Дисертації з теми "Vegetated channels"
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Judy, N. D. "Resistance to flow in vegetated channels." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376983.
Повний текст джерелаIsmail, Zulhilmi. "A study of overbank flows in non-vegetated and vegetated floodplains in compound meandering channels." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/7905.
Повний текст джерелаAbdalrazaak, Al-Asadi Khalid A. "Experimental Study and Numerical Simulation of Vegetated Alluvial Channels." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/596001.
Повний текст джерелаSavio, Mario. "Turbulent structure and transport processes in open-channel flows with patchy-vegetated beds." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237016.
Повний текст джерелаNikora, Nina. "Flow structure and hydraulic resistance in channels with vegetated beds." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227600.
Повний текст джерелаYang, Qingjun (Judy Qingjun). "Estimation of the bed shear stress in vegetated and bare channels." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99580.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 69-77).
The shear stress at the bed of a channel influences important benthic processes such as sediment transport. Several methods exist to estimate the bed shear stress in bare channels without vegetation, but most of these are not appropriate for vegetated channels due to the impact of vegetation on the velocity profile and turbulence production. This study proposes a new model to estimate the bed shear stress in both vegetated and bare channels with smooth beds. The model, which is supported by measurements, indicates that for both bare and vegetated channels with smooth beds, within a viscous sub-layer at the bed, the viscous stress decreases linearly with increasing distance from the bed, resulting in a parabolic velocity profile at the bed. For bare channels, the model describes the velocity profile in the overlap region of the Law of the Wall. For emergent canopies of sufficient density (frontal area per unit canopy volume a >/= 4.3m⁻¹ ), the thickness of the linear-stress layer is set by the stem diameter, leading to a simple estimate for bed shear stress.
by Qingjun (Judy) Yang.
S.M.
Maji, S., P. R. Hanmaiahgari, R. Balachandar, Jaan H. Pu, A. M. Ricardo, and R. M. L. Ferreira. "A review on hydrodynamics of free surface flows in emergent vegetated channels." MDPI, 2020. http://hdl.handle.net/10454/17820.
Повний текст джерелаThis review paper addresses the structure of the mean flow and key turbulence quantities in free-surface flows with emergent vegetation. Emergent vegetation in open channel flow affects turbulence, flow patterns, flow resistance, sediment transport, and morphological changes. The last 15 years have witnessed significant advances in field, laboratory, and numerical investigations of turbulent flows within reaches of different types of emergent vegetation, such as rigid stems, flexible stems, with foliage or without foliage, and combinations of these. The influence of stem diameter, volume fraction, frontal area of stems, staggered and non-staggered arrangements of stems, and arrangement of stems in patches on mean flow and turbulence has been quantified in different research contexts using different instrumentation and numerical strategies. In this paper, a summary of key findings on emergent vegetation flows is offered, with particular emphasis on: (1) vertical structure of flow field, (2) velocity distribution, 2nd order moments, and distribution of turbulent kinetic energy (TKE) in horizontal plane, (3) horizontal structures which includes wake and shear flows and, (4) drag effect of emergent vegetation on the flow. It can be concluded that the drag coefficient of an emergent vegetation patch is proportional to the solid volume fraction and average drag of an individual vegetation stem is a linear function of the stem Reynolds number. The distribution of TKE in a horizontal plane demonstrates that the production of TKE is mostly associated with vortex shedding from individual stems. Production and dissipation of TKE are not in equilibrium, resulting in strong fluxes of TKE directed outward the near wake of each stem. In addition to Kelvin–Helmholtz and von Kármán vortices, the ejections and sweeps have profound influence on sediment dynamics in the emergent vegetated flows.
Folorunso, Olatunji Peter. "Physically and numerically modelling turbulent flow in a patchy vegetated open channel." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5578/.
Повний текст джерелаCarraretto, Luca. "Functional characterization of AtTPK3 potassium channel of Arabidopsis thaliana." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3426295.
