on the horizontal velocity, the flow inclination angle, and the turbulent kinetic energy at critical positions. The DoE study shows that the primary contributor at a turbine-relevant height is the slope of the escarpment. In the second step, the method is extended to the WINSENT test site. The model is compared with measurements from an unmanned aircraft system (UAS). We show the potential of the methodology and the satisfactory results of our model in depicting some interesting flow features. The results indicate that the wakes with high turbulence levels downstream of the escarpment are likely to impact the rotor blade of future wind turbines.

CFD Simulation of Propeller and Tunnel Thruster Performance

2014 ◽  
Author(s):  
Ping Lu ◽  
Sue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Open Water ◽  
Ship Hull ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Computational Domain ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift

In the present study, the hydrodynamic performance of a typical North Sea dynamic positioning (DP) shuttle tanker consisting of two main propellers, two rudders, and two bow tunnel thrusters is investigated by solving Reynolds-averaged Navier-Stokes (RANS) equations for a viscous flow. The focus of the numerical simulation is on the performance of propellers/rudders and bow tunnel thrusters considering the hydrodynamic interactions between propellers/thrusters, hull and current. The numerical model includes hull, propeller, rudder, bow tunnel thruster and flow field. First, an analysis of a propeller performance in open water is carried out by calculating the coefficient of thrust, torque, and propeller efficiency. Then, rudders are included in the analysis for the assessment of propeller/rudder performance. The pressure distribution on rudders, rudder’s drag and lift coefficients for different angles of attack, and flow field around the rudder are obtained. The interaction effects between propeller, rudder, ship hull, as well as bow tunnel thruster and ship hull are analyzed by adding detailed ship hull geometry in the computational domain. The tunnel thruster efficiency reduction due to current and ventilation is also analyzed. The presence of current leads to significant changes in the flow velocity and distribution of pressure in the tunnel outflow area as well as significant deflection of the propeller jet emitting from the tunnel. A comparison between Computational Fluid Dynamics (CFD) and model test results of flow features near the tunnel area with various current speeds is presented.

scholarly journals VERIFICATION OF SCHRENK METHOD FOR WING LOADING ANALYSIS OF SMALL UNMANNED AIRCRAFT USING NAVIERSTOKES BASED CFD SIMULATION

2018 ◽  
Vol 15 (2) ◽  
pp. 161 ◽  
Author(s):  
Arifin Rasyadi Soemaryanto ◽  
Nurhayyan Halim Rosid
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Approximation Method ◽  
Cfd Simulation ◽  
Unmanned Aircraft ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Wing Loading ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Prediction of an aerodynamic load acting on a wing or usually called wing loading becomes an important stage for structural analysis. Several methods have been used in estimating the wing loading. Schrenk approximation method is commonly used to achieve the fast estimation of lift distribution along wingspan, but in order to achieve a high level accuracy of aerodynamic prediction, computational fluid dynamics (CFD) with Navier Stokes-based equation can be used. LAPAN Surveillance UAV (LSU series) has been chosen to represent an aerodynamics analysis on generic small unmanned aircraft with twinboom vertical stabilizer configuration. This study was focused to verify the Schrenk approximation method using high accuracy numerical simulation (CFD). The goal of this study was to determine the lift distribution along wingspan and a number of errors between Schrenk approximation and CFD method. In this study, Schrenk approximation result showed similarity with the CFX simulation. So the two results have been verified in analysis of wing loading. ABSTRAKPrediksi dari beban aerodinamika yang terjadi pada sayap menjadi salah satu tahap yang penting dalam analisis struktur perancangan pesawat. Beberapa metode telah digunakan untuk mengestimasi besarnya beban aerodinamika pada sayap. Metode Schrenk umum digunakan untuk estimasi cepat perhitungan besar distribusi gaya angkat di sepanjang sayap. Guna mencapai tingkat akurasi yang tinggi dari prediksi aerodinamika, simulasi Computational Fluid Dynamics (CFD) dengan berbasis persamaan Navier-Stokes dapat digunakan. Pesawat nirawak LSU dipilih untuk merepresentasikan analisis aerodinamika pada pesawat nirawak dengan konfigurasi twin-tailboom pusher. Fokus dari studi yang dilakukan adalah untuk memverifikasi dari metode pendekatan dari Schrenk dengan menggunakan metode yang memiliki akurasi tinggi seperti simulasi CFD. Tujuan dari studi adalah untuk menghitung distribusi gaya angkat sepanjang sayap dan menentukan seberapa besar error dari kedua metode.

