# Numerical Simulation of Aerodynamic Characteristics of Electric Vehicles with Battery Packs Mounted on Chassis

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## Abstract

**:**

## 1. Introduction

## 2. Fundamental Theory of Computational Fluid Dynamics

#### 2.1. Governing Equations of Fluid Dynamics

_{P}T, where ${C}_{P}$ is the specific heat capacity. In this way, the energy conservation equation (6) with temperature T as the variable can be obtained.

#### 2.2. Numerical Discretization Method

#### 2.3. Turbulence Simulation Method

## 3. Numerical Simulation Calculation

#### 3.1. Geometric Model of SAE Model

#### 3.2. Computational Domain

#### 3.3. Grid Generation

#### 3.4. Turbulence Model and Wall Function

#### 3.5. Boundary Conditions

## 4. Simulation Results and Discussion

#### 4.1. Grid Number Independence Analysis and Model Verification

^{+}values on the surface of the car. It can be seen from the figure that the y

^{+}values are mainly concentrated from 30 to 160, which satisfies the application of the unbalanced wall function and turbulence model and also verifies the rationality of meshing.

#### 4.2. Aerodynamic Analysis of Electric Vehicle with Battery Packs Mounted on Chassis

#### 4.2.1. Aerodynamic Coefficient Analysis

#### 4.2.2. Outflow and Pressure Field Analysis

#### 4.3. Effect of the Structural Parameters of the Battery Pack on the Aerodynamic Coefficient

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 3.**Grid distribution: (

**a**) Grid distribution of longitudinal symmetry planes; (

**b**) Boundary layer mesh.

**Figure 5.**Underbody streamlines of original model and model with battery pack: (

**a**) Original model; (

**b**) Model with battery pack.

**Figure 6.**Underbody pressure distribution of original model and model with battery pack: (

**a**) Original model; (

**b**) Model with battery pack.

**Figure 7.**Velocity vector comparison of longitudinal symmetric plane in tail region: (

**a**) Original model; (

**b**) Model with battery pack.

**Figure 8.**Turbulence kinetic energy of the original model and the model with a battery pack in the tail region: (

**a**) Original model; (

**b**) Model with battery pack.

Boundary | Type | Numerical Value |
---|---|---|

Inlet | Velocity-inlet | V = 20–40 m/s, Direction is perpendicular to the inlet; turbulence intensity I = 0.5% |

Left, right and top surfaces | Sliding wall boundary | |

Body surface | No sliding wall boundary | |

Ground | Moving wall boundary | V = 20–40 m/s, Direction is opposite to the wind speed |

Outlet | Pressure outlet | Standard atmospheric pressure |

Mesh Quantity/Million | Drag Coefficient | Lift Coefficient | Convergence Time/h |
---|---|---|---|

2.5 | 0.2011 | −0.2011 | 4 |

4.7 | 0.1978 | −0.2076 | 7 |

9.3 | 0.1931 | −0.2139 | 16 |

14.1 | 0.1931 | −0.2140 | 24 |

Wind Speed | 20 m/s | 40 m/s | |||
---|---|---|---|---|---|

Model | Drag Coefficient | Lift Coefficient | Drag Coefficient | Lift Coefficient | |

Original model | 0.1913 | −0.2453 | 0.1931 | −0.2439 | |

Model with battery pack | 0.2296 | −0.2398 | 0.2274 | −0.2374 | |

Variation | 20.0% | 2.2% | 17.8% | 2.7% |

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**MDPI and ACS Style**

Deng, Y.; Lu, K.; Liu, T.; Wang, X.; Shen, H.; Gong, J.
Numerical Simulation of Aerodynamic Characteristics of Electric Vehicles with Battery Packs Mounted on Chassis. *World Electr. Veh. J.* **2023**, *14*, 216.
https://doi.org/10.3390/wevj14080216

**AMA Style**

Deng Y, Lu K, Liu T, Wang X, Shen H, Gong J.
Numerical Simulation of Aerodynamic Characteristics of Electric Vehicles with Battery Packs Mounted on Chassis. *World Electric Vehicle Journal*. 2023; 14(8):216.
https://doi.org/10.3390/wevj14080216

**Chicago/Turabian Style**

Deng, Yaoji, Keyu Lu, Tao Liu, Xufei Wang, Hui Shen, and Junjie Gong.
2023. "Numerical Simulation of Aerodynamic Characteristics of Electric Vehicles with Battery Packs Mounted on Chassis" *World Electric Vehicle Journal* 14, no. 8: 216.
https://doi.org/10.3390/wevj14080216