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Characterisation of the granular dynamics at the interface between a pipe and a granular flow in a rotating drum

Particuology 2024年第3期86卷 117-125页

作者： francois Rioual paule Emmanuelle Eva Gbehe Research Unit FRISE National Research Institute for Agriculture Food and the Environment1 Rue Pierre Gilles De Gennes92160AntonyFrance

A new mobile bed heat exchanger is presented in this work which is composed of a flowing granular material in a rotating drum and a cylindrical pipe with potential interest in different energy applications as cooling,heating or heat recovery *** optimal design of the device requires a characterisation of the phenomena involved at the interface between the granular flow and the *** process is modelled by the discrete element method and a global classification of the flow patterns around the pipe is presented with respect to the three main control parameters of the problem:the Froude number,the diameter ratio and the relative filling height of the *** second part is devoted to the characterisation of the structure of the flow at the interface(velocity field,density field)in particular in a so-called Biflow regime where granular motion occurs above as well as below the pipe which is favourable to transfer by convection.A typical behavior at the interface with the pipe consists of a zone I with high velocities of particles at the top of the pipe,a second zone with quasistatic particles or low velocity particles at the front and at the bottom of the pipe and a last zone ll of depletion of particles at the back of the *** Froude number has a limited effect on the features of this structure on the first layer in the range of Froude numbers considered whereas the relative height is a more determinant parameter to control the relative magnitude of velocities in zone I and zone Il as well as the extent of the depletion *** first hydrodynamical characterisation can shed light on the dynamical regimes with improved transfer between the particles and the pipe boundary.

关键词： Granular flow Transfer Heat exchange Mobile bed Boundary condition

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Modelling Estimation of the Available Rainwater Resource in Gbedji-Kotovi Clay Area for Supplying Dikes and Dams

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Open Journal of Modern Hydrology 2020年第2期10卷 30-43页

作者： Kassa Issifou Mounou Sambieni francois de paule codo National Water Institute(INE) University of Abomey-CalaviCotonouBenin

Floods and flows data are useful for dimensioning of dikes and dams which often include evacuation devices that regulate flows to ensure the volumes of water. The objective of this study is to estimate the available water resource in the village of Gbédji-Kotovi, located in the watershed of Couffo river in Benin by using sequentially, the HBV (Hydrologiska Byrans Vattenbalansavdelning) and GR4J (Rural Engineering model with 4 daily parameters) climate models. Hydrographs of water levels are simulated according to the calibration period (1994-1999) different from the validation one (1982-1988). Considering the Nash-Sutcliffe model Efficiency coefficient (NSE), the performance of GR4J model during calibration is slightly higher than the performance of the HBV model, while during the validation, the contrary is noticed. The annual rainfall average simulated is 1117.7 mm/year while the average observed is 1104.6 mm/year over the period 1981-2005. By 2050, on one hand, the annual flow rate values will vary from -19.2 to -11.9%, while the actual evapotranspiration will vary between 0.5 and -5.8;on another hand, the potential evapotranspiration and the annual precipitation remain constant. An average flow of 187 millions m3/year for annual average water depth of 1094 mm is obtained at Lanta rain station, which covers an area of 1664.47 km2, while this flow enabled an average flow of 327.5 millons m3/year to be obtained at the virtual station of our study area of 2908.15 km2. The flow rates corresponding to the return periods of 10, 25 and 50 years vary from 5.51 to 12.67 m3/s at the outlet of the virtual station;while those at the outlet of Lanta station vary from 3.6 to 6.6 m3/s. However, the simulated water quantiles cannot be fully mobilized;because of the uses, they undergo upstream and downstream. Thus, Gbédji-Kotovi locality requires the implementation of an integrated water resource management strategy that includes the construction of dikes and dams.

