Searched for: author:"Clemens, F.H.L.R."
(1 - 20 of 85)

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Thota Radhakrishnan, A.K. (author), Poelma, C. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
Transition from laminar to turbulent flow of non-Newtonian fluids is investigated using velocimetry data. These data are obtained by applying particle image velocimetry to images obtained through ultrasound imaging (echography). This yielded the observation of intermittent structures (puffs and slugs) that are formed during transition. Post...
journal article 2020
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Rietveld, M.W.J. (author), de Rijke, D. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Urban runoff (re)mobilises solids present on the street surface and transport them to urban drainage systems. The solids reduce the hydraulic capacity of the drainage system due to sedimentation and on the quality of receiving water bodies due to discharges via outfalls and combined sewer overflows (CSOs) of solids and associated pollutants....
journal article 2020
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Runoff entering urban drainage systems contains suspended solids, which carry pollutants and may cause blockages in downstream parts of the system (for example infiltration facilities). Suspended solids inflow should, therefore, preferably be controlled by solids removal at gully pots. This paper presents the results of lab experiments on the...
journal article 2020
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Meijer, D.H. (author), Post, Johan (author), van der Hoek, J.P. (author), Korving, Hans (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Drinking water distribution networks (WDNs) are a crucial infrastructure for life in cities. Deterioration of this ageing, and partly hidden from view, infrastructure can result in losses due to leakage and an increased contamination risk. To counteract this, maintenance strategies are required to maintain the service level. Information on...
journal article 2020
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Mehta, D. (author), Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes; in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non...
journal article 2020
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Gully pots are utilized for conveying runoff to drainage systems, as well as for reducing the system’s solids loading by retaining suspended solids. However, the accumulation of solids in gully pots reduces their removal efficiency, leading to an increase in solids transport towards the drainage system. This article aims to identify the main...
journal article 2020
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Duinmeijer, S.P.A. (author), Oldenziel, G. (author), Clemens, F.H.L.R. (author)
In order to analyse the flow characteristics of free-surface vortexes and to validate the Burgers vortex model by using stereo particle image velocimetry, experiments are conducted in a 600 mm diameter vortex tank. Measured axial velocities indicate that 10–25% of the flow is transported through the vortex core. The velocity profiles show that...
journal article 2020
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Tscheikner-Gratl, F. (author), Bellos, Vasilis (author), Schellart, Alma (author), Moreno Rodenas, A. (author), Muthusamy, Manoranjan (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author), Shucksmith, James (author), Heuvelink, Gerard B.M. (author)
This paper aims to stimulate discussion based on the experiences derived from the QUICS project (Quantifying Uncertainty in Integrated Catchment Studies). First it briefly discusses the current state of knowledge on uncertainties in sub-models of integrated catchment models and the existing frameworks for analysing uncertainty. Furthermore, it...
review 2019
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Sewer and urban drainage systems deal with the runoff of areas that lack infiltration capacity. During wet weather, solids that are present on the street are (re)mobilised and transported to the drainage system by the runoff. These solids and their associated pollutants can have detrimental effects on receiving water quality. This paper presents...
conference paper 2019
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Tscheikner-Gratl, Franz (author), Caradot, Nicolas (author), Cherqui, Frederic (author), Leitão, Joao P. (author), Langeveld, J.G. (author), Scholten, L. (author), Lepot, M.J. (author), Stegeman, B. (author), Clemens, F.H.L.R. (author)
Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced...
journal article 2019
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Mehta, D. (author), Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
The concentration of domestic slurry has two advantages, it promotes resource recovery (nutrients and biomass) and saves water. But the design of a relevant sewerage requires a clear understanding of the frictional losses incurred during the transport of the slurry. This abstracts describes numerical & CFD-based methods to estimate losses...
conference paper 2019
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Moreno Rodenas, A. (author), Tscheikner-Gratl, F. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Receiving water quality simulation in highly urbanised areas requires the integration of several processes occurring at different space-time scales. These integrated catchment models deliver results with a significant uncertainty level associated. Still, uncertainty analysis is seldom applied in practice and the relative contribution of the...
journal article 2019
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Mehta, D. (author), Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
This article follows from a previous study by the authors on the computational fluid dynamics-based analysis of Herschel-Bulkley fluids in a pipe-bounded turbulent flow. The study aims to propose a numerical method that could support engineering processes involving the design and implementation of a waste water transport system, for...
journal article 2019
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Moreno Rodenas, A. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Water quality environmental assessment often requires the joint simulation of several subsystems (e.g. wastewater treatment processes, urban drainage and receiving water bodies). The complexity of these integrated catchment models grows fast, leading to potentially over-parameterised and computationally expensive models. The receiving water body...
journal article 2019
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Stegeman, B. (author), Langeveld, J.G. (author), Bogaard, T.A. (author), Clemens, F.H.L.R. (author)
Due to the ageing of our underground wastewater infrastructure, leakage of sewers and pressure mains and subsequent infiltration or exfiltration are becoming an increasingly important issue. Herein, we present a novel method to detect and potentially quantify exfiltration from sewer systems under variable flow conditions; the DEST method. The...
conference paper 2019
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Makris, K. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Polyvinyl chloride (PVC) has become one of the dominant construction materials for sewer systems over the past decades, as a result of its reputed merits. However, since PVC sewer pipes have operated for decades in a hostile environment, concern over their longevity has been lately raised by sewer managers in the Netherlands. Towards that...
journal article 2019
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Meijer, D.W.J. (author), Scholten, L. (author), Clemens, F.H.L.R. (author), Knobbe, Arno (author)
Sewer pipes are commonly inspected in situ with CCTV equipment. The CCTV footage is then reviewed by human operators in order to classify defects in the pipes and make a recommendation on possible interventions. This process is both labor-intensive and error-prone. Other researchers have suggested machine learning techniques to (partially)...
journal article 2019
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Moreno Rodenas, A. (author), Bellos, V. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
This work presents a method to emulate the flow dynamics of physically based hydrodynamic simulators under variations of time-dependent rainfall and parametric scenarios. Although surrogate modelling is often employed to deal with the computational burden of this type of simulators, common techniques used for model emulation as polynomial...
journal article 2018
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Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
Information on the rheology of domestic slurries is essential in designing pipeline transportation in novel sanitation systems. As concentrated slurries in their original collected state have wide particle size distribution, with particles up to 2 mm, a wide gap rheometer is used to acquire the rheograms. Rheograms obtained from a wide gap...
journal article 2018
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Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
The much over-looked element in new sanitation, the transport systems which bridge the source and treatment facilities, is the focus of this study. The knowledge of rheological properties of concentrated domestic slurry is essential for the design of the waste collection and transport systems. To investigate these properties, samples were...
journal article 2018
Searched for: author:"Clemens, F.H.L.R."
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