Повний текст джерелаIl mio progetto di dottorato si è focalizzato sulla caratterizzazione, dal punto di vista biochimico ed elettrofisiologico, di una proteina denominata TPK3 che è predetta di funzionare come canale selettiva per il potassio (K+) ed essere localizzata nei cloroplasti nelle piante superiori,. Questa proteina appartiene alla famiglia dei canali TPK (da Tandem-Pore K+ channels) e mostra omologia di sequenza a un altro canale del K+ studiato nello stesso nostro laboratorio, denominato SynK (Zanetti et al., 2010), a localizzazione tilacoidale ed appartenente al phylum dei Cianobatteri. È stato dimostrato in più esperimenti che il canale SynK è fondamentale per la regolazione della fotosintesi nei Cianobatteri, in considerazione del fenotipo fotosensibile mostrato dai mutanti per il gene synk. Visto la localizzazione predetta del TPK3, è stato ipotizzato in partenza che TPK3 potesse svolgere un ruolo simile nelle piante superiori. Finora nulla si conosceva sulle proprietà di TPK3, ne sui suoi ruoli fisiologici, ne su di un suo eventuale coinvolgimento nella fotosintesi nelle piante superiori; il lavoro contenuto nel progetto presentato ha cercato di chiarire alcuni aspetti salienti delle funzioni di TPK3. Dopo studi di localizzazione subcellulare condotti con tecniche di biochimica e microscopia confocale, il canale TPK3 è stato espresso in E. coli per la successiva caratterizzazione elettrofisiologica in bilayer lipidico planare allo scopo di determinare la sua funzione come canale di K+. L’assenza di mutanti commerciali per il gene tpk3 ha necessitato la messa a punto del suo silenziamento tramite RNA interference del messaggero per la proteina suddetta, al fine di analizzarne i possibili ruoli fisiologici. Le piante silenziate risultanti, sottoposte a differenti condizioni di crescita, sono state studiate in vari esperimenti atti a determinarne vari parametri inclusi quelli fotosintetici. Contemporaneamente allo studio del TPK3, quello di maggior rilievo nel mio dottorato, ho seguito anche altri due filoni di ricerca principali, riguardanti l’uno l’approfondimento delle funzioni di due membri dei Recettori di Glutammato vegetali (GluRs) e l’altro la caratterizzazione degli omologhi del recentemente identificato MCU (Mitochondrial Calcium Uniporter) di Mammiferi. Nella presente tesi è inoltre incluso un manoscritto (Checchetto et al., 2012) per il quale ho collaborato nell’espressione eterologa del canale di K+ calcio-dipendente (SynCaK) di Cianobatteri.
Ferrara, G. "VIRAL ION CHANNEL PRODUCTION FOR STRUCTURAL STUDIES." Doctoral thesis, Università degli Studi di Milano, 2011. http://hdl.handle.net/2434/150558.
Повний текст джерелаFRANCESCO, M. L. DI. "ANALYSIS OF INHERENT PROPERTIES OF ION CHANNELS FROM PBCV-1 CHLORELLA VIRUS AND INFLUENZA A VIRUS." Doctoral thesis, Università degli Studi di Milano, 2011. http://hdl.handle.net/2434/150556.
Повний текст джерелаHamade, Firas Nadim. "Sediment removal from urban runoff using seep berms and vegetative filtration." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50271.
Повний текст джерелаGRENZI, MATTEO. "LONG-DISTANCE TURGOR CHANGES INDUCE SYSTEMIC ACTIVATION OF PLANT GLUTAMATE RECEPTOR-LIKE CHANNELS." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/936093.
