Randomness in flow turbulence around a bridge pier in a sand mined channel

Lade, Abhijit D.; Mihailović, Anja; Mihailoviĉ, Dragutin T.; Kumar, Bimlesh

doi:10.1016/j.physa.2019.122426

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…In spite of sand mining being a local phenomenon, hydromorphological alterations in the fluvial system induced by these activities can extend several kilometres from the mining zone. In our earlier study (Lade et al, 2019), we observed that the flow‐field around a pier located in the proximity of a dredged zone was significantly altered. Higher turbulent stresses in the down‐flow zone and horseshoe vortex zone at the pier front were observed in the presence of an upstream dredged pit.…”

Section: Discussionmentioning

confidence: 73%

“…It is evident from these plots that the morphological effects of in‐stream mining are not localized in a particular region, but observed over the entire streambed on the downstream side of the mining pit. Previous authors reported increased flow turbulence and excess bed shear on the streambed downstream of a pit (Barman, Kumar, & Sarma, 2018; Lade, Mihailović, Mihailović, & Kumar, 2019). Due to a dredged zone, transport of momentum across the flow depth increases, which causes higher turbulent stresses in the downstream of the dredged zone.…”

Section: Resultsmentioning

confidence: 94%

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Streambed instabilities around a bridge pier in a dredged channel

Lade

Kumar

2020

River Research & Apps

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We conducted flume experiments to study the morphological behaviour around a circular pier located downstream of a mining pit. Severe transverse erosion at the pier base as well as lowering of channel bed upstream of the pier was observed because of channel dredging. Streambed instability was analysed based on two non‐dimensional parameters, namely, pier exposure factor and normalized upstream incision depth. The maximum values of both these parameters were observed when the mining pit was dredged closest to the pier. We also observed growth in streambed instability with an increase in flow Reynolds number.

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Section: Discussionmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 94%

Streambed instabilities around a bridge pier in a dredged channel

Lade

Kumar

2020

River Research & Apps

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“…Such cases have been reported in rivers of central Spain, Poland, England, France, and India (Chen and Liu 2009, Brestolani et al 2015, Barman et al 2017. Experimental studies have confirmed the streambed instabilities around piers as well as transverse exposure of piers, because of dredging (Yanmaz and Cicekdag 2000, Lade et al 2019a, 2019b, 2019c, Lade and Kumar 2020. Recent studies have manifested the escalation of turbulent stresses and intensities in the region of sand removal and its downstream side , Barman et al 2018.…”

Section: Introductionmentioning

confidence: 75%

“…Physical model tests were performed in a glass sided flume (17.2 m length and 1.0 m width) having rectangular cross-section, with a flow recirculation arrangement (Lade et al 2019a(Lade et al , 2019b(Lade et al , 2019c. A 0.21 m layer of uniform river sand (Marsh et al 2004) having a median diameter = d 1.1 50 mm and geometric standard deviation ( ) s g as 1.1 was laid at the bottom of entire length of the channel.…”

Section: Methodsmentioning

confidence: 99%

“…Previously, we studied the bursting events and randomness characteristics of turbulence in the proximity of an oblong pier due to the bed excavation using the Kolmogorov complexity spectrum (Lade et al 2019a(Lade et al , 2019b(Lade et al , 2019c. We noticed that dredging causes a wider spread of complexity across the instantaneous velocity scales.…”

Section: Introductionmentioning

confidence: 99%

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Effect of sand mining on the flow hydrodynamics around an oblong bridge pier

2021

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Extraction of sand from riverbed has catastrophic repercussions on aquatic animalia habitat, water quality, and the environment. Alongside, physical alterations in the fluvial hydraulics arising on account of sand mining are also worthy of attention. Flows passing over the pits excavated in a channel have enhanced erosive propensity, which can be a cause of concern for the downstream hydraulic structures. The complex nature of flow interacting with the bridge piers after passing over a mining pit is not fully understood. Experiments were conducted to apprehend the effects of a dredged pit on the turbulence flow-field around an oblong pier. Flow was passed in an erodible sand bed rectangular channel having an oblong pier for the first case. In the second case, a pit was dredged in the mobile bed to replicate a mined channel, and the pier was subjected to the same discharge. The streambed at the approach of the pier experiences greater mean bed shear because of dredging. The amplification of the instantaneous bed shear beneath the turbulent horseshoe vortex (THSV) zone at the pier front is almost twice due to channel dredging. The findings can be useful in understanding the streambed instabilities around bridge piers in mining-infested channels.

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