J. Hydrol. Hydromech., Vol. 74, No. 1 - Early view, 2026, p. 1 - 10, doi: .
Scientific Paper, English

Vighnesh Prasad, Anil Dubey: Role of critical parameters on the rheology and pipeline transportation of concentrated non-Newtonian iron ore slurry

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• Achieving optimal flow characteristics while handling a complex slurry system in the pipeline needs greater attention. This study aims to demonstrate the role of iron ore concentration and size distribution on slurry rheology and their subsequent effect on slurry pipeline transportation. The concentrated iron ore slurries are sheared in the shear rate range between 0.1 – 500 s-1, where the experimental data is well-represented by the Bingham-plastic model. The model parameters are employed to calculate pressure drop and energy consumption. A thorough investigation through rheo-microscopy analysis reinforces the validity of the rheological hypothesis. The rheological analysis reveals the yield-pseudoplastic flow behaviour of iron ore slurries irrespective of particle concentrations and coarse particle addition. The slurry containing iron ore fines contributes to an increase in viscosity, mitigated by introducing coarse particles. Rheo-microscopy suggests that the viscosity reduction is attributed to the obstruction of floc formation and disintegration of the slurry structure. The pressure drop and energy consumption escalate with increasing slurry velocity regardless of pipe diameters. However, these entities decrease by including coarse iron ore particles in slurries. This work advocates optimizing rheology to reduce pipeline transportation costs while handling bulk iron ore with minimum environmental repercussions.
  
  KEY WORDS: Data not availableIron ore; Rheology; Rheo-microscopy; Slurry pipeline transportation; Pressure drop; Specific energy consumption.
  
  Address:
  - Vighnesh Prasad, Department of Pipeline Transport Systems & Societal Technologies, CSIR – Institute of Minerals & Materials Technology, Bhubaneswar, Odisha - 751013, India. Faculty of Engineering Sciences, Academy of Scientific and Innovative Research (AcSIR), CSIR - HRDG, Ghaziabad, Uttar Pradesh - 201002, India. (Corresponding author. Tel.: Fax.: Email: vprasad@immt.res.in)
  - Anil Dubey, Faculty of Engineering Sciences, Academy of Scientific and Innovative Research (AcSIR), CSIR - HRDG, Ghaziabad, Uttar Pradesh - 201002, India.

J. Hydrol. Hydromech., Vol. 74, No. 1 - Early view, 2026, p. 11 - 19, doi: .
Scientific Paper, English

Hossein Sohrabzadeh Anzani, Sameh Ahmed Kantoush, Sohei Kobayashi: Hydraulic Optimization of Symmetric Wart-Type Baffle Spacing for Fish Passage in Open-Channel Flows

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• This study investigates the role of symmetric wart-type baffles in facilitating fish passage under supercritical flow conditions in an open-channel flume. Experiments were conducted in a 7 m long, 0.5 m wide flume with a 2% bed slope at the Ujigawa Hydraulic Laboratory, Kyoto University. The impact of two baffle spacings (20 cm and 30 cm) on hydraulic characteristics was assessed and compared to a smooth channel. Velocity profiles, flow depth, and turbulence intensity were measured across ten longitudinal points to evaluate flow heterogeneity and energy dissipation. Results indicate that baffles significantly reduce flow velocity and create low-velocity resting zones critical for fish migration. The 20 cm spacing configuration proved most effective, offering a balance of reduced velocities (0.5–0.9 m/s) and sufficient hydraulic diversity to support energy-efficient fish passage. In contrast, the 30 cm spacing resulted in higher velocities and reduced low-velocity zones, potentially challenging weaker swimmers. Turbulence intensity was lowest with 30 cm spacing (TImean= 0.053), indicating smoother flow but fewer refuges compared to 20 cm spacing (TImean= 0.069). The smooth channel exhibited uniform, high velocities, unfavorable for most fish species. These findings highlight the importance of optimized baffle spacing in fishway design to enhance river connectivity and support aquatic biodiversity.
  
  KEY WORDS: Fish passage; Baffles; Barriers; Remediation; Ecohydraulics; Turbulence intensity.
  
  Address:
  - Hossein Sohrabzadeh Anzani, Water Resources Research Center, Disaster Prevention Research Institute, Kyoto University, Uji 6110011, Japan. (Corresponding author. Tel.: Fax.: Email: ho.sohrabzadeh@gmail.com)
  - Sameh Ahmed Kantoush, Water Resources Research Center, Disaster Prevention Research Institute, Kyoto University, Uji 6110011, Japan.
  - Sohei Kobayashi, Water Resources Research Center, Disaster Prevention Research Institute, Kyoto University, Uji 6110011, Japan.

J. Hydrol. Hydromech., Vol. 74, No. 1 - Early view, 2026, p. 20 - 35, doi: .
Scientific Paper, English

Manisha Panthi, Brian Mark Crookston, Michele Palermo: Scour evolution for steady and unsteady flow conditions downstream of Type A piano key weirs

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• For the first time a comprehensive analysis for steady and unsteady flow conditions was performed of time-dependent scour processes in non-cohesive sediment downstream of a Type A piano key weir. The evolution and progression of scour of large-scale laboratory experiments were interpreted using an empirical approach and adapting a theoretical model based on the phenomenological theory of turbulence developed elsewhere. The results were within 30% of experimental with the R-squared values of 0.972 for the theoretical model and 0.993 for a calibrated empirical model. Results of this study demonstrate consistent scour evolution kinetics between steady and unsteady flow cases, although in the latter, the maximum scour features were smaller than their steady-state counterparts. This study highlights the novelty of integrating experimental and theoretical frameworks to validate and enhance the design of complex hydraulic structures. Quantitative findings confirm the robustness of first principles-based approaches, offering practical insights and design parameters critical for addressing scour challenges in non-cohesive sediment environments.
  
  KEY WORDS: Temporal scour evolution; Non-cohesive sediment; Scour equilibrium; Stepped flood hydrograph; Unsteady flows.
  
  Address:
  - Manisha Panthi, Utah Water Research Laboratory, Dept. of Civil and Env. Engineering, Utah State University, 8200 Old Main Hill, Logan, UT 84322-8200 USA.
  - Brian Mark Crookston, Utah Water Research Laboratory, Dept. of Civil and Env. Engineering, Utah State University, 8200 Old Main Hill, Logan, UT 84322-8200 USA. (Corresponding author. Tel.: Fax.: Email: brian.crookston@usu.edu)
  - Michele Palermo, DESTEC- Department of Energy, Systems, Territory and Construction Engineering, University of Pisa, Via Gabba 22, 56122 Pisa, Italy.