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Artículos de revistas sobre el tema "Bed roughness"

Autor: Grafiati

Publicado: 1 de febrero de 2025

Última modificación: 31 de julio de 2025

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1

Lang, Shinan, Ben Xu, Xiangbin Cui, et al. "A self-adaptive two-parameter method for characterizing roughness of multi-scale subglacial topography." Journal of Glaciology 67, no. 263 (2021): 560–68. http://dx.doi.org/10.1017/jog.2021.12.

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AbstractDuring the last few decades, bed-elevation profiles from radar sounders have been used to quantify bed roughness. Various methods have been employed, such as the ‘two-parameter’ technique that considers vertical and slope irregularities in topography, but they struggle to incorporate roughness at multiple spatial scales leading to a breakdown in their depiction of bed roughness where the relief is most complex. In this article, we describe a new algorithm, analogous to wavelet transformations, to quantify the bed roughness at multiple scales. The ‘Self-Adaptive Two-Parameter’ system ca

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2

Faruque, Md Abdullah Al, and Ram Balachandar. "Roughness effects on turbulence characteristics in an open channel flow." Canadian Journal of Civil Engineering 37, no. 12 (2010): 1600–1612. http://dx.doi.org/10.1139/l10-098.

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A comprehensive study was carried out to understand the effect of roughness on the turbulence characteristics of flow in an open channel. To this end, tests were conducted with four different types of bed surface conditions at two different Reynolds number (Re = 47 500 and 31 000). This includes the use of an impermeable smooth bed, impermeable rough bed, permeable sand bed, and an impermeable bed with distributed roughness. The roughness is generated using sand grains of median diameter 2.46 mm. The effect of bed roughness is seen to have penetrated through most of the flow depth, disputing t

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3

A.Merry, Marwa. "EXPERIMENTAL STUDY FOR DETERMINE MANNING'S COEFFICIENT WITH DIFFERENT SLOPES AND CHANNEL BED MATERIALS." Kufa Journal of Engineering 8, no. 3 (2017): 76–88. http://dx.doi.org/10.30572/2018/kje/8031160.

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Water resources and hydraulic engineering projects have been upward rapidly in all over the world, accordingly the prediction of roughness coefficient is essential criteria to design open channels, and related hydraulic structures. The aims of this research are to find out the effect of changing beds materials and discharge on coefficient of roughness (n), the beds that used in the tests are smooth which represented by original channel bed (steel plate), rough bed material which is a gravel bed and waved bed .The experimental work was performed in a rectangular flume with dimension of (15 m* 0

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4

Irzooki, Raad Hoobi, and Ayad Saoud Najem. "Experimental Investigation for Free Overfall of Flow in Semi-circular Channels." IOP Conference Series: Earth and Environmental Science 1120, no. 1 (2022): 012010. http://dx.doi.org/10.1088/1755-1315/1120/1/012010.

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Abstract In the present paper, the effects of diameter, bed slopes, and bed roughness on free overfall flow of semi-circular channels were investigated experimentally. For this purpose, three models of semi-circular channels with free overfall were built and installed in a 6m long laboratory flume. These three models were 250 cm long and had varying diameters 160, 200, and 250 mm. Four different bed slopes (S) were used in each of these models (0, 0.004, 0.008, and 0.012). For each bed slope, three sand particle sizes were used to roughen the bed (1.18mm, 2.36mm, and 4.75mm). For each model, t

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5

Majeed, Hayder Q., Ali M. Ghazal, and Basheer Al-Hadeethi. "Experimental and Numerical Study of Open Channel Flow with T-Section Artificial Bed Roughness." Mathematical Modelling of Engineering Problems 9, no. 6 (2022): 1589–95. http://dx.doi.org/10.18280/mmep.090619.

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Experimental and numerical studies have been conducted on the effects of bed roughness elements such as cubic and T-section elements that are regularly half-channel arrayed on one side of the river on turbulent flow characteristics and bed erosion downstream of the roughness elements. The experimental study has been done for two types of bed roughness elements (cubic and T-section shape) to study the effect of these elements on the velocity profile downstream the elements with respect to different water flow discharges and water depths. A comparison between the cubic and T-section artificial b

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6

Nikora, Vladimir I., Derek G. Goring, and Barry J. F. Biggs. "On gravel-bed roughness characterization." Water Resources Research 34, no. 3 (1998): 517–27. http://dx.doi.org/10.1029/97wr02886.