Повний текст джерелаThroughout their life plants, being sessile organisms, are continuously exposed to environmental challenges that need to be properly perceived and that require appropriate local and systemic responses. Calcium ion (Ca2+) is a key second messenger in all living beings that couples the perception of extracellular stimuli to characteristics intracellular responses. The specificity of the Ca2+-based signalling is achieved through the generation of specific spatial and temporal transient elevations in the cytosolic Ca2+ concentration [Ca2+]cyt, which are referred to as “Ca2+ signatures”. The interplay of Ca2+ signatures with a toolkit of cognate Ca2+-binding proteins that decode these increases allow the plant to implement a series of tailored physiological responses (e.g., gene expression, metabolism, developmental reprogramming) to withstand the stress. In plants, transient increases in the [Ca2+]cyt have been documented to be involved in several physiological processes including root or pollen tube growth and fertilization, abiotic stress responses, plant-microbe interaction. Ca2+ transients with unique magnitude, frequency, shape, and duration are generated by the orchestrated action of Ca2+ influx and efflux systems that include Ca2+ channels, pumps, and exchangers located at different cellular membranes. Given the importance and universality of Ca2+-based signalling, the identification of actors of the molecular machinery that govern the generation of Ca2+ signals is of primary importance. In this context, the study of Ca2+ dynamics in vivo represents a powerful tool. In the frame of my PhD, I explored the marvellous world of Ca2+ imaging using some of the instruments made available from a vast universe of genetically encoded fluorescent Ca2+ biosensors. I learned and refined techniques to produce high-end images of in vivo Ca2+ dynamics both at the entire organism and single-cell level. The expertise that I acquired allowed me to contribute to different projects, all unified by the common denominator that is the master regulatory role of Ca2+ in many signalling processes. I therefore contributed to the study of: (i) the [Ca2+]cyt responses of root tip cells in response to different amino acids, helping to define the molecular determinants involved in the process (Alfieri et al., 2020); (ii) the characterization of [Ca2+]cyt transients induced by the administration of natural auxins and auxin analogues, and the deciphering of the role of molecular actors involved in the genesis of the auxin-induced [Ca2+]cyt response (Wang, Himschoot, Grenzi et al., 2022); (iii) the development of a novel genetically encoded Ca2+ biosensors to unravel the role of the endoplasmic reticulum in the shaping of the Ca2+ signature in developmental processes, as well as in response to various stimuli (Resentini, Grenzi et al., 2021); (iv) the modulatory effects of chemicals on the spontaneous [Ca2+]cyt oscillations of guard cells that govern the opening and closing of stomata. I also contributed to the preparation of reviews linked to the field of Ca2+ signalling. All the published manuscripts, as well as works in preparation, are attached at the end of this dissertation, to which I kindly redirect the readers. Here, I am presenting the main work of my PhD project which focused on the understanding of how local damages can trigger inducible defence mechanisms in systemic organs and tissues. Systemic responses are mediated by long-distance signalling that requires the activity of Glutamate Receptor-Like channels (GLRs). GLRs are homologs of animal Ionotropic Glutamate Receptors (iGluRs) which are ligand-gated cation channels in the central nervous system. Even though iGluRs are gated through the binding with the L-Glutamate, the mechanism throughout GLRs are activated in planta is poorly understood. As an example, we still do not know if the GLRs binding of amino acids is necessary for their activity. In this PhD thesis, we took the advantage of the recently obtained crystal structure of the Arabidopsis thaliana AtGLR3.3 Ligand Binding Domain (LBD) to identify residues involved in the amino acid-binding. We, therefore, introduced single point mutations in the genome sequence of the AtGLR3.3 gene to prevent or abolish its amino acid-binding, and with the obtained constructs we complemented the glr3.3 KO. By combining high-end imaging, genetics, and bioelectronics we prove that leaf injury, such as wound and burn, and root-applied hypo-osmotic stress induce the systemic apoplastic increase of L-Glutamate that activates GLR channels through their LBD. In addition, our work supports the evidence that long-distance signalling is governed by a systemic change in the turgor state and that GLRs are downstream of it.
Vyplel, Adam. "Návrh revitalizace části Knínického potoka." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409723.
Повний текст джерелаCALAMELLO, CATERINA. "TRP ACTIVE COMPOUNDS FROM FOOD PLANTS AND THEIR PROPERTIES AS ANTIMICROBIAL AND BIOCIDES." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168879.
Повний текст джерелаTkáč, Matěj. "Úprava toku – Luha v Jeseníku n/Odrou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226142.