关键词： Rainwater Modelling Couffo Watershed Gbédji-Kotovi Dikes and Dams

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Steady-State Radial Flow Modeling through the Production Well in the Confined Aquifer of Monzoungoudo,Benin

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Open Journal of Fluid Dynamics 2019年第2期9卷 107-118页

作者： francois de paule codo Babilas Hountondji Martin P.Aina Laboratory for Water Sciences and Technology Department of Water and SanitationNational Water InstituteUniversity of Abomey-CalaviCotonouBenin Physical Mathematics and Applications University of Abomey-CalaviCotonouBenin

This study aims to develop a mathematical analysis for one-dimensional modeling of a radial flow through a production well drilled in a confined aquifer, in the case of steady-state flow conditions. An analytical solution has derived from that expression for estimation of drawdowns according to different flowrates. Through that process, the evaluation of static pressure, the calculation of hydraulic charge due to the waterflow through the well is evaluated, the drawdowns curves are drawn and at last, the obtained curves are analyzed. The curves obtained for the different flow rates have an asymptotic direction, the axis of the hydraulic charges. The variation of the hydraulic charge depends on the radial distance for different flow rates. The P point, is a common point of all curves obtained for different production flowrates in the well. This point is where the well production flowrate is optimum for the optimal hydraulic charge.

关键词： Confined Aquifer Production Well Radial Flow Steady-State Flow Drawdown Cone of depression

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Accessibility Index of Aquatic Environments as an Indicator of Surface Water Vulnerability in Urban Areas:Case of the Okpara Basin(Benin)

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Open Journal of Modern Hydrology 2019年第4期9卷 103-112页

作者： Maurille P.S.Lanmandjèkpogni francois de paule codo Babilas Hountondji Benjamin Kouassi Yao Laboratory of Water Science and Technology(LSTE) National Water Institute(INE)University of Abomey-CalaviCotonouBenin International Chairin Mathematical Physics and Applications(CIPMA) University of Abomey-CalaviCotonouBénin Laboratory of Industrial Processes BriefsEnvironment and New Energy(LAPISEEN)Process Group and EnvironmentNational Polytechnic Institute Houphouet-Boigny(INP-HB)YamoussoukroIvory Coast

Physiographic differences and conditions of use of water resources in anthropogenic basins explain the variability of risk to surface water. Based on the multi-criteria analysis of Saaty, the present work proposes an assessment of the vulnerability of surface water through a three-factor accessibility index: the slope, the subdivision rate and the drainage density of the basin. It is observed that the topographic (slope) and urbanistic (subdivision) conditions are the most important (weighting of 59%, 34%) in front of the hydrographic condition (drainage 6%) with an overall consistency of 2%. Thus, in the Okpara basin in the city of Parakou, the analysis of the vulnerability of surface waters by the accessibility index highlights two groups. The Ganré and Kokouro basins with about 30% of their areas in the low and moderate classes and the Wonka and Dama basins in the very strong class at more than 50% of their areas.

关键词： Accessibility Risk Vulnerability Index Okpara

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Seasonal Variation of Nutrient Pollution and Suspended Solids in the Drainage Network of Okpara Basin in Parakou(North-East of Benin)

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Journal of Environmental Protection 2018年第13期9卷 1359-1371页

作者： Maurille P.S.Lanmandjekpogni francois de paule codo Benjamin K.Yao Martin P.Aina Laboratory of Water Science and Technology(LSTE) National Water Institute(INE)University of Abomey-Calavi(UAC)Abomey-CalaviBenin Laboratory of Industrial Processes BriefsEnvironment and New Energy(LAPISEEN)Process Group and EnvironmentNational Polytechnic Institute Houphouet-Boigny(INP-HB)YamoussoukroIvory Coast

