Numerical and Neural Study of the Turbulent Flow Around Sharp-Edged Bodies

2002 ◽  
Author(s):  
Ahmed F. Abdel Gawad
Keyword(s):  
Flow Field ◽  
Thermal Behavior ◽  
Turbulence Modeling ◽  
Unstructured Grids ◽  
Flow Direction ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Pressure Distributions ◽  
Special Concern ◽  
Artificial Neural Network Ann

The study is based on K-ε turbulence modeling using both structured and unstructured grids. The pressure distributions in the flow field and on the surfaces of the bodies are determined. Different parameters that affect the flow field such as Reynolds number, aspect ratio of the body, and flow direction are considered. Special concern is paid to the separations at the corners of the body and the circulations behind the body. The thermal behavior due to the flow field is also considered. Nusselt number on the heated surfaces of the body is examined. The thermal behavior of a given body is strongly dependent on its aerodynamic characteristics. Comparisons are made between the present results and the available experimental data. Artificial Neural Network (ANN) was used to predict the values of the drag coefficient. Many useful conclusions and suggestions were drawn from the study.

scholarly journals CFD Analysis of the Influence of the Front Wing Setup on a Time Attack Sports Car’s Aerodynamics

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7907
Author(s):  
Maciej Szudarek ◽  
Janusz Piechna
Keyword(s):  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
Vital Role ◽  
Front Axle ◽  
The Body ◽  
Strong Interactions ◽  
Unexpected Result ◽  
Proper Position ◽  
Pressure Distributions ◽  
Front Wing

In time attack races, aerodynamics plays a vital role in achieving short track times. These races are characterized by frequent braking and acceleration supported by aerodynamic downforce. Usually, typical cars are modified for these races by amateurs. Adjusting the aerodynamic solutions to work with bodies developed for other flow conditions is difficult. This paper presents the results of a numerical analysis of the effects of installing a straight wing in front of or above the body on the modified vehicle system’s aerodynamic characteristics, particularly on the front wheels’ aerodynamic downforce values. The paper presents the methodology and results of calculations of the aerodynamic characteristics of a car with an additional wing placed in various positions in relation to the body. The numerical results are presented (Cd, Cl, Cm, Clf, Clr), as well as exemplary pressure distributions, pathlines, and visualizations of vortex structures. Strong interactions between the wing operation and body streamline structure are shown. An interesting and unexpected result of the analysis is that the possibility of obtaining aerodynamic downforce of the front wheels is identified, without an increase in aerodynamic drag, by means of a wing placed in a proper position in front of the body. A successful attempt to balance the additional downforce coming from the front wing on the front axle is made using a larger spoiler. However, for large angles of attack, periodically unsteady flow is captured with frequency oscillations of ca. 6–12 Hz at a car speed of 40 m/s, which may interfere with the sports car’s natural suspension frequency.

Simulation Research on Aerodynamic Characteristics of Vehicle under Steady Crosswind Based on XFlow

2014 ◽  
Vol 494-495 ◽  
pp. 138-141
Author(s):  
Shan Ling Han ◽  
Zhi Yong Li ◽  
Jin Bin Li ◽  
Ru Xing Yu
Keyword(s):  
Flow Field ◽  
Surface Pressure ◽  
Body Surface ◽  
Crucial Role ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Wake Flow ◽  
Aerodynamic Coefficient ◽  
Simulation Research ◽  
The Asymmetry

The aerodynamic characteristics of vehicle play a crucial role in steering stability, comfort and safety of vehicle. The crosswind will affect the aerodynamic characteristics of vehicle. In this paper, the aerodynamic characteristics of ASMO model under steady crosswind is simulated by XFlow software, and the changes of aerodynamic characteristics under different steady crosswind are analyzed. It turned out that the asymmetry of wake flow field is enhanced with the increasing of crosswind, and the body surface pressure of windward is amplified, the six components of aerodynamic coefficient are also increased. It is found that the vehicle aerodynamic characteristics changed obviously under steady crosswind.

CFD-BASED SELF-PROPULSION SIMULATION FOR FROG SWIMMING

2014 ◽  
Vol 14 (06) ◽  
pp. 1440012 ◽  
Author(s):  
JIZHUANG FAN ◽  
WEI ZHANG ◽  
YANHE ZHU ◽  
JIE ZHAO
Keyword(s):  
Flow Field ◽  
Large Range ◽  
Hydrodynamic Forces ◽  
The Body ◽  
Joint Motion ◽  
Mechanism Analysis ◽  
Hydrodynamic Problem ◽  
Pressure Distributions ◽  
Body Velocity ◽  
Computational Fluid Dynamics Cfd

Mechanism analysis of frog swimming is an interesting subject in the field of biofluid mechanics and bionics. Computing the hydrodynamic forces acting on a frog is difficult due to its characteristics of explosive propulsion and large range of joint motion. To analyze the flow around the body and vortices in the wake, in this paper, the method based on Computational Fluid Dynamics (CFD) was utilized to solve the velocity and pressure distributions in the flow field and on the frog. The hydrodynamic problem during the propulsive phase of a frog, Xenopus laevis, was calculated using the CFD software FLUENT. A self-propulsion simulation was performed which computed the body velocity from the joint trajectory input and CFD solved the hydrodynamic forces, and visual CFD results of the hydrodynamic forces and flow field structures were obtained.