Повний текст джерелаSmelík, Lukáš. "Návrh metodiky stanovení součinitele drsnosti otevřených koryt." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-234558.
Повний текст джерелаJhang, Nai-Wei, and 張乃薇. "Steady gradually varied flow in vegetated channels." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/44593951708313982953.
Повний текст джерела國立成功大學
水利及海洋工程學系碩博士班
94
The vegetation in the floodplain and along the bank can increase roughness of the ground, retard the flow velocity, and bear some shear force. Hence, it can prevent bed erosion and enhance bank stability. However, the water stage was rise and conveyance of flow was retard due to decrease of wetted cross-sectional area. In recent years, the hydraulic phenomenon about flow resistance for the vegetation is more and more important cause of the ecological engineering methods were used. The purpose of this study was to investigate the effect of vegetation, that include the interrelation between both the flow above and through the vegetation and the vegetation densities, in steady gradually varied flow by laboratory experiment and theoretical analysis. The cylinders were used to simulate the stems of vegetation because of their shapes are similar. The exchange of momentum between the flow above and through the vegetation, and the hydraulic resistance were analyzed by the one-dimensional steady gradually varied flow. Equations derived based on the conservation of mass and momentum may be expressed as : Continuity equation: Momentum equation: The formula of dimensionless turbulent length ratio can be mathematically described in turbulent shear stress on the interface between upper and lower level. The formula was useful for calculating the discharge of the upper and lower level. The results indicated that the influence of the resistance coefficient by submerged cylinders on cylinder densities, submergence ratio, and cylinder Reynolds number. Therefore, the condition with the same submergence ratio in the channel, the dense cylinders decrease in both the resistance coefficient and the flow velocity and increase in water stage when the flow through the submerged dense cylinders. In this study, the one-dimensional numerical model was developed by the finite difference scheme was applied to discrete the governing equations that was steady gradually-varied flow in the vegetated channel and proved by laboratory experiment. The numerical model was applied to simulate the flow depth and discharge in the emergent and submerged vegetated channels well. The results of experiment and simulation indicated that the flow discharge was changed both above and through the vegetation and along the direction of flow. According to the results that were increase in the understanding to the phenomenon of flow through vegetation and application of reality. Moreover, the influence of flow on the difference vegetation density was simulated by model. Keywords:vegetation;steady gradually varied flow;resistance coefficient
Su-Pai, Kao, and 高蘇白. "Velocity distribution and Retardance Coefficient in Vegetated Channels." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/e376bv.
Повний текст джерела國立臺北科技大學
工程科技研究所
97
The vegetation in channels results in loss of energy and retardance of water flow. However, this vegetation helps to stabilize the slopes and bottoms of open channels. Recently, vegetated channels have been used to improve the surface water quality and to reduce the delivery of sediment and nutrient to rivers and swales. Therefore, it is important to understand the velocity distribution of vegetated channels. The velocity distribution above canopy is usually assumed to follow the well accepted logarithmic law, whereas the velocity distribution below canopy is expressed by exponential law or power law. However, logarithmic, exponential and power laws can be affected by some characteristics of vegetation resulting in the sufficiently inaccurate description of velocity distributions in vegetated channels. In this study, and velocity distribution equation based on probability is developed to simulate the velocity distribution of vegetated channels in the submerged condition. An extensive series of laboratory experiments planted with Egeria densa Planch in the channel bed of the flume are carried out to devise and validate the velocity distribution equation. The results indicate that the developed model of velocity distribution have the applicability and capability to simulate the velocity distribution effected by aquatic vegetation. The other important parameter of vegetated channel is retardance coefficient. Manning Equation is widely adopted to estimate open channel flows, and selecting retardance coefficient is always one of the most difficult task for estimating velocity and discharge. In cases of estimating accurate retardance coefficient values of vegetated channels, countless trial and error are to be made before reaching conclusive results due to conditions created by various aquatic plants. The majority of past studies on this subject, however, are established based on terrestrial plants and plastic moulds as laboratorial factors, and only few are done with natural aquatic vegetations. Hence, in this study, two different types of natural aquatic plants are applied to estimate retardance coefficients; and the result indicates that each type of plant affects differently in terms of flow resistance. Analysis of hydraulic parameters indicates there are strong correlations between the retardance coefficient and the Froude number. The Froude number is most important and commonly used parameter of open-channel hydraulics. The retardance coefficient and Froude number are exponentially related. Therefore, the Froude number can replaces the product of velocity and hydraulic radius (VR) to estimate the retardance coefficient, in which VR lacks a physical mean. Additionally, it can be used accurately to estimate velocity and discharge during river and wetland restoration.