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7

FALCINI, FRANCESCA A. M., DAVID M. RIPPIN, MAARTEN KRABBENDAM, and KATHERINE A. SELBY. "Quantifying bed roughness beneath contemporary and palaeo-ice streams." Journal of Glaciology 64, no. 247 (2018): 822–34. http://dx.doi.org/10.1017/jog.2018.71.

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ABSTRACTBed roughness is an important control on ice-stream location and dynamics. The majority of previous bed roughness studies have been based on data derived from radio-echo sounding (RES) transects across Antarctica and Greenland. However, the wide spacing of RES transects means that the links between roughness and flow are poorly constrained. Here, we use Digital Terrain Model/bathymetry data from a well-preserved palaeo-ice stream to investigate basal controls on the behaviour of contemporary ice streams. Artificial transects were set up across the Minch Palaeo-Ice Stream (NW Scotland)

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8

Fredsøe, J., B. M. Sumer, T. S. Laursen, and C. Pedersen. "Experimental investigation of wave boundary layers with a sudden change in roughness." Journal of Fluid Mechanics 252 (July 1993): 117–45. http://dx.doi.org/10.1017/s0022112093003696.

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This study deals with turbulent oscillatory boundary-layer flows over a plane bed with a sudden spatial change in roughness. Two kinds of ‘change in the roughness’ were investigated: in one, the roughness changed from a smooth-wall roughness to a roughness equal to 4.8 mm, and in the other, it changed from a roughness equal to 0.35 mm to the same roughness as in the previous experiment (4.8 mm). The free-stream flow was a purely oscillating flow with sinusoidal velocity variation. Mean flow and turbulence properties were measured. The Reynolds number was 6 × 106 for the major part of the exper

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9

Devi, Kalpana, Prashanth Reddy Hanmaiahgari, Ram Balachandar, and Jaan H. Pu. "A Comparative Study between Sand- and Gravel-Bed Open Channel Flows in the Wake Region of a Bed-Mounted Horizontal Cylinder." Fluids 6, no. 7 (2021): 239. http://dx.doi.org/10.3390/fluids6070239.

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In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake reg

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10

Kashefipour, Seyed Mahmood, Mehdi Daryaee, and Mehdi Ghomeshi. "Effect of bed roughness on velocity profile and water entrainment in a sedimentary density current." Canadian Journal of Civil Engineering 45, no. 1 (2018): 9–17. http://dx.doi.org/10.1139/cjce-2016-0490.

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In this study, the effect of bed roughness on velocity profile and water entrainment in a sedimentary density current for Richardson numbers of 1.2–7 (subcritical flow conditions) was investigated. Experiments were carried out in a tilting flume with four different bed slopes, four roughness heights, and two fluid densities of sedimentary density currents. The results showed that bed roughness significantly affects the general shapes of velocity profiles, especially in the wall region. Two empirical equations were developed as the functions of the relative roughness for the wall and jet region

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11

Khechiba, Haroun, Ali Ghomri, Djamel Besser, Ibtissam Herri, and Salim Khechana. "Experimental study of the sequent depths ratio of the hydraulic jump in a rectangular compound channel with rough main and minor beds and zero slope." STUDIES IN ENGINEERING AND EXACT SCIENCES 6, no. 1 (2025): e13139. https://doi.org/10.54021/seesv6n1-003.

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Hydraulic jumps, the rapid transitions from supercritical to subcritical flow, are crucial for energy dissipation in flood management structures. This study aims to address this knowledge gap by experimentally analyzing the effect of bed roughness on the sequent depth ratio of hydraulic jumps in a rectangular compound channel. Laboratory experiments were conducted in a rectangular compound channel with two distinct roughness zones: the primary bed (main channel) and the secondary bed (floodplain). Uniform plastic granules were used to simulate varying roughness conditions. Results indicated a

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12

Ding, Lei, and Qing-He Zhang. "LATTICE BOLTZMANN SIMULATION TO CHARACTERIZE ROUGHNESS EFFECTS OF OSCILLATORY BOUNDARY LAYER FLOW OVER A ROUGH BED." Coastal Engineering Proceedings 1, no. 32 (2011): 3. http://dx.doi.org/10.9753/icce.v32.sediment.3.

