Double-averaged kinetic energy budgets in flows over mobile granular beds: insights from DNS data analysis

Konstantinos Papadopoulos* (Corresponding Author), Vladimir Nikora, Bernhard Vowinckel, Stuart Cameron, Ramandeep Jain, Mark Stewart, Christopher Gibbins, Jochen Fröhlich

*Corresponding author for this work

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The equations for double-mean, form-induced and spatially averaged turbulent energy budgets are employed to analyse data from direct numerical simulations of turbulent open-channel flows over transitionally rough mobile beds with intermediate flow submergence. Two scenarios were considered related to (i) near-critical bed condition, and (ii) fully mobile bed condition. The bed was composed of a layer of mobile spherical particles moving on the top of one layer of fixed particles of the same size. Data analysis showed the leading energy exchanges between double-mean, form-induced, turbulent flow field contributions as well as particle motions. Above the fixed particles tops, the turbulent flow receives kinetic energy directly from the mean flow as well as from moving bed particles, which in turn also receive energy from the mean flow. For near-critical bed condition, particle aggregations enhanced mean-flow heterogeneity, strengthened turbulent stresses and their effects on the flow, while at increased bed-mobility, energy transport mechanisms became weaker and conversions induced by viscous stresses and pressure became stronger.

Original languageEnglish
Pages (from-to)653-672
Number of pages20
JournalJournal of Hydraulic Research
Issue number4
Early online date8 Nov 2019
Publication statusPublished - Nov 2019

Bibliographical note

The authors gratefully acknowledge the Centre for Information Services and High Performance Computing (ZIH), Dresden, the Jülich Supercomputing Centre (JSC) and the High Performance Computing Service (Maxwell) of the University of Aberdeen for providing computing time. The authors would like to thank Professor Francesco Ballio and two anonymous reviewers for their helpful comments that contributed to improving the final version of this manuscript.

This study was part of the research project “Hydrodynamic Transport in Ecologically Critical Heterogeneous interfaces” (HYTECH), the support of which, under the European Union's Seventh Framework Programme (Marie Curie PFP7-PEOPLE-2012-ITN, European Commission [grant agreement number 316546]), is gratefully acknowledged. Financial support was also provided by the grantsp3 10.13039/501100000266 Engineering and Physical Sciences Research Council (EPSRC), UK, [grant EP/K041088/1] and the German Research Foundation (DFG), [project FR 1593/5-2]. B. Vowinckel and R. Jain gratefully acknowledge the scholarships respectfully provided by the Alexander von Humboldt Foundation and Saxon Scholarship Program, Germany.


  • Double-averaging methodology
  • flow–sediment interactions
  • mean kinetic energy balance
  • mobile-granular beds
  • turbulent kinetic energy
  • turbulent open-channel flows
  • sediment transport
  • overland flows
  • simulation
  • flow-sediment interactions
  • turbulence
  • open-channel
  • immersed boundary method


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