Huang, Chuan-I., and 黃釧鎰. "Hydraulic analysis of partly vegetated open channels under submerged situation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/53986982647939684915.
Повний текст джерела國立成功大學
水利及海洋工程學系碩博士班
96
When the flood occurs and water flows above the vegetation in the floodplain, the vegetation can increase roughness and retard the flow velocity so that this can prevent bed erosion and enhance bank stability. In addition, it also maintains ecological condition and increases the value of landscaping entertainment. However, the existence of plants will increase the capacity of the main zone and affect on the sediment transport. Hence, the analysis of the discharge in the mainstream is imperative. The main objective of the present study is to investigate the hydraulic phenomenon of the partly-vegetated channels and the flow capacity of the main zone (non-vegetated zone). In the steady gradually-varied flow, we could derive governing equations of the partly-vegetated open channels under a submerged situation and then design the laboratory experiment. To examine the influence of stems on the experiment, stiff cylinders were used to simulate the stems of the vegetation. Based on our research, some crucial results can be drawn: 1. When the flow moves into vegetated channels, it is found that the stages of each cross section in the vegetated and non-vegetated (main channel) zones are almost the same. By assuming the water level to be the horizontal, the momentum and energy equations were obtained mathematically. 2. The velocity distributions were obviously different between the main channel and vegetated channels (i.e. upper and inner the vegetation). After anallyzing the experimental data, we obtained correction factors ( and ) for the formulas of momentum and energy. ( 4-12 ) ( 4-13 ) 3. In the upstream of the vegetated channels, the velocity distribution is closed to be uniform. It was the spatially-varied flow when the water flows into the vegetated channels and the discharge was increased from the upstream to the downstream, including the non-vegetated zone and inside the vegetation; it was decreased along the channels within the vegetation. Around the exit of the vegetated channels, the discharge of the main zone is decreased with the spatially varied condition. Based on the analysis of the experimental date, we could get the relation between the discharge of the main zone and all cross sections, which can be expressed by (4-3). ( 4-3 ) 4. Based on the assumption that the energy slope was equal to the friction slope in the one- dimension steady gradually-varied flow, we derived the expression of the Manning roughness coefficient from the vegetation steam drag coefficient and friction coefficients of bed and wall. The application of the Manning roughness coefficient was verified to be very well from experiment data, which is within the 10% error. ( 2-37 ) ( 2-40 ) 5. It was over contraction in the partly-vegetated channels if the density of the vegetation is great enough, and then the supercritical flow can be observed in the main zone. The hydraulic jump occurs at the end of the channel, because the flow condition changes from the supercritical flow to the subcritical flow. The discriminant of hydraulic jump could be compared with experimental data, which is express by (4-1): ( 4-1 ) Based on the formulas of the energy equation, Manning rough coefficient, the energy correction factor, as well as the ratio of the discharge within the main zone and all cross sections, the discharge of the main zone can be determined in order to get the capacity of the main zone following the standard step method under the one-dimensional steady gradually varied flow.
Hsu, Shao-Han, and 徐劭涵. "Hydraulic analysis of partly vegetated open channels under emergent situation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/66881585500496079743.
