The present study describes entrainment characteristics of bed material into debris flow, based on flume tests, numerical and dimensional analyses. Flume tests are conducted to investigate influences of bed sediment size on erosion rate by supplying debris flows having unsaturated sediment concentration over erodible beds. Experimental results show that the erosion rate decreases monotonically ...

[1] Bed load sediment particles supplied to channels by hillslopes are reduced in size by abrasion during downstream transport. The branching structure of the channel network creates a distribution of downstream travel distances to a given reach of river and thus may strongly influence the grain size distribution of the long-term bed load flux through that reach. Here we investigate this hypoth...

The local solid flow structure of gas-solid bubbling fluidized bed was investigated to identify and characterize the particle clusters. Extensive mathematical calculations were carried out using the energy-minimization multi-scale (EMMS) approach for evaluating cluster properties including the velocity, the size and the void fraction of clusters in the dense phase of the bed. The results showed...

The size and shape of the stones in dry gravel river beds are of interest in geology and river hydraulics. The topography of a bed surface can be measured by three-dimensional laser scanning. A method is described for fitting ellipsoids to the surfaces of individual stones to estimate their size, shape and orientation in the river bed. Different cost functions are evaluated and the methods are ...

We report the first measurements of friction angles for a naturally formed gravel streambed. For a given test grain size placed on a bed surface, friction angles varied from 10" to over 100'; friction angle distributions can be expressed as a function of test grain size, median bed grain size, and bed sorting parameter. Friction angles decrease with increasing grain size relative to the median ...

Size enlargement of fine powders by wet granulation involves mixing of fine particles with a binder liquid to form larger wet granules and drying them by evaporation of the binder liquid to form larger dry granules. Identification of the time for completion of granulation process is critical as further mixing of dry granules is providing extra energy for their attrition. In a batch fluidized be...

Gravel bed channels have a much greater capacity than sand bed channels to regulate the mobility of the bed surface through the formation of a surface layer of bed particles that is coarser than the particles supplied as load. The coarse surface layer affects bed mobility in two important ways. First, it reduces differences in mobility between coarser and finer particles on the bed surface by m...

abstract for investigating the effect of bed form in alluvial channels on the amount of bed load transport, a set of experiments was carried out in a tilting flume under unsteady flow conditions (hydrograph). the produced hydrographs were in triangular form with a maximum discharge of 30 to 45 lit/s/m. three size of sediment particles were used with equal to 1.5, 2.1 and 3.0mm, clear water with...

The acoustic Doppler velocimeter (ADV) has recently been suggested as a promising instrument for characterizing near-bed flows, particularly in the first 10 mm above the bed where many benthic organisms live. Flow characteristics in such settings often exhibit steep vertical gradients, however, so the reliable use of the ADV requires knowledge of the size and location of the instrument’s acoust...

Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1–5mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between graveland sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or ...