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The 3-D lattice Boltzmann method was applied to characterize roughness effects of oscillatory boundary layer flow over a rough bed. The direct numerical simulation was carried out and the flow resistance of the flat and fixed bed was investigated. The position of the theoretical bed, equivalent roughness height and the behavior of friction factor at small values of relative roughness were obtained using the log-fit method.

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13

Bertin, Stephane, Jane Groom, and Heide Friedrich. "Grain and bedform roughness properties isolated from gravel-patch DEMs." E3S Web of Conferences 40 (2018): 04005. http://dx.doi.org/10.1051/e3sconf/20184004005.

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Remote sensing of gravel-bed patches and resulting high-resolution digital elevation models (DEMs) allow for the identification of various spatial scales of surface roughness. Thus far, dimensions relating to grain and bedform roughness scales have been determined using semivariograms or equivalent structure/autocorrelation functions. However, it is difficult to clearly differentiate roughness scales and separate analysis of roughness properties is not possible. This study examines the use of moving-window detrending on gravel-patch DEMs for isolating grain and bedform roughness and their resp

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14

Humbyrd, Chelsea Joy, and Ole Secher Madsen. "PREDICTING MOVABLE BED ROUGHNESS IN COASTAL WATERS." Coastal Engineering Proceedings 1, no. 32 (2011): 6. http://dx.doi.org/10.9753/icce.v32.sediment.6.

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Accurately predicting movable bed roughness is essential to the analyses of transport processes, but when the bottom is rippled, as it commonly is in the coastal environment, characterizing the roughness is less straightforward than when the bottom is flat. The common method of predicting roughness, while effective, unnecessarily predicts ripple geometry and requires a model-dependent factor, which varies widely, relating ripple geometry and bottom roughness. We have therefore developed an alternative, more direct method of predicting bed roughness in the ripple regime: the wave energy dissipa

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15

Chen, Yifan, Feifeng Cao, Weiping Cheng, and Bin Liu. "Enhancing the Accuracy of Water-Level Forecasting with a New Parameter-Inversion Model for Estimating Bed Roughness in Hydrodynamic Models." Applied Sciences 13, no. 7 (2023): 4551. http://dx.doi.org/10.3390/app13074551.

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The accurate and efficient estimation of bed roughness using limited historical observational data is well-established. This paper presents a new parameter-inversion model for estimating bed roughness in hydrodynamic models that constrains the roughness distribution between river sections. The impact of various factors on the accuracy of inversed roughness was analyzed through a numerical experiment with the number of measurement stations, observed data amount, initial bed roughness, observational noise, and the weight of the regularization term. The results indicate that increasing the number

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16

Rippin, D. M., D. G. Vaughan, and H. F. J. Corr. "The basal roughness of Pine Island Glacier, West Antarctica." Journal of Glaciology 57, no. 201 (2011): 67–76. http://dx.doi.org/10.3189/002214311795306574.

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AbstractWe assess basal roughness beneath Pine Island Glacier (PIG), West Antarctica, based on a recent airborne radio-echo sounding dataset. We identify a clear relationship between faster ice flow and decreased basal roughness in significant parts of PIG. The central portion and two of its tributaries are particularly smooth, but the majority of the tributaries feeding the main trunk are rougher. We interpret the presence of a smooth bed as being a consequence of the deposition of marine sediments following disappearance of the West Antarctic ice sheet in the Pliocene or Pleistocene, and, co

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17

Balachandar, Ram, and V. C. Patel. "Flow over a fixed rough dune." Canadian Journal of Civil Engineering 35, no. 5 (2008): 511–20. http://dx.doi.org/10.1139/l08-004.

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Using a laser Doppler velocimeter (LDV) system, experiments were carried out to obtain detailed information on the flow over a long train of fixed two-dimensional rough-wall dunes. The experiments provide quantitative data on conventionally averaged velocity and turbulence parameters, as well as insights on the flow structures that play a crucial role in sediment transport. The results indicate that the shape of the dunes has a major influence on the flow features, whereas the effect of near-bed roughness is limited to the wall region extending to a distance of about 80% of the dune height abo

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18

Shiba, Shamiran Jargess, Naeema Thaher Aaref, and Shaker A. Jalil. "Properties of Hydraulic Jump on Horizontal Rough Beds." Zanin Journal of Science and Engineering 1, no. 2 (2025): 01–09. https://doi.org/10.64362/zjse.22.