Simulation of Flow-Induced Oscillations of a Rectangular Bluff Body in Incompressible, Turbulent Flow

2002 ◽  
Author(s):  
Ulf Bunge ◽  
Andreas Gurr ◽  
Frank Thiele
Keyword(s):  
Bluff Body ◽  
Turbulence Modeling ◽  
Flow Direction ◽  
Oscillatory Behavior ◽  
The Body ◽  
Navier Stokes ◽  
Mean Flow ◽  
Time Step ◽  
Numeric Simulation ◽  
Linear Spring

The incompressible flow around a rectangular body with a length to height ratio of L/H = 2 and its flow–induced oscillatory behavior is numerically investigated at different Re–numbers in a range between 1 to 6 · 104. The body has one degree of freedom perpendicular to the mean–flow direction with a linear spring and linear damping. To compute the flow a finite–volume based Navier–Stokes CFD-code is used, which is enhanced by a finite–difference based algorithm to solve the vibration differential equation. Target is the numeric simulation of a incident flow velocity where resonance occurs and the exact determination of the physical mechanisms especially in the flowing medium. Particular substantial parameters of the total model, e.g. turbulence modeling, time step or grid, which exert influence on the quality of the simulation are examined. To achieve this aim simulations with steady and oscillating body are compared with experimental data and deviations are analyzed.

Simulation of Interference Characteristics of the Model Supporting Beams with Different Forms of Section in Wind Tunnel Test

2014 ◽  
Vol 1025-1026 ◽  
pp. 910-913
Author(s):  
Xing Jun Hu ◽  
Yue Xing Miao
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Three Dimensional Flow ◽  
Ansys Fluent ◽  
Correction Error ◽  
Dimensional Flow ◽  
Pressure Distributions

In order to study the effects of the supporting beams with different forms of section on the aerodynamic characteristics of car models. Model supporting beams with three different forms of section were designed based on standard MIRA model. The commercial CFD software - Ansys Fluent was used to simulate the three-dimensional flow field around the standard MIRA model installed with three different kinds of supporting beams. With comparisons between the drag coefficients, pressure distributions and velocity distributions around the wheels with the different supporting beams, the reasons for the differences in aerodynamics are analyzed and advices were given for helping choosing the supporting beam with minimal disturbance to reduce the correction error.

scholarly journals Aerodynamic Characteristics of Isolated Loaded Tires with Different Tread Patterns: Experiment and Simulation

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Haichao Zhou ◽  
Zhen Jiang ◽  
Guolin Wang ◽  
Shupei Zhang
Keyword(s):  
Flow Field ◽  
Aerodynamic Drag ◽  
Flow Direction ◽  
Air Flow ◽  
Flow Characteristics ◽  
Aerodynamic Characteristics ◽  
Test Model ◽  
Pressure Coefficients ◽  
Pressure Area ◽  
The Impact

AbstractThe current research of tire aerodynamics mainly focus on the isolated and simplified tread tire. Compared with the real complex pattern tire, the tread pattern structure and deformed profile of a loaded tire has a greatly influence on tire aerodynamic drag. However, the mechanisms of the isolated loaded tires with different tread patterns effects on the aerodynamic drag are subjects worthy of discussion. The purpose of this study is to experimentally and computationally investigate the aerodynamic characteristics of three tires 185/65 R14 with different patterns under loaded. A wind tunnel test model was first established using three-dimensional (3D) printing with a ratio of 1:1, and the pressure coefficients Cp of the three tires with different patterns are measured. The paper then conducted computational fluid dynamics (CFD) simulations for analyzing the pressure and flow characteristics. The accuracy of CFD simulation is verified by comparing the simulation results with the test results of pressure coefficients Cp, and they are of good consistency. While, the general analysis of pressure coefficients Cp results of the three tires indicates high-pressure area on the windward surface, and occurrence of low-pressure area on the leeward surface, the pressure coefficients Cp of all three tires decreased firstly and then increased along in the air flow direction. The authors finally analyzed the effect of tread patterns on the flow field around the tire and revealed the differences between flow characteristics and aerodynamic drag. The results show that, angle of tire lateral groove has great effect on the flow field characteristics such that; the more the angle of lateral groove agrees with the air flow direction, the less the flow separation and flow vortices, and a minimum observable aerodynamic drag. The research provides a guidance for the design of low aerodynamic drag tires, and helps to illustrate the impact of tire aerodynamics on the car body in the future.