Повний текст джерела國立成功大學
水利及海洋工程學系碩博士班
96
There is a close relationship between the stability of main channel in alluvial river and the dominant discharge. Dominant discharge is defined as the main channel discharge nearby the bankfull stage. As the main channel stage is near or over the bankfull stage, the water will overflow into the floodplain. For the thick vegetated floodplain, the near-bankfull stage flow will not submerge the floodplain vegetation. Because vegetation roughness is always larger than main channel roughness, it is necessary to discuss the influence of floodplain vegetation on main channel discharge to analyze the effect of vegetation for main channel stability and surrounding environmental protection. This research aims to maintain part of the width of the channel without vegetation while the other part lays out vegetation with different density. Meanwhile, to discuss the discharge distribution under the situation that steady gradually varied flow flows through emergent vegetation by theoretical analysis and laboratory experiment, in order to apply to investigate the dominant discharge of alluvial river. From the experimental results, when steady gradually varied flow flows into the emergent partly vegetated open channel from non-vegetated open channel, because of the effect of the vegetation drag force, the main channel discharge increases significant along the flow direction but will be gradually constant. And then it decreases as it is getting close to the outlet. With the experimental observation, it is clear to see as the vegetative density increases, the main channel discharge increases as well. Therefore an analysis of the influence of vegetative density on main channel discharge is needed to be studied. Based on the experimental results, the main channel stage is approximately equal to the vegetation stage in the vegetative reach. Hence the transverse water line is regarded as a horizontal line. By the experimental results, an assumption of the transverse water line as a horizontal line was made in this research, which conducts the momentum equations of vegetation zone, main channel zone, and full cross-section according to the momentum conservation theorem. Because the velocity between main channel and the vegetation are significant different, this research calculates the kinetic energy correction factor and the momentum correction factor according to the experimental velocity data, and then compares with the kinetic energy correction factor and the momentum correction factor calculated with the mean velocity of the vegetation zone and main channel zone. The results show each of them is approaching to each other. Therefore the mean velocity of the vegetation zone and main channel zone are accurate enough to calculate the kinetic energy and the momentum correction factor. Applying Moody chart to obtain the friction factor of the channel bed and wall, and then using the momentum equation of full cross-section to analyze the drag force factor of the vegetation cylinder according to the experimental data. The value is between 0.6 and 1.2, the average value is 0.9. And then using the momentum equation of main channel zone to analyze the non-dimension turbulent mixing length ratio, the square of its value is between 0.01 and 0.45, the average is 0.23. The aforementioned analysis results will be applied to the momentum equations of main channel zone and full cross-section to solve the main channel discharge and cross-section average depth by mathematical method. Because mathematical method is more complicated, based on the experimental data, this research uses dimension analysis method to obtain the experiential formula for the ratio that main channel discharge is divided by full cross-section discharge : (4-13) The value calculated by formula ( 4-13 ) is compared with the experimental value, and the result shows the agreement that it will be applied to estimate the main channel discharge of the emergent partly vegetated open channel with orthogonal cross-section. Due to the drag force and the contraction that vegetations act on the water, the emergent partly vegetated open channel will cause the excessively contraction and the supercritical flow. At the same time, because of the subcritical flow downriver, it will also cause the hydraulic jump. This research conducts the discriminant of the hydraulic jump of emergent partly vegetated open channel to distinguish the hydraulic jump according to the vegetative density of the partly vegetated reach , the ratio that the vegetated width is divided by the full cross-section width , and the Froude number : (2-32) The phenomenon of the hydraulic jump of each run in the experiment is compared with formula ( 2-32 ), the result shows the agreement that it is a practical discriminant of the hydraulic jump. Based on the theory and experimental analysis in this research, it is obviously to see that the partly vegetated open channel will increase the main channel discharge because of the influence of the vegetative density, and even occur the supercritical flow and the hydraulic jump. Therefore applying vegetations to protect the bank should review whether the increasing of main channel discharge will affect the erosion and deposition of the main channel bed or not. Based on the results of this research, it also exhibits that the dominant discharge of main channel in alluvial river should be analyzed according to the vegetative condition of the floodplain.