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Hydraulic jumps are essential for dissipating the kinetic energy of high-velocity flows downstream of hydraulic structures such as spillways, drops, chutes, and gates. Effective energy dissipation is critical to prevent scouring and structural damage, and one of the most influential factors in enhancing this dissipation is the roughness of the stilling basin floor. This study investigates how varying bed roughness affects hydraulic jump characteristics in open channel flow. Five-bed conditions were tested, including a smooth surface and four different gravel bed roughness heights: 1.13 cm, 1.5

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19

Katopodis, C., and H. K. Ghamry. "Hydrodynamic and physical assessment of ice-covered conditions for three reaches of the Athabasca River, Alberta, Canada." Canadian Journal of Civil Engineering 34, no. 6 (2007): 717–30. http://dx.doi.org/10.1139/l07-026.

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Water is needed for oil sand developments in the lower Athabasca River basin of northern Alberta, Canada, and is also a key consideration from an ecological and fish habitat perspective, particularly in winter when river flows are at their lowest. Efforts to establish an appropriate flow management regime for the lower Athabasca included revision of River2D, a fixed bed, depth-averaged finite element model, available from www.river2d.ca, to predict hydraulics with a partial or total ice cover. Hydrometric surveys from three reaches of the Athabasca River were used to test the model, assess dif

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20

Warmink, J. J. "Dune dynamics and roughness under gradually varying flood waves, comparing flume and field observations." Advances in Geosciences 39 (August 7, 2014): 115–21. http://dx.doi.org/10.5194/adgeo-39-115-2014.

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Abstract. Accurate forecasts of bed forms and their roughness during a flood wave are essential for flood management. Bed forms remain dynamic even under steady discharge and are subject to a continuous process of creations and destructions of individual bed forms. Dune evolution during the rising limb of a flood wave is quite well understood and can be modeled. However, dune evolution during the falling limb remains poorly understood. The objective of this paper is to explain the bed form evolution and roughness during the receding limb of fast flood waves. Therefore, bed profiles of two flum

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21

Domhof, Boyan C. A., Koen D. Berends, Aukje Spruyt, Jord J. Warmink, and Suzanne J. M. H. Hulscher. "Discharge and location dependency of calibrated main channel roughness: Case study on the River Waal." E3S Web of Conferences 40 (2018): 06038. http://dx.doi.org/10.1051/e3sconf/20184006038.

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To accurately predict water levels, river models require an appropriate description of the hydraulic roughness. The bed roughness increases as river dunes grow with increasing discharge and the roughness depends on differences in channel width, bed level and bed sediment. Therefore, we hypothesize that the calibrated main channel roughness coefficient is most sensitive to the discharge and location in longitudinal direction of the river. The roughness is determined by calibrating the Manning coefficient of the main channel in a 1D hydrodynamic model. The River Waal in the Netherlands is used a

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22

Lau, Kok-Tee, Mastura Mohammad Taha, Syahibudil Ikhwan Abdul Kudus, and See Ern Chung. "EFFECT OF PRINT BED’S HEAT FLOW ON CURLING AND SURFACE ROUGHNESS OF FDM-PRINTED ABS SAMPLE." Jurnal Teknologi 85, no. 2 (2023): 211–22. http://dx.doi.org/10.11113/jurnalteknologi.v85.18610.

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The optimization of printing parameters, in particular the print bed aspect, is essential for the further improvement of print quality. This paper investigates the effect of the print bed’s heat flow and surface properties (i.e. materials and surface roughness) on the curling defect and surface roughness of the ABS-based dog bone designed print. The print bed temperature is varied, and the corresponding heat flow is measured using a portable heat flow meter. The maximum z deflection (curling) of the print is characterized using Geomagic Control X metrology software by measuring the dimension d

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23

MIGNOT, EMMANUEL, D. HURTHER, and E. BARTHELEMY. "On the structure of shear stress and turbulent kinetic energy flux across the roughness layer of a gravel-bed channel flow." Journal of Fluid Mechanics 638 (October 7, 2009): 423–52. http://dx.doi.org/10.1017/s0022112009990772.

