Evaluation of Various Turbulence Models in Predicting Airflow and Turbulence around a Generic Vehicle Model

2014 ◽  
Vol 989-994 ◽  
pp. 3468-3472 ◽  
Author(s):  
Cheng Wu ◽  
Yi Ping Wang ◽  
Xue Yang
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Turbulence Models ◽  
Separation Flow ◽  
Rans Turbulence Models ◽  
Aerodynamic Drag Coefficient ◽  
Selection Of

For vehicle external aerodynamic computation, the selection of the turbulence model is very important. In current research, ten RANS turbulence models were introduced to compute the time-averaged flow field around the Ahmed model with 25° backlight angle. In order to evaluate the feasibility of the turbulence model, the results were compared with the related published experimental data. The results showed that the two equations RANS turbulence models were more favorable to compute the vehicle external flow field, but parts of the two equations turbulence model just could predict the aerodynamic drag coefficient or lift coefficient effectively. However, the results further revealed that the realizable k-ε could obtain the more accurate drag coefficient and lift coefficient simultaneously, and simulate the complex separation flow in the wake.

Application of Response Surface Model on Aerodynamic Characteristic of Airfoil

2014 ◽  
Vol 610 ◽  
pp. 70-73
Author(s):  
Cheng Long Liu ◽  
Hui Zhu ◽  
Zhi Gang Yang
Keyword(s):  
Response Surface ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Response Surface Model ◽  
Surface Model ◽  
Aerodynamic Drag Coefficient ◽  
Sample Points ◽  
Computational Resources ◽  
Development And Validation ◽  
Selection Of

To reduce the computational resources, experimental design and response surface method (RSM) were employed to investigate the aerodynamic drag coefficient (CD) and lift coefficient (CL) of airfoils by using CFD methods. The selection of sample points, development and validation of response surface model and the effects of different sample points on approximation model were discussed. The results indicates that the number and distribution of sample points have a significant impact on model accuracy and optimize results. Also this method can greatly reduce calculation amount.

Aerodynamic Analysis of a Vehicle Tanker

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ramon Miralbes Buil ◽  
Luis Castejon Herrer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Positive Impact ◽  
Aerodynamic Resistance ◽  
Independent Contribution ◽  
Aerodynamic Drag Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Selection Of

The aim of this article is the presentation of a series of aerodynamic improvements for semitrailer tankers, which reduce the aerodynamic resistance of these vehicles, and, consequently, result in a positive impact on fuel consumption, which is substantially reduced (up to 11%). To make the analysis the computational fluid dynamics (CFD) methodology, using FLUENT, has been used since it allows simulating some geometries and modifications of the geometry without making physical prototypes that considerably increase the time and the economical resources needed. Three improvements are studied: the aerodynamic front, the undercarriage skirt, and the final box adaptor. First they are studied in isolation, so that the independent contribution of each improvement can be appreciated, while helping in the selection of the most convenient one. With the aerodynamic front the drag coefficient has a reduction of 6.13%, with the underskirt 9.6%, and with the boat tail 7.72%. Finally, all the improvements are jointly examined, resulting in a decrease of up to 23% in aerodynamic drag coefficient.

Aerodynamic Drag Reduction of SUV Based on Underbody Cover Board

2014 ◽  
Vol 602-605 ◽  
pp. 477-480
Author(s):  
Jing Yu Wang ◽  
Bao Yu Wang ◽  
Xing Jun Hu ◽  
Lei Liao
Keyword(s):  
Flow Field ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Flow Line ◽  
Wind Tunnel Test ◽  
Aerodynamic Performance ◽  
Simulation Based ◽  
Aerodynamic Drag Coefficient ◽  
Aerodynamic Drag Reduction

The principles and method of computational fluid dynamics were applied to numerical simulate the external flow field about the SUV model. The hybrid mesh of tetrahedral and triangular prismatic as well as the turbulence model of Realizable k-ε was adopted to study the flow field of SUV of flat underground. Then the SUV of complex underground was simulated with the same mesh strategy and boundary condition. The aerodynamic drag coefficient of latter was bigger than former. That illuminated the complex underground has affect to aerodynamic performance of vehicle. The wind tunnel test validated the veracity of numerical simulation. Based on that, the underground cover board was appended; the aerodynamic drag coefficient was depressed. The velocity and pressure distribution and flow line were achieved. The conclusions provide theoretical reference for the further study of aerodynamic drag reduction of complex underground.

scholarly journals Experimental Determination of the Impact of Floats on the Aerodynamic Characteristics of an OSA Model in Symmetric Flow