Caroppi, Gerardo. "Turbulence in partly vegetated channels: Experiments with complex morphology vegetation and rigid cylinders." Tesi di dottorato, 2018. http://www.fedoa.unina.it/12669/1/PhD_Thesis_Caroppi.pdf.
Повний текст джерелаHuai, W., L. Yang, and Yakun Guo. "Analytical solution of suspended sediment concentration profile: relevance of dispersive flow term in vegetated channels." 2020. http://hdl.handle.net/10454/17926.
Повний текст джерелаSimulation of the suspended sediment concentration (SSC) has great significance in predicting the sediment transport rate, vegetation growth and the river ecosystem in the vegetated open channel flows. The present study focuses on investigating the vertical SSC profile in the vegetated open channel flows. To this end, a model of the dispersive flux is proposed in which the dispersive coefficient is expressed as partitioned linear profile above or below the half height of vegetation. The double-averaging method, i.e. time-spatial average, is applied to improve the prediction accuracy of the vertical SSC profile in the vegetated open channel flows. The analytical solution of SSC in both the submerged and the emergent vegetated open channel flows is obtained by solving the vertical double-averaging sediment advection-diffusion equation. The morphological coefficient, a key factor of the dispersive coefficient, is obtained by fitting the existing experimental data. The analytically predicted SSC agrees well with the experimental measurements, indicating that the proposed model can be used to accurately predict the SSC in the vegetated open channel flows. Results show that the dispersive term can be ignored in the region without vegetation, while the dispersive term has significant effect on the vertical SSC profile within the region of vegetation. The present study demonstrates that the dispersive coefficient is closely related to the vegetation density, the vegetation structure and the stem Reynolds number, but has little relation to the flow depth. With a few exceptions, the absolute value of the dispersive coefficient decreases with the increase of the vegetation density and increases with the increase of the stem Reynolds number in the submerged vegetated open channel flows.
the Natural Science Foundation of China (Nos. 11872285 and 11672213), The UK Royal Society – International Exchanges Program (IES\R2\181122) and the Open Funding of State Key Laboratory of Water Resources and Hydropower Engineering Science (WRHES), Wuhan University (Project No: 2018HLG01)
De, Felice Sergio. "Experimental study on the hydrodynamic characteristics of a vegetated channel." Tesi di dottorato, 2008. http://www.fedoa.unina.it/3248/1/TESI_de_felice_sergio.pdf.
Повний текст джерелаMaji, S., D. Pal, P. R. Hanmaiahgari, and Jaan H. Pu. "Phenomenological features of turbulent hydrodynamics in sparsely vegetated open channel flow." 2016. http://hdl.handle.net/10454/8740.
Повний текст джерелаThe present study investigates the turbulent hydrodynamics in an open channel flow with an emergent and sparse vegetation patch placed in the middle of the channel. The dimensions of the rigid vegetation patch are 81 cm long and 24 cm wide and it is prepared by a 7× 10 array of uniform acrylic cylinders by maintaining 9 cm and 4 cm spacing between centers of two consecutive cylinders along streamwise and lateral directions respectively. From the leading edge of the patch, the observed nature of time averaged flow velocities along streamwise, lateral and vertical directions is not consistent up to half length of the patch; however the velocity profiles develop a uniform behavior after that length. In the interior of the patch, the magnitude of vertical normal stress is small in comparison to the magnitudes of streamwise and lateral normal stresses. The magnitude of Reynolds shear stress profiles decreases with increasing downstream length from the leading edge of the vegetation patch and the trend continues even in the wake region downstream of the trailing edge. The increased magnitude of turbulent kinetic energy profiles is noticed from leading edge up to a certain length inside the patch; however its value decreases with further increasing downstream distance. A new mathematical model is proposed to predict time averaged streamwise velocity inside the sparse vegetation patch and the proposed model shows good agreement with the experimental data.
Debasish Pal received financial assistance from SRIC Project of IIT Kharagpur (Project code: FVP)
Shie, Jia-Lun, and 謝家倫. "Establishment of roughness coefficient model for the vegetated-revetment trapezoid channel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/32081272126500674362.