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This study examines the structure of shear stress and turbulent kinetic energy (TKE) flux across the roughness layer of a uniform, fully rough gravel-bed channel flow (ks+ ≫ 100, δ/k = 20) using high-resolution acoustic Doppler velocity profiler measurements. The studied gravel-bed roughness layer exhibits a complex random multi-scale roughness structure in strong contrast with conceptualized k- or d-type roughness in standard rough-wall flows. Within the roughness layer, strong spatial variability of all time-averaged flow quantities are observed affecting up to 40% of the boundary layer heig

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24

López, Raúl, and Javier Barragán. "Equivalent Roughness of Gravel-Bed Rivers." Journal of Hydraulic Engineering 134, no. 6 (2008): 847–51. http://dx.doi.org/10.1061/(asce)0733-9429(2008)134:6(847).

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25

Wu, Weiming, and Sam S. Y. Wang. "Movable Bed Roughness in Alluvial Rivers." Journal of Hydraulic Engineering 125, no. 12 (1999): 1309–12. http://dx.doi.org/10.1061/(asce)0733-9429(1999)125:12(1309).

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26

Hager, Willi H., Giuseppe Del Giudice, Weiming Wu, and Sam S. Y. Wang. "Movable Bed Roughness in Alluvial Rivers." Journal of Hydraulic Engineering 127, no. 7 (2001): 627–29. http://dx.doi.org/10.1061/(asce)0733-9429(2001)127:7(627).

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27

Wiberg, Patricia L., and David M. Rubin. "Bed roughness produced by saltating sediment." Journal of Geophysical Research 94, no. C4 (1989): 5011. http://dx.doi.org/10.1029/jc094ic04p05011.

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28

Gallagher, Edith L., E. B. Thornton, and T. P. Stanton. "Sand bed roughness in the nearshore." Journal of Geophysical Research: Oceans 108, no. C2 (2003): n/a. http://dx.doi.org/10.1029/2001jc001081.

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29

Rippin, David M. "Bed roughness beneath the Greenland ice sheet." Journal of Glaciology 59, no. 216 (2013): 724–32. http://dx.doi.org/10.3189/2013jog12j212.

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AbstractThe roughness of the bed beneath ice streams exerts an important control on their dynamics. Here the first in-depth analysis of roughness beneath the Greenland ice sheet is presented. Much of the interior is underlain by a smooth bed, while the margins are much rougher; this is particularly pronounced in the east where more mountainous topography dominates and fast-flow features are laterally constrained in deep narrow valleys. In contrast, fast flow in the west is much less laterally constrained and areas of high roughness are less extensive and pronounced. It is proposed that there i

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30

Nikora, V. I., T. Stoesser, S. M. Cameron, et al. "Friction factor decomposition for rough-wall flows: theoretical background and application to open-channel flows." Journal of Fluid Mechanics 872 (June 13, 2019): 626–64. http://dx.doi.org/10.1017/jfm.2019.344.

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A theoretically based relationship for the Darcy–Weisbach friction factor $f$ for rough-bed open-channel flows is derived and discussed. The derivation procedure is based on the double averaging (in time and space) of the Navier–Stokes equation followed by repeated integration across the flow. The obtained relationship explicitly shows that the friction factor can be split into at least five additive components, due to: (i) viscous stress; (ii) turbulent stress; (iii) dispersive stress (which in turn can be subdivided into two parts, due to bed roughness and secondary currents); (iv) flow unst

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31

Akutina, Yulia, Frédéric Moulin, Maxime Rouzes, and Olivier Eiff. "Flow structures in a shallow channel with lateral bed-roughness variation." E3S Web of Conferences 40 (2018): 02051. http://dx.doi.org/10.1051/e3sconf/20184002051.

