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Volume 13, Issue 1
Displaying 1-5 of 5 articles from this issue
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Tetsuro TSUJIMOTO1999 Volume 13 Issue 1 Pages 3-11
Published: March 15, 1999
Released on J-STAGE: February 22, 2011
JOURNAL FREE ACCESSRiver restoration is a current topic in river engineering, where multiple functions of rivers such as the safety against flood, water resources utilization, amenity of human life and ecological system conservation are desired to be satisfied simultaneously. For this purpose, the technique to control the interactions among flow, sediment transport, vegetation and river morphology is strongly required. It is supported by fluvial hydraulics, hydraulics of flow with vegetation and habitat hydraulics, and the research from the view point of multiphase-flow study is expected to contribute them. In this paper, the new understanding of river restoration is explained by using the concept of “river landscape”, and it is discussed how the recent development of study on fluvial hydraulics related to riparian vegetation contributes to it. Since the mechanics of sediment transport and modeling of flow with vegetation are reviewed by the other authors of this volume, the studies on fractional transport of graded sediment with sorting process and the riarian morphology related to vegetation growth are focussed on herein.View full abstractDownload PDF (5399K) -
Syunsuke IKEDA, Yuji TODA1999 Volume 13 Issue 1 Pages 12-21
Published: March 15, 1999
Released on J-STAGE: February 22, 2011
JOURNAL FREE ACCESSThe turbulent flow structure and the transports of heat and substances in and above vegetation layer were studied by the field observation and the laboratory test.At the field observation, fluctuations of wind velocity, temperature, carbon dioxide and vapor were measured by using sophisticated devices.The vortices were observed to be composed of strong sweep and weak ejection, and the temporal variation of sensible heat showed ramp pattern. Transports of heat, fluid momentum and vapor are found to be closely correlated with organized vortices. Twodimensional horizontal structure of vortices was detected by thermography. The instantaneous three-dimensional structure of the organized vortex was measured by employing PIV and MASCON model in the laboratory flume.The shape of the organized vortex is elliptical, and the vortex is inclined downward toward the front, a profile of which is effective in yielding Reynolds stress.View full abstractDownload PDF (14086K) -
Yoshihiko SHIMIZU1999 Volume 13 Issue 1 Pages 22-31
Published: March 15, 1999
Released on J-STAGE: February 22, 2011
JOURNAL FREE ACCESSRecently hydraulics in open-channel flow with vegetated zone becomes important increasingly for river restoration. Vegetated zone can be regarded as a kind of porous region and momentum sink due to the form drag. Flows inside and outside vegetation zones bring about strong shear layer and cause momentum exchange and additional resistance between them. In this paper, the recent studies of numerical calculation on fully developed turbulent flow in open-channel with vegetation zone are outlined:(1) modeling of vegetation for river hydraulics, (2) flow over vegetation, (3) compound channel flow with vegetation, (4) flow with vegetation zone.View full abstractDownload PDF (7643K) -
Yasuo NIHEI, Kazuo NADAOKA1999 Volume 13 Issue 1 Pages 32-41
Published: March 15, 1999
Released on J-STAGE: February 22, 2011
JOURNAL FREE ACCESSTo realize LES for a multiphase turbulent flow with a quite large number of particles, the authors have recently developed a new multiphase LES, named “GAL-LES model”. The GAL (Grid- Averaged Lagrangian) model is based on a grid-averaging operation for a Lagrangian-type equation of a particle motion and reallocation procedure of a particle cloud with its centroid movement to each grid. The GAL-LES model has been applied to a particle plume and a sheet-flow-type sediment transport, showing that the present model is found to simulate the essential features of the large-eddy structure and gives good agreements with the existing experimental data.View full abstractDownload PDF (8429K) -
Hitoshi GOTOH1999 Volume 13 Issue 1 Pages 42-51
Published: March 15, 1999
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSThe development process of the computational mechanics of sediment transport is reviewed briefly. First, the importance of the description of the irregular motion of the sediment particle, which consists the essential part of the non-equilibrium sediment transport process, is explained. Secondary, the multiphase flow model for the modeling of the flow/sediment interaction is reviewed. As the increase of the sediment concentration, not only the flow/sediment interaction but also the particle/particle interaction, or interparticle collision, play the significant role. The application of the granular material model of the interparticle collision to the sediment transport process is also reviewed.Finally the unresolved problems and the prospects of the computational mechanics of sediment transport are discussed briefly.View full abstractDownload PDF (1476K)
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