Повний текст джерела萬能科技大學
工程科技研究所
96
Considering the channel slope and vegetated revetment, this research makes the according channel test and analyzes the hydraulic properties on trapezoid channel. The result analyzed from test data shows that Manning’s coefficient of vegetated revetment (nw) increases and then decreases with the channel slope (S) at the same flux (Q) and channel slope (Sw). The nw value is the largest at Sw = 10.4 and then approaches a constant value. Under the same flux, the nw value decreases with S. In addition, the smaller flux has a larger influence on the nw value. Under the same S, the nw value first decreases and then increases with Q. When S = 0.04, the nw value significantly increases with Q. In addition, the larger S has a larger influence on the nw value. The relations of Manning’s coefficient of channel (n) and S have the similar results for those of the nw value and S. However, the n value is smaller than that of the nw value. Applying the linear regression analyses, the relations of the Froude number (NF) and nw and n are given as nw = -0.0029NF2 - 0.0161NF + 0.0667 and n = 0.0049NF2 - 0.0292NF + 0.0556, respectively. In addition, the relation of n - nw is given as n = 2.2544nw2 + 0.7825 nw - 0.0109. The regression functions are helpful to design the practical application in a hydraulic engineering. The influence factors of the hydraulic and channel properties are considered on ecological channel. Applying the dimension analysis, the influence parameters can be changed to dimensionless parameters. The multiple regression analysis of the SPSS software are used to obtain the functions of Manning’s coefficient and dimensionless parameters and the final results are given as and . The percentage differences between the roughness coefficients obtained by the separation-area method and the multiple regression model are -4.89 ~ 7.39 % for the nw valve and -5.29 ~ 6.39 % for the n valve. The result shows that this model can appropriately interpret the test data. The regression functions are helpful to design the practical application in ecological engineering. Under the known of hydraulic conditions for trapezoid channel, these functions can be used to estimate effectively the roughness coefficients of the vegetated revetment and channel on trapezoid channel. In addition, it can promote conveniently the hydraulic design of ecological engineering.
Huang, Yu-Shiuan, and 黃于軒. "Experimental Study on Vegetated Channel Flow Field Using Color Partical Image Velocimetry Method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/92713255792128659132.
Повний текст джерела國立交通大學
土木工程系所
93
There are three types of the reactions of the vegetation: erect, waving and prone when flow passes vegetated channel. This study focuses on the erect type to investigate the influence of different vegetated density on the variation of velocity. The cylinder of resin is used as the model plant, with diameter of 0.65 cm and height of 3 cm. There are seven sets of vegetated density. The characteristic volume ratio is used to represent the vegetated density, and it is defined as ratio of the plants’ volume to unit fluid volume. The flow discharge in the experiment is controlled in the range of 70(l/min)∼90(l/min) and the flow depth is 5 cm in the upstream boundary. Because the flow is affected by the vegetation, the flow field changes rapidly. If the traditional single-point measurement at a time is adopted in the experiment, the variation of the velocity field in the vegetated channel cannot be obtained completely and effectively. Hence, this study adopts non-intrusive color particle image velocimety (CPIV) to measure the vertical 2-D flow field in the vegetated channel. The CPIV method uses Argun laser as the light source, the PCAOM separates the light into blue and green lights and they form a light sheet after emitting on a rotating eight-side mirror, the CCD takes the instantaneous images of vegetated channel flow field, and then obtains the velocity field through the set-up of interrogation window and image analysis. Finally, the associated vorticity can be calculated by the central difference scheme based on the measured velocity components at each point. After measuring the vegetated channel flow field with the CPIV method, the stronger vorticities occur in the interface between air and fluid, near the bed of the vegetated channel and the vicinity of the model plant. In addition, the relationships among the increasing rates of the mean and maximum velocities and the distance from the water surface of the maximum velocity at the top of the third-row model plant with respect to the characteristic volume ratio are also analyzed. It can be found that the exponential relationships exist with high correlation coefficients.