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Highly heterogeneous floodplains can give rise to secondary flow structures responsible for the bulk of lateral momentum exchange. Quantifying the redistribution of momentum is required to predict lateral profiles of flow velocity and the associated water level in a river. In the work herein, we focus on studying secondary flow structures and the momentum redistribution associated with a lateral bed-roughness variation in a channel with low relative submergence of the roughness elements, h=k = 3, 2 and 1.5, where h is the flow depth and k is the roughness height. A series of laboratory experim

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32

Penna, Nadia, Francesco Coscarella, Antonino D’Ippolito, and Roberto Gaudio. "Bed Roughness Effects on the Turbulence Characteristics of Flows through Emergent Rigid Vegetation." Water 12, no. 9 (2020): 2401. http://dx.doi.org/10.3390/w12092401.

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During floods, the riparian vegetation in a watercourse significantly changes the velocity distribution and the turbulence structures of the flow. However, a certain influence on them is always exerted by the bed sediments. The aim of the present work is to study the bed roughness effects on the turbulence characteristics in an open-channel flow with rigid and emergent vegetation. Toward this end, an experimental campaign was conducted and consisted of three runs with different bed roughness conditions. The study is based on the analysis of the velocity, Reynolds shear stress, and viscous stre

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33

Ratul, Das, and Nizar Sinan. "Influence of bed roughness on near-bed turbulent flow characteristics." International Journal of Water Resources and Environmental Engineering 12, no. 3 (2020): 47–56. http://dx.doi.org/10.5897/ijwree2015.0624.

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34

Hoobi, Raad, and Ayad Saoud Najem. "Study the Affecting Factors on Free overfall Flow and Bed Roughness in Semi-Circular Channels by Artificial Neural Network." Tikrit Journal of Engineering Sciences 29, no. 4 (2022): 69–78. http://dx.doi.org/10.25130/tjes.29.4.8.

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One of the significant problems facing the water resource engineer is calculating the coefficient of roughness for subsequent design calculations of the discharge amount of a channel or river. In this study, experiments were conducted in a semi-circular, straight channel to investigate the factors affecting bed roughness and flow discharge using Artificial Neural Network (ANN). For this purpose, three semi-circular channel models with free overfall were constructed and installed in a 6-meter-long laboratory flume. The length of these models was 2.50 m with three different diameters (D= 150, 18

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35

Cooper, Michael A., Thomas M. Jordan, Dustin M. Schroeder, Martin J. Siegert, Christopher N. Williams, and Jonathan L. Bamber. "Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology." Cryosphere 13, no. 11 (2019): 3093–115. http://dx.doi.org/10.5194/tc-13-3093-2019.

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Abstract. The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained both in its bulk properties, for example geology, the presence of sediment, and the presence of water, and interfacial conditions, such as roughness and bed rheology. There is, therefore, limited understanding of how spatially heterogeneous subglacial properties relate to ice-sheet motion. Here, via analysis of 2 decades of radio-echo sounding data, we present a new systematic analysis of subglacial roughness beneath the GrIS. We use two independent methods to quantify subglacial roughness: first, the

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36

Nielsen, Peter, and Paul A. Guard. "VERTICAL SCALES AND SHEAR STRESSES IN WAVE BOUNDARY LAYERS OVER MOVABLE BEDS." Coastal Engineering Proceedings 1, no. 32 (2011): 1. http://dx.doi.org/10.9753/icce.v32.sediment.1.

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Unified scaling rules are provided for smooth and rough wave boundary layers. It is shown that the rough equivalent of the smooth, or viscous, vertical scale , the Stokes’ length, is a function of r, the Nikuradse roughness and A, the near-bed semi excursion of the wave motion. Realizing this equivalence of viscous and rough scales a unified description in the style of Colebrook’s (1939) formulae for steady flow friction can be devised based on the unified vertical scale. That is, unified smooth and rough wave friction factor formulae can be used with adequate accuracy. A general procedure is

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37

Kee, Choong Pei, Deepak T. J, and Raman Bai. "Determining Coefficient of Discharge and Coefficient of Roughness for Short Grass Bed and Concrete Bed." International Journal of Trend in Scientific Research and Development Special Issue, Special Issue-ICAEIT2017 (2018): 23–33. http://dx.doi.org/10.31142/ijtsrd19119.

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38

Nardone, Paride, and Katinka Koll. "Velocity field and drag force measurements of a cube and a hemisphere mounted on an artificial bed surface roughness." E3S Web of Conferences 40 (2018): 05022. http://dx.doi.org/10.1051/e3sconf/20184005022.