This work presents mainly, the seasonal variation of pollution by nutrients and suspended solids thresholds between the old urban core and the peripheral areas of the city of Parakou on the Okpara basin. The city of Parakou has been experiencing strong demographic and socio-economic growth for about two decades. A total of sixty wastewater samples from twelve sampling sites were collected in 2016 according to the AFNOR standards, between the months of March and April in the dry season, then August, September and October in the rainy season. The descriptive statistic of data (minima-maxima) indicates variations of the parameters as follows: The temperature varies between 27.05 and 30.82, the water is a highly variable pH in the dry season (5.84 ded 3.34 mg/L against 0.45 mg/L for conversely, phosphates are at 6.45 mg/L in the dry season against 2.32 mg/L in the rainy season. The mean concentrations of suspended solids are between 40 mg/L in the rainy season and 0.52 mg/L in the dry season. From the physico-chemical characterization and the chi-square independent test, this work shows mainly two results: On the one hand, apart from phosphates, concentrations of nitrates, nitrites and suspended solids on the Okpara basin in Parakou, are higher in the rainy season than in dry season. This can be explained by the variability of soil leaching and thus shows a relative link between the quality of surface water and the hydrogeomorphic basin conditions shown by the independence test (0.456 decreasing gradient between the

关键词： Pollution Okpara Basin Nutrients Eutrophication

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Migration of Biodegradable Organic Matter in Underlying Soils of Household Waste Dumpsites: A Case Study in Abomey-Calavi, Benin

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Journal of Crystallization Process and Technology 2018年第1期8卷 18-32页

作者： Metogbe B.Djihouessi Sofiath Onifade Martin P.Aina Hervé E.Labité francois de paule codo Laboratoire des Sciences et Techniques de l’Eau(LSTE) Institut National de l’EauUniversitéd’Abomey-Calavi(UAC)CotonouBénin Institut National de l’Eau(INE) Universitéd’Abomey-Calavi(UAC)CotonouBénin

This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigation made consisted in estimating the combined effect of retardation factor and biodegradation on migration processes of leachate, in the underlying soils of household waste dumpsites, without active safety barrier. Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN. A mathematical migration model was developed and solved numerically by finite difference method and implemented with Matlab R2013a. Thus, the calibration of the model was made with electric conductivity data by determining the dispersion coefficient of the studied soils (D = 0.96 cm2/min). Simulations for model verification showed that the established model can perfectly predict the migration of biodegradable organic pollution (BOD5) but did not give conclusive results for the monitoring of nitrogenous organic matter (TKN). The influence of the retardation factor on the migration of biodegradable organic pollutants in soils was linear, while the biodegradation rate of the organic material on migration showed an exponential pattern.

关键词： Waste Dumpsites Pollutants Biodegradability Soil Dispersion Column Test Biodegradable Organic Pollution Nitrogenous Organic Matter

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Geometric Drawing Model of Shape of Water Sections for the Investigation of Solid Flow Transport in the Basin of Mono River in Republic of Benin

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Open Journal of Modern Hydrology 2022年第3期12卷 95-108页

作者： François de paule codo Lauris Senou Apollinaire Tchikpoto department of Water and Sanitation Engineering National Water Institute (INE) University of Abomey-Calavi Republic of Benin Laboratory for Water and Environmental Sciences and Technics National Water Institute (INE) University of Abomey-Calavi Republic of Benin

The hydrologic and hydraulic changings on the behavior of Mono river are the result of the stress involved by human activities, on one hand and the construction of the dam of Nangbéto and the exploitation of sand in downstream of the dam by the population, between Athiémé and Agbanankin on other hand. That effect had also affected the shape of the sections of the river in the context of climate variability. It shows consequently that area is also a trapping area of sediments eroded in downstream of the dam and is responsible for the trapping of sediments in the river. The slope and the flow rate are the main factors of the real capacity of transport of a watercourse. They also determine the transport of solid flows from upstream to downstream. This drawing model established by taking into account the bathymetry of a transversal section of the Mono river at Athiémé, is the first step of a global investigation of the solid flow transport in the basin of Mono river and the boundary condition for the characterization of its hydro-sedimentary dynamics study. It aims to take into account sections and the used technique which consist to measure on one located section as the representative section of the river at Athiémé, by moving the boat used for bathymetry.