Numerical Analysis of an External Flow-Field around a Formula SAE Car Body Based on FLUENT

2014 ◽  
Vol 1039 ◽  
pp. 17-24 ◽  
Author(s):  
Xiao Han Cheng ◽  
Shan Ming Luo ◽  
Xue Feng Chang ◽  
Dan Xie
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Attack Angle ◽  
The Body ◽  
Formula Sae ◽  
Rear Wing

This paper proposed a method to analysis an external flow-field around a Formula SAE car. Firstly, the body of Formula SAE car was designed conforming to the FSAE rules using CATIA. Then, the model of the external flow-field around the vehicle was established using computational fluid dynamic technology. A comparative analysis of the aerodynamic characteristics was made for the body between the conditions of being without the wing package and being with the wing package under different attack angle to get the static pressure graph, the lift force and the drag force then worked out the drag coefficient and confirmed which is the most suitable angle for the wings. The results showed that: the static pressure of the front body, the front part of the tires and the driver’s chest and head is the highest; the body has good streamline since its drag coefficient is 0.385; the rear wings can supply 65% downforce, when the attack angle of the rear wing is set to 8°. Finally, the real mold was fabricated according to the above 3D model and the analysis results. The method presented in this paper can provide theoretical basis and technical parameter for the aerodynamic formation designing and amelioration of the Formula SAE cars. Also it has guiding significance for the design and aerodynamic analysis of the Ordinary Passenger car.

Turbulence Modeling for Thrust Reverser Flow Field Prediction Methods

1992 ◽  
Author(s):  
Robert E. Childs ◽  
Laura C. Rodman ◽  
Peter Bradshaw
Keyword(s):  
Flow Field ◽  
Turbulence Modeling ◽  
Prediction Methods ◽  
Thrust Reverser

scholarly journals Movement of a finite body in channel flow

2016 ◽  
Vol 472 (2191) ◽  
pp. 20160164 ◽  
Author(s):  
Frank T. Smith ◽  
Edward R. Johnson
Keyword(s):  
Reynolds Number ◽  
Channel Flow ◽  
Flow Instability ◽  
Flow Direction ◽  
Finite Size ◽  
The Body ◽  
Thin Body ◽  
Shear Stresses ◽  
Unsteady Interaction ◽  
High Reynolds

A body of finite size is moving freely inside, and interacting with, a channel flow. The description of this unsteady interaction for a comparatively dense thin body moving slowly relative to flow at medium-to-high Reynolds number shows that an inviscid core problem with vorticity determines much, but not all, of the dominant response. It is found that the lift induced on a body of length comparable to the channel width leads to differences in flow direction upstream and downstream on the body scale which are smoothed out axially over a longer viscous length scale; the latter directly affects the change in flow directions. The change is such that in any symmetric incident flow the ratio of slopes is found to be cos ⁡ ( π / 7 ) , i.e. approximately 0.900969, independently of Reynolds number, wall shear stresses and velocity profile. The two axial scales determine the evolution of the body and the flow, always yielding instability. This unusual evolution and linear or nonlinear instability mechanism arise outside the conventional range of flow instability and are influenced substantially by the lateral positioning, length and axial velocity of the body.

Survey on the Indirect Methods of Potential Flow Used for the Optimization of Airships Profile

2014 ◽  
Vol 554 ◽  
pp. 717-723
Author(s):  
Reza Abbasabadi Hassanzadeh ◽  
Shahab Shariatmadari ◽  
Ali Chegeni ◽  
Seyed Alireza Ghazanfari ◽  
Mahdi Nakisa
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Field ◽  
Drag Coefficient ◽  
Body Surface ◽  
Potential Flow ◽  
The Body ◽  
Indirect Methods ◽  
Singularity Method ◽  
Singularity Distribution

The present study aims to investigate the optimized profile of the body through minimizing the Drag coefficient in certain Reynolds regime. For this purpose, effective aerodynamic computations are required to find the Drag coefficient. Then, the computations should be coupled thorough an optimization process to obtain the optimized profile. The aerodynamic computations include calculating the surrounding potential flow field of an object, calculating the laminar and turbulent boundary layer close to the object, and calculating the Drag coefficient of the object’s body surface. To optimize the profile, indirect methods are used to calculate the potential flow since the object profile is initially amorphous. In addition to the indirect methods, the present study has also used axial singularity method which is more precise and efficient compared to other methods. In this method, the body profile is not optimized directly. Instead, a sink-and-source singularity distribution is used on the axis to model the body profile and calculate the relevant viscose flow field.

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