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Quantification of the resistance in complex roughness situations, when both bed surface and form roughnesses contribute to the total resistance, as well as partitioning of the two contributions is still unsolved. Studies about form resistance of single elements focused on obstacles mounted on smooth bed surfaces, and only few considered a rough bed surface. In order to define an approach for shear stress partitioning in open channel flows, the effect of flow conditions, the geometrical characteristics of the obstacle, and the effect of the bed surface need to be studied. This paper contributes

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39

Zwolenik, Monika, and Bogusław Michalec. "Effect of water surface slope and friction slope on the value of the estimated Manning’s roughness coefficient in gravel-bed streams." Journal of Hydrology and Hydromechanics 71, no. 1 (2023): 80–90. http://dx.doi.org/10.2478/johh-2022-0041.

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Abstract The aim of the study was to assess the possibility of using the empirical formulas to determine the roughness coefficient in gravel-bed streams, the bed slopes of which range from 0.006 to 0.047. Another aim was to determine the impact of taking into account the conditions of non-uniform flow on the application of these formulas and to develop the correlation relationships between the roughness coefficient and water surface slope and also between the roughness coefficient and friction slope in order to estimate the roughness coefficient n in gravel-bed streams. The studies were conduc

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Berends, Constantijn J., Roderik S. W. van de Wal, Tim van den Akker, and William H. Lipscomb. "Compensating errors in inversions for subglacial bed roughness: same steady state, different dynamic response." Cryosphere 17, no. 4 (2023): 1585–600. http://dx.doi.org/10.5194/tc-17-1585-2023.

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Abstract. Subglacial bed roughness is one of the main factors controlling the rate of future Antarctic ice-sheet retreat and also one of the most uncertain. A common technique to constrain the bed roughness using ice-sheet models is basal inversion, tuning the roughness to reproduce the observed present-day ice-sheet geometry and/or surface velocity. However, many other factors affecting ice-sheet evolution, such as the englacial temperature and viscosity, the surface and basal mass balance, and the subglacial topography, also contain substantial uncertainties. Using a basal inversion techniqu

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41

Alwan, Iman A., and Riyadh Z. Azzubaidi. "Investigations on Large-Scale Geometric Roughness Elements in Open Channels with Different Heights." Association of Arab Universities Journal of Engineering Sciences 28, no. 1 (2021): 07–14. http://dx.doi.org/10.33261/jaaru.2021.28.1.002.

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Large-scale geometric roughness elements is one of the solutions that is used to protect openchannels from erosion. It is use to change the hydraulic characteristics of the flow. It may be concrete blocksor large stone placed at the bed of the channel to impose more resistance in the bed. The height of theseroughness elements is an important parameter that can affect the hydraulic characteristics of the flow. Usinga series of tests of T-shape roughness elements at three different heights, 3, 4.5, and 6cm, arranged in thefully rough configuration in order to investigate the velocity distributio

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42

Irzooki, Raad, and Safa Hasan. "Characteristics of flow over the free overfall of triangular channel." MATEC Web of Conferences 162 (2018): 03006. http://dx.doi.org/10.1051/matecconf/201816203006.

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In the present paper, the effects of side slopes, bed slopes and bed roughness on the flow over free overfalls in triangular channels have been studied experimentally. For this purpose, three models of triangular channels with free overfalls have been constructed and fixed in a 6m length laboratory flume. These three models had length of 244cm with different values of side slopes (Z) (0.8(H):1(V), 1:1 and 1.33:1). Each one of these models had four different bed slopes (S) (0, 0.0041, 0.0082 and 0.0123). For each bed slope, the bed was roughened with three particle sizes of sand (ds) (1.18mm, 2

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43

Matoušek, Václav, and Jan Krupička. "On equivalent roughness of mobile bed at high shear stress." Journal of Hydrology and Hydromechanics 57, no. 3 (2009): 191–99. http://dx.doi.org/10.2478/v10098-009-0018-9.