关键词： Mono River Bathymetry Geometric Drawing Modelling Hydro-Sedimentary Dynamics Trapping

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Quantification of Carried Sediment Charges through the Outflow in the Basin of Mono River in Benin

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Open Journal of Modern Hydrology 2023年第4期13卷 276-291页

作者： Lauris Senou Raudace Nakou Brice Gbaguidi François de paule codo Apollinaire Tchikpoto Laboratory of Sciences and Technology for Water and Environment (LSTEE) Water National Institute (INE) University of Abomey-Calavi (UAC) Cotonou Bénin

The filling of rivers generated by carried solid deposit is a factor for the raising of height of rivers and thus activates the floods and inundations. The quantification of carried solid flow charges through their characterization and the analysis of hydrosedimentary dynamics is the second step of the investigation of the solid flow transport in the Mono river. This study aims to quantify the volume of trapped sediments in function of the variation of the geometry of the shape of sections of the river depending of the slope and the flow rate therefore to evaluate the capacity of transport of eroded solid flows of a watercourse from upstream to downstream. Consequently, the decreasing percentage of deposited alluvium from upstream to downstream is calculated along Mono river. Thus the drawn granulometric curve of sediments and the determinate granulometric characteristics of sediments permit to quantify the carried sediment charges at each chosen section with Engelund-Hansen model in Mono river.

关键词： Basin of Mono River Hydro-Sedimentary Dynamics Solid Flow Transport Engelund-Hansen Model

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Structural and Mineralogical Characterization of the Clayey deposits of Gbédji-Kotovi in Lama depression, Bénin

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Open Journal of Applied Sciences 2023年第1期13卷 1-14页

作者： Kassa Issifou Mounou Sambieni François de paule codo Christophe Kaki Daouda Mama Guy Apollinaire Mensah Mina Amharref National Center for Testing and Research for Public Networks (CNERTP) Cotonou Benin Laboratory of Science and Technology for Water and Environment Water National Institute (INE) University of Abomey Calavi Bénin department of Earth Sciences University of Abomey Calavi Benin Applied Hydrology Laboratory Water National Institute (INE) University of Abomey Calavi Bénin National Agricultural Research Institute of Benin (INRAB) Abomey-Calavi Bénin Faculty of Sciences and Technology Abdelmalek Essaadi University Tangier Morocco

The objective of the study was to characterize the clays of the Lama depression in Benin. Macroscopic examination of hand soundings, dynamic penetration test and stratigraphic correlation of water borehole logs, as well as scanning electron microscopy (SEM) combined with energy-dispersive X-ray microanalysis (EDX) method were made on compact or stratified clays. The large grains are embedded in a sintered matrix. The texture is heterogeneous and open, including quartz, carbonates and organic matter. The fine fraction is dominated by mineral paragenesis characterizing Kaolinite-Quartz-Calcite-Gypsum dioctahedral smectites composed of: Oxygen, Silica, Carbon, Aluminum, Iron, Zinc, Titanium and Magnesium. This smectic and regular structure includes coarse grains of the order of 800 μm. The pore diameters vary from 130 μm to 1.14 μm. The inter-particle porosity is poorly developed unlike the inter-aggregate pores larger than 0.05 μm. The texture is laminar and shows elongated turbo static particles with more or less rounded edges and honeycomb particles. Quartz and carbonates induce an increase in heterogeneities which develop mechanical sensitivity and hydraulic conductivity. High contents of silica, iron or aluminum and low contents of calcium and magnesium, as well as the presence of other trace elements suggest an alumino-ferriferous clay resulting from the hydrothermal alteration of the acid granite massif. These heterogeneities promote less tortuous pores or paths, making these clays more permeable. Finally, other stabilization studies and improvements to hydraulic products and binders should favor the use of the studied clay as improved backfill or drilling muds.

关键词： Lama depression Clays of Gbédji-Kotovi Structure of Clays Mineralogy of Clays Scanning Electron Microscopy

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