2021 ◽  
Vol 12 (1) ◽  
pp. 41-58
Author(s):  
Michał FRANT ◽  
Stanisław WRZESIEŃ ◽  
Maciej MAJCHER
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Symmetric Flow ◽  
Aerodynamic Drag Coefficient ◽  
The Impact ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper presents the results of experimental determination of the impact of floats on the aerodynamic characteristics of an OSA model in symmetric flow. The studies have been performed in the low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland). The aircraft model was examined at the dynamic pressure q = 500 Pa in the following angle of attack range = -2828. The investigations have been performed for an aircraft model under plain configuration with floats and without floats. The influence of elevator and flap inclination on the aerodynamic characteristics of the model has also been analysed. The obtained values of aerodynamic drag coefficient, lift coefficient, pitching moment coefficient and lift-to-drag ratio have been presented in the form of tables and graphs. The studies performed demonstrated that the use of floats causes the increase of aerodynamic drag coefficient CD, maximum lift coefficient CLmax as well as critical angle of attack cr. The decrease of lift-to-drag ratio has also been observed. Its value in the case of the model with floats was up to 20% lower than in the model without floats. The studies also showed that the model equipped with floats had a lower longitudinal static stability margin than the model without floats.

Two-Dimensional Study of the Turbulent Wake Behind a Square Cylinder Subject to Uniform Shear

2000 ◽  
Author(s):  
A. K. Saha ◽  
G. Biswas ◽  
K. Muralidhar
Keyword(s):  
Drag Coefficient ◽  
Strouhal Number ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Turbulence Models ◽  
Direct Calculation ◽  
Square Cylinder ◽  
Shear Parameter ◽  
High Reynolds ◽  
Direct Calculations

Abstract The flow past a square cylinder at a high Reynolds number has been simulated through direct calculations and through the calculations using turbulence models. The present investigation highlights significant differences between the two approaches in terms of instantaneous flow, Strouhal number and the aerodynamic forces. The time-averaged drag coefficient and the rms fluctuations due to the direct calculation are higher than those due to the turbulence model. However, Strouhal number is underpredicted in direct calculations. The effect of shear on the flow has also been determined using the turbulence model. The time-averaged drag coefficient is found to decrease with the increase in shear parameter up to a certain value. Then it increases with the further increase in the shear parameter. On the other hand, the lift coefficient increases with the increase in shear parameter. Strouhal number shows a decreasing trend with the increase in shear parameter whereas the rms values of the drag and lift coefficients increase with the shear parameter. Kármán Vortex Street, mainly comprising of clockwise vortices due to shear, decays slowly compared to uniform flow condition.

Application of RNG k-ε Turbulence Model on Numerical Simulation in Vehicle External Flow Field

2012 ◽  
Vol 170-173 ◽  
pp. 3324-3328 ◽  
Author(s):  
Jing Yu Wang ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Turbulence Model ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Car Model ◽  
Drag And Lift

The two turbulence models were used to numerically simulate the external flow field around the Ahmed standard car model, and the aerodynamic drag and lift coefficients and aerodynamic characteristics around model were obtained. By comparison between the simulation results and the corresponding wind tunnel test data, the differences of two turbulence models were analyzed. The results indicated the simulation result of RNG k-εturbulence model is more precision, and it is more suitable on numerical simulation in vehicle external flow field. The conclusions provide reference for how to select turbulence model.

Numerical Simulation of Sand Erosion Phenomena in Square-Section 90 Degree Bend With Linear/Nonlinear RANS Turbulence Models

2007 ◽  
Author(s):  
Masaya Suzuki ◽  
Kazuaki Inaba ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Turbulence Models ◽  
Solid Particles ◽  
Two Phase ◽  
Streamline Curvature ◽  
Sand Erosion ◽  
Rans Turbulence Models ◽  
Wall Deformation ◽  
Bend Flow

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with among others. On the other hand, the sand erosion is a serious problem to install pneumatic conveying systems for handling abrasive materials. Incidentally, the bend erosion is typical target of sand erosion experiments and is useful for verification of numerical simulations. Although, the secondary flow which occurs in such a flow field including streamline curvature cannot be reproduced by the standard k-ε model. To predict this flow field, a more universal model which can estimate anisotropic Reynolds stress is required. In the present study, we simulate sand erosion of 90 degree bend with a square cross-section. We use some linear/nonlinear turbulence models to predict the secondary flow of the bend. Besides, the performance of each model to predict clear/eroded bend flow field is studied.

Sign in / Sign up

Export Citation Format

Share Document