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.

Turbine Airfoil Heat Transfer Predictions Using CFD

2005 ◽  
Author(s):  
Anil K. Tolpadi ◽  
James A. Tallman ◽  
Lamyaa El-Gabry
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Design System ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Airfoils ◽  
Typical Design

Conventional heat transfer design methods for turbine airfoils use 2-D boundary layer codes (BLC) combined with empiricism. While such methods may be applicable in the mid span of an airfoil, they would not be very accurate near the end-walls and airfoil tip where the flow is very three-dimensional (3-D) and complex. In order to obtain accurate heat transfer predictions along the entire span of a turbine airfoil, 3-D computational fluid dynamics (CFD) must be used. This paper describes the development of a CFD based design system to make heat transfer predictions. A 3-D, compressible, Reynolds-averaged Navier-Stokes CFD solver with k-ω turbulence modeling was used. A wall integration approach was used for boundary layer prediction. First, the numerical approach was validated against a series of fundamental airfoil cases with available data. The comparisons were very favorable. Subsequently, it was applied to a real engine airfoil at typical design conditions. A discussion of the features of the airfoil heat transfer distribution is included.

CFD Simulation of Curved-Roof Subjected to Thunderstorm Downburst

2011 ◽  
Vol 474-476 ◽  
pp. 1243-1248
Author(s):  
Bi Qi Cui ◽  
Yong Chen
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Cfd Simulation ◽  
Wind Pressure ◽  
Windward Side ◽  
Strong Wind ◽  
Pressure Distributions ◽  
The World ◽  
Computational Fluid Dynamics Cfd ◽  
Structural Failures

Thunderstorm downburst is a sort of outburst strong wind on or near the ground, and its wind field characteristics are significantly different from boundary layer winds. The study on its effect on the structures was relatively rare, nevertheless numerous structural failures around the world caused by thunderstorm were found. Computational fluid dynamics (CFD) was employed for this stationary downburst simulation, also the wind pressure distributions of the curved-roof in this flow had been surveyed by varying the parameters of the structure. The results show that the wind attack angle has significant effect on the wind pressure of curved-roof, so does the ratio of the rise to span. The predominant impacts of the ratio of wall height to span and the roof span were found at the windward side. Furthermore, by locating the roof beneath the downburst jet, the wind pressure distribution of the roof was also investigated to reveal the significant effects caused by vertical wind of downburst.

scholarly journals The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

2019 ◽  
Author(s):  
Pál Schmitt ◽  
Christian Windt ◽  
Josh Davidson ◽  
John V. Ringwood ◽  
Trevor Whittaker
Keyword(s):  
Shallow Water ◽  
Source Function ◽  
Cfd Simulation ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Wide Range ◽  
Rans Models ◽  
Hydrodynamic Processes ◽  
Computational Fluid Dynamics Cfd ◽  
Shallow Water Models

Computational Fluid Dynamics (CFD) simulations, based on Reynolds Averaged Navier Stokes (RANS) models, are a useful tool for a wide range of coastal and offshore applications, providing a high fidelity representation of the underlying hydrodynamic processes. Generating input waves in the CFD simulation is performed by a numerical wavemaker (NWM), with a variety of different NWM methods existing for this task. While NWMs, based on impulse source methods, have been widely applied for wave generation in depth averaged, shallow water models, they have not seen the same level of adoption in the more general RANS based CFD simulations, due to difficulties in relating the required impulse source function to the resulting free surface elevation for non-shallow water cases. This paper presents an implementation of an impulse source wavemaker, which is able to self-calibrate the impulse source function to produce a desired wave series in deep or shallow water at a specific point in time and space. Example applications are presented, for a numerical wave tank (NWT), based on the opensource CFD software OpenFOAM, for wave packets in deep and shallow water, highlighting the correct calibration of phase and amplitude. Also, the suitability for cases requiring very low reflection from NWT boundaries is demonstrated. Possible issues in the use of the method are discussed and guidance for good application is given.

