# Aeroaocustic Numerical Analysis of the Vehicle Model

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## Abstract

**:**

## 1. Introduction

## 2. Models and Methods

#### 2.1. Mathematical Model

#### 2.2. Numerical Model

#### 2.2.1. Geometry Model

#### 2.2.2. Discretization

#### 2.2.3. Boundary Conditions

#### 2.2.4. Initial Condition

## 3. Results

#### 3.1. Velocity and Pressure Field in Symmetry Plane

#### 3.2. Steamwise Velocity Profile in Symmetry Plane

#### 3.3. Drag Coefficient

#### 3.4. Sound Pressure Level (SPL)

## 4. Discussion and Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Abbreviations

CFD | Computational Fluid Dynamics |

CAA | Computational Aeroacoustics |

FW-H | Ffowcs Williams–Hawkings |

SST | Shear Stress Transport |

LES | Large Eddy Simulation |

FFT | Fast Fourier Transformation |

VLES | Very Large Eddy Simulation |

RANS | Reynolds-Averaged Navier–Stokes |

EARSM | Explicit Algebraic Stress Model |

DES | Detached Eddy Simulation |

IDDES | Improved Delay Detached Eddy Simulation |

RSM | Reynolds Stress Model |

SA | Spalart–Allmaras |

WA | Wray–Agarwal |

RNG | Renormalization Group |

PRESTO | Pressure Staggering Option |

ERCOFTAC | European Research Community on Flow, Turbulence and Combustion |

OASPL | Overall Sound Pressure Level |

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**Figure 7.**Vortex system in wake (schematic) [9].

**Figure 9.**Streamwise velocity profiles in the symmetry plane $y=0$. Black lines for experimental data, blue dots for model $k-\omega $ SST, red dots for model LES. (

**a**) General view; (

**b**) zoom at the back of the Ahmed body.

**Figure 10.**Velocity error for the $k-\omega $ SST turbulence model. Experimental data are presented as black lines. The unit of the colormap is meter per second (m/s). (

**a**) General view; (

**b**) zoom at the back of the Ahmed body.

**Figure 11.**Velocity error for the LES turbulence model. Experimental data are presented as black lines. The unit of the colormap is meter per second (m/s). (

**a**) General view; (

**b**) zoom at the back of the Ahmed body.

**Figure 14.**Overall sound pressure level in decibels (dBs) around the Ahmed body, measured at receivers for the z-coordinate of 194 mm. View from the top.

Stage | I | II | III |
---|---|---|---|

Convergence criteria | Residuals ${10}^{-4}$ | Residuals ${10}^{-4}$ | Residuals ${10}^{-4}$ + steady value of drag and lift coefficient with fluctuation around mean |

Number of iterations required to achieve the convergence criteria | 411 | 821 | 7500 |

Turbulence model | $k-\omega $ SST | $k-\omega $ SST | LES |

Pressure equation | Second Order | Second Order | Pressure Staggering Option (PRESTO) |

Momentum equation | First Order | Second Order | Bounded Central Differencing |

Relaxation Factor—Pressure | 0.25 | 0.25 | 0.5 |

Relaxation Factor—Momentum | 0.25 | 0.25 | 0.5 |

Drag Coefficient | 0.4409 | 0.3097 | 0.2979 (mean value) |

Lift Coefficient | 0.4177 | 0.2066 | 0.3637 (mean value) |

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**MDPI and ACS Style**

Hamiga, W.M.; Ciesielka, W.B.
Aeroaocustic Numerical Analysis of the Vehicle Model. *Appl. Sci.* **2020**, *10*, 9066.
https://doi.org/10.3390/app10249066

**AMA Style**

Hamiga WM, Ciesielka WB.
Aeroaocustic Numerical Analysis of the Vehicle Model. *Applied Sciences*. 2020; 10(24):9066.
https://doi.org/10.3390/app10249066

**Chicago/Turabian Style**

Hamiga, Władysław Marek, and Wojciech Bronisław Ciesielka.
2020. "Aeroaocustic Numerical Analysis of the Vehicle Model" *Applied Sciences* 10, no. 24: 9066.
https://doi.org/10.3390/app10249066