Train Aerodynamics CFD Simulation in OpenFOAM®
Short Example of using OpenFOAM® CFD Toolbox for analyzing Train Aerodynamics
The Simulation Goal: to reduce the drag coefficient of the train unit
The drag coefficient is extremely important. Drag dramatically affects the consumption of the energy (fuel, electricity). Reducing the drag coefficient is never-ending challenge for engineers designing vehicles.
The Simulation Input: surface model of train unit
The train unit model is consisting of locomotive and three cars. The model is of real scale. It is 62 meters long, 4.6 meters high and 3.5 meters wide. The input is the CAD surface model of the train unit. The computational mesh is created in snappyHexMesh, an automatic OpenFOAM® tool for CFD meshing.
There were performed both steady-state CFD simulation and transient simulation.
The Simulation Input: surface model of train unit
- Incompressible flow model
- Medium: Air
- Viscosity: ν = 1.831e-5 [m2/s]
- Specific Heat Capacity: Cp = 1004.4 [J/kg/K]
- Prandtl number: Pr = 0.7 [ - ]
- Thermal conductivity: λ = 2.61e-2 [W/m/K]
- Train speed: U = 72 [km/h]
- OpenFOAM® Solver: simpleFoam
- Turbulence Model: k-ω SST
- Mesh: snappyHexMesh, hexadominant
- Mesh Size: 5529847 cells
- Mesh Average y+: 272 [-]
- CPU time requirements: 14.05 [core.hours]
- Spatial discretization: 1st order upwind
Properties of Transient CFD Simulation
- Incompressible flow model
- Medium: Air
- Viscosity: ν = 1.831e-5 [m2/s]
- Specific Heat Capacity: Cp = 1004.4 [J/kg/K]
- Prandtl number: Pr = 0.7 [ - ]
- Thermal conductivity: λ = 2.61e-2 [W/m/K]
- Train speed: U = 72 [km/h]
- OpenFOAM® Solver: pisoFoam
- Turbulence Model: SpalartAllmarasDDES
- Mesh: snappyHexMesh, hexadominant
- Mesh Size: 5529847 cells
- Mesh Average y+: 272 [-]
- CPU time (1 second of physical time): 327 [core.hours]
- Spatial discretization: 1st order upwind
Drag Coefficient & Lift Coefficient
| Whole Train | Locomotive | Car 1 | Car 2 | Car 3 | |
|---|---|---|---|---|---|
| Cd | 1.0796 | 0.644212 | -0.0194617 | 0.019639 | 0.454873 |
| Cl | 0.160387 | 0.0135685 | -0.0331584 | 0.00605297 | 0.179977 |
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