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.



train-aerodynamics cfd openfoam model view

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.

train-aerodynamics cfd openfoam model view


There were performed both steady-state CFD simulation and transient simulation.



train-aerodynamics cfd openfoam model view


Properties of Steady-State 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: 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
train-aerodynamics cfd openfoam model view

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

train-aerodynamics cfd openfoam model view

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
train-aerodynamics cfd openfoam model view




train-aerodynamics cfd openfoam model view




train-aerodynamics cfd openfoam model view




train-aerodynamics cfd openfoam model view




train-aerodynamics cfd openfoam model view




train-aerodynamics cfd openfoam model view



Please contact us for further information.





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