Simulations of flow around a simplified train model with a drag reducing device
Paper i proceeding, 2012
Partially Averaged Navier Stokes is used to
simulate the flow around a simple train model.
The train model has previously been studied in
wind tunnel experiments and has a length to
height/width ratio of 7:1. The Reynolds number
based on the height of the train model is 0.37 x 10^6.
For this Reynolds number, the flow separates from
the curved leading edges on the front then attaches
again on the roof and sides forming a boundary
layer there before separating in the wake. The first
case is of the natural flow around the train model
where direct comparison to experimental data of drag
coefficient and pressure coefficient are made. In the
second case an open cavity is placed on the base
of the train model with the aim of reducing the
overall drag on the model. The results show that the
drag for model with the cavity is reduced by some
10% compared to the drag of the natural case. The
agreement to experimental data for the natural case
is not perfect but the general features in the flow field
are simulated correctly.