STAR CCM+ - FLOW OVER MB ACTROS TRUCK

Objective

To simulate an external aero simulation over MB Actros with & without container with a Speed of 33.33 m/s and to find the Drag and Lift Coefficient

Models

MB Actros

MB Actros without trailer

Surface Repair

From the above image we can see the number of errors so a surface wrap is required.

Surface Wrap

Base value = 0.05 m

Custom control = surface control for Wind tunnel, absolute size of 2.5m(MB Actros) & 1m(MB Actros without trailer) is given

Contact Prevention = for the rear axle tyres & trailer tyres are given with minimum value of 5 mm.

Mesh

MB Actros

MB Actros(Trailer, because the model is taken while taking a turn)

MB Actros without trailer

Meshers Selected

Surface Remesher

Automatic Surface Repair

Trimmed Cell Mesher

Prism Layer Mesher

Mesh

Base size = 0.08 mm

No. of prism layers = 5

Custom Controls = A Volumetric control over the truck with 100(MB Actros without trailer) & 200(MB Actros) of percentage of base is given.

Surface control for Wind tunnel, absolute size of 2.5m(MB Actros) & 1m(MB Actros without trailer) is given.

Wake control(MB Actros without trailer) of 5 degrees spread angle & 100 percentage of base size is given.

Models selected for the flows

Steady

Gas

Segregated flow

Constant Density

Turbulent

K-Epsilon Turbulence

B.C's

Inlet velocity = 33 m/s

Outlet pressure = 0pa(gauge)

Plots

MB Actros

Residual

Drag

Lift

Outlet Velocity

Inlet Pressure

Scalar velocity scene (Cabin)

Scalar velocity scene (Container)

Streamline scene

Vector scene

Streamline scene(Container)

Vector scene(Container)

MB Actros(Without Container)

Residual

Drag

Lift

Outlet Velocity

Inlet Pressure

Scalar velocity scene (Cabin)

Streamline scene

Vector scene

Cd & Cl values

Conclusion

By observing the simulation the and getting the value of Cd & Cl the truck without the container produces less drag(0.0868) and more lift(0.061) when compared to the truck which produces Cd of 0.1657 & Cl 0.008. The reason for this is because the truck is turning at a curve and the cabin & the container are in contact with air i.e when compared to the truck without container the area of contact with air is more (cabin & container in case 2 only cabin).