Flow structure between freight train containers with implications for aerodynamic drag

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Abstract

Predictions from embedded-LES are presented of a model of a section of a double-stacked freight wagon subjected to different local loading configurations. In total, 15 different upstream (G front ) and downstream (G base ) gap spacings were simulated to characterise the change in the flow topology. The mean flow fields indicate that the inter-wagon flow undergoes a significant topology change over the range of G front =1.77W–3.23W (W= wagon width). For G front ≤1.77W, the mean recirculating flow in the gap covers its entire length. In contrast, for G front ≳3.23W, the complete wake closure for the upstream wagon occurs enabling the upstream shear layers to impinge on the entire downstream surface, in turn, increasing the rate of change of drag force as G front is increased. The change in the wake shedding frequency, directly affecting the base pressure and consequently the drag, due to the variation in G front and G base , is presented.

Original languageEnglish
Pages (from-to)194-206
Number of pages13
JournalJournal of Wind Engineering and Industrial Aerodynamics
Volume188
DOIs
Publication statusPublished - 1 May 2019

Keywords

  • Bluff body flow
  • Computational fluid dynamics (CFD)
  • Freight train
  • Hybrid RANS/LES
  • Train aerodynamics

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