Variable density bore interaction with block obstacles

Long Jiang, Alistair G.L. Borthwick, Tamás Krámer, János Józsa

Research output: Contribution to journalArticle

4 Citations (Scopus)


A horizontally variable density flow model is used to simulate hydraulic bore interactions with idealised urban obstacles. The 2D non-linear shallow water equations are solved using a second-order Monotonic Upstreamcentered Schemes for Conservation Laws-Hancock Godunov-type HLLC approximate Riemann scheme. Validation test results are reported for wave propagation over a hump, a constant-density circular dam break and two 1D dam breaks involving different spatial distributions of solute concentration. Detailed parameter studies are then considered for hydraulic bore interactions with single and multiple-square obstacles under subcritical, critical and supercritical flow conditions. In all cases, reflected and diffracted wave patterns are generated immediately after the bore impacts the obstacle(s). Later, the incident bore reconstitutes itself downstream of the obstacle(s). Variable density flows are also considered, with the upstream volumetric concentrations set to values corresponding to water-sediment mixture densities of 1165 and 1495 kg/m3. It is found that the upstream Froude number, gap spacing between obstacles and upstream to downstream density difference influence the strength of the bore-structure interaction, run-up at the front face of the obstacle(s), and subsequent wave-wave interactions.

Original languageEnglish
Pages (from-to)223-237
Number of pages15
JournalInternational Journal of Computational Fluid Dynamics
Issue number4
Publication statusPublished - Apr 1 2011



  • Bores
  • Godunov scheme
  • Riemann solver
  • Shallow water equations
  • Urban flooding

ASJC Scopus subject areas

  • Computational Mechanics
  • Aerospace Engineering
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Mechanics of Materials
  • Mechanical Engineering

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