scholarly journals Validating CFD Predictions of Flow over an Escarpment Using Ground-Based and Airborne Measurement Devices

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4688 ◽  
Author(s):  
Asmae El Bahlouli ◽  
Daniel Leukauf ◽  
Andreas Platis ◽  
Kjell zum Berge ◽  
Jens Bange ◽  
...  
Keyword(s):  
Mesoscale Model ◽  
Potential Temperature ◽  
Test Site ◽  
Unmanned Aircraft ◽  
Horizontal Wind ◽  
Cfd Validation ◽  
Wind Speeds ◽  
Inclination Angles ◽  
Aircraft System ◽  
Calm Wind

Micrometeorological observations from a tower, an eddy-covariance (EC) station and an unmanned aircraft system (UAS) at the WINSENT test-site are used to validate a computational fluid dynamics (CFD) model, driven by a mesoscale model. The observation site is characterised by a forested escarpment in a complex terrain. A two-day measurement campaign with a flow almost perpendicular to the escarpment is analysed. The first day is dominated by high wind speeds, while, on the second one, calm wind conditions are present. Despite some minor differences, the flow structure, analysed in terms of horizontal wind speeds, wind direction and inclination angles shows similarities for both days. A real-time strategy is used for the CFD validation with the UAS measurement, where the model follows spatially and temporally the aircraft. This strategy has proved to be successful. Stability indices such as the potential temperature and the bulk Richardson number are calculated to diagnose atmospheric boundary layer (ABL) characteristics up to the highest flight level. The calculated bulk Richardson values indicate a dynamically unstable region behind the escarpment and near the ground for both days. At higher altitudes, the ABL is returning to a near neutral state. The same characteristics are found in the model but only for the first day. The second day, where shear instabilities are more dominant, is not well simulated. UAS proves its great value for sensing the flow over complex terrains at high altitudes and we demonstrate the usefulness of UAS for validating and improving models.

scholarly journals Pressure Coefficients Acting Upon the Cylinder Obtained by Numerical and Experimental Analysis

2017 ◽  
Vol 13 (2) ◽  
pp. 149-155
Author(s):  
Soňa Medvecká ◽  
Oľga Ivánková ◽  
Marek Macák
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Cross Section ◽  
Cfd Simulation ◽  
Circular Cross Section ◽  
Wind Pressure ◽  
Wind Flow ◽  
Pressure Coefficients ◽  
High Rise ◽  
Computational Fluid Dynamics Cfd

Abstract Analysis of wind flow acting upon high-rise buildings is a very common topic. This paper deals with experiment in the Boundary Layer Wind Tunnel (BWLT) in Bratislava and comparison with the computational fluid dynamics (CFD) simulation and values given in the Eurocode. The analyzed object was the model of building with circular cross section (cylinder). External wind pressure coefficients were compared in three height levels of model.

scholarly journals Nanofluid Flow Past a Stretching Plate

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 827
Author(s):  
Gabriella Bognár ◽  
Mohamad Klazly ◽  
Krisztián Hriczó
Keyword(s):  
Boundary Layer ◽  
Nusselt Number ◽  
Skin Friction ◽  
Cfd Simulation ◽  
Skin Friction Coefficient ◽  
Boundary Layer Theory ◽  
Nanofluid Flow ◽  
Magnetite Fe3o4 ◽  
Computational Fluid Dynamics Cfd ◽  
Stretching Plate

Viscous nanofluid flow due to a sheet moving with constant speed in an otherwise quiescent medium is studied for three types of nanofluids, such as alumina (Al2O3), titania (TiO2), and magnetite (Fe3O4), in a base fluid of water. The heat and mass transfer characteristics are investigated theoretically using the boundary layer theory and numerically with computational fluid dynamics (CFD) simulation. The velocity, temperature, skin friction coefficient, and local Nusselt number are determined. The obtained results are in good agreement with known results from the literature. It is found that the obtained results for skin friction and for the Nusselt number are slightly greater than those obtained via boundary layer theory.

Sign in / Sign up

Export Citation Format

Share Document