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On equivalent roughness of mobile bed at high shear stressThe friction conditions at the top of a mobile bed are discussed for flows in the upper-plane-bed regime, i.e. for the flows with values of the bed Shields parameter larger than approximately 0.6. A special attention is devoted to flows of the bed Shields parameter bigger than 2. Experimental data for flows at high bed shear are collected from literature and new data are added from own measurements of flows of a 1.36-mm sand slurry in the 100-mm pipe loop of the Institute of Hydrodynamics. The database represents flows of very different

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44

Bicudo, J. R., and M. F. Giorgetti. "The Effect of Strip Bed Roughness on the Reaeration Rate Coefficient." Water Science and Technology 23, no. 10-12 (1991): 1929–39. http://dx.doi.org/10.2166/wst.1991.0649.

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Measurements are presented for the rate of atmospheric reaeration in open-channel flow under different conditions of depth and bed roughness. A 2k factorial design was employed for the estimation of both depth and bed resistance factor effects upon stream reaeration. Consistent results indicated that stream reaeration is primarily controlled by water shear, but that different modes of instability generated by a combination of depth and strip roughness levels might prevail for different boundary roughness conditions, and as a consequence, differently affect the reaeration coefficient.

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45

Zhou, Yin-jun, Jin-you Lu, Li Chen, and Jie Ren. "Bed roughness adjustments determined from fractal measurements of river-bed morphology." Journal of Hydrodynamics 30, no. 5 (2018): 882–89. http://dx.doi.org/10.1007/s42241-018-0101-y.

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46

Cai, Yiheng, Fuxing Wan, Shinan Lang, Xiangbin Cui, and Zijun Yao. "Multi-Branch Deep Neural Network for Bed Topography of Antarctica Super-Resolution: Reasonable Integration of Multiple Remote Sensing Data." Remote Sensing 15, no. 5 (2023): 1359. http://dx.doi.org/10.3390/rs15051359.

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Bed topography and roughness play important roles in numerous ice-sheet analyses. Although the coverage of ice-penetrating radar measurements has vastly increased over recent decades, significant data gaps remain in certain areas of subglacial topography and need interpolation. However, the bed topography generated by interpolation such as kriging and mass conservation is generally smooth at small scales, lacking topographic features important for sub-kilometer roughness. DeepBedMap, a deep learning method combined with multiple surface observation inputs, can generate high-resolution (250 m)

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47

Daneshfaraz, Rasoul, Amir Ghaderi, Aliakbar Akhtari, and Silvia Di Francesco. "On the Effect of Block Roughness in Ogee Spillways with Flip Buckets." Fluids 5, no. 4 (2020): 182. http://dx.doi.org/10.3390/fluids5040182.

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In this study, the effect of the presence of bed-block roughness in an ogee spillway on energy dissipation and jet length is investigated. A series of experimental and numerical tests were conducted using an ogee spillway with block roughness on the bed without a flip bucket and with a flip bucket at different take-off angles (32 °C and 52 °C). To model the free-flow surface, the volume-of-fluid (VOF) method and turbulence model from RNG k–ε were used. Results indicated that the numerical model is fairly capable of simulating a free-flow surface over an ogee spillway; using block roughness on

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48

Zhou, Jie, Beibei Han, and Haifeng Wang. "Surface Roughness Characteristics and Their Influence on Wind Erosion and Sand Movement." Atmosphere 16, no. 4 (2025): 443. https://doi.org/10.3390/atmos16040443.

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Wind erosion significantly threatens sustainable development in desert regions, causing severe soil degradation. Investigating the influence of roughness elements on wind–sand interactions is vital for devising effective wind erosion control strategies. This study examined the effects of smooth and porous surface roughness elements on wind–sand activity and the wind erosion rate of a sand bed surface. Wind tunnel experiments were conducted with 10% coverage of these elements on the sand bed surface under varying wind speeds. Results showed that porous-surfaced roughness elements were less resp

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49

Smart, Graeme, Jochen Aberle, Maurice Duncan, and Jeremy Walsh. "Measurement and analysis of alluvial bed roughness." Journal of Hydraulic Research 42, no. 3 (2004): 227–37. http://dx.doi.org/10.1080/00221686.2004.9728388.

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Bertin, Stephane, Jane Groom, and Heide Friedrich. "Isolating roughness scales of gravel-bed patches." Water Resources Research 53, no. 8 (2017): 6841–56. http://dx.doi.org/10.1002/2016wr020205.

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