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Title: 越流水による礫群運動の3次元数値解析
Other Titles: 3D NUMERICAL ANALYSIS FOR MOVEMENTS OF GRAVEL PARTICLES DUE TO OVERFLOW
Authors: 柳生, 大輔  KAKEN_name
牛島, 省  kyouindb  KAKEN_id
鳥生, 大祐  KAKEN_name
Author's alias: YAGYU, Daisuke
USHIJIMA, Satoru
TORIU, Daisuke
Keywords: fluid-solid interaction
multiphase model
parallel computation
free-surface flow
gravel particle
Issue Date: 2016
Publisher: 土木学会
Journal title: 土木学会論文集A2 (応用力学) = Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics)
Volume: 72
Issue: 2
Start page: l_295
End page: l_302
Abstract: 堰を越流して落下した水流により14, 400個の礫群が運動し, ある堆積形状となる過程の数値計算を行った. 計算では, 3次元固気液多相場の解法(MICS)を利用し, 礫群の運動と越流水の力学的な相互作用を考慮した並列計算を行った. 1個の礫を121個の四面体要素で表し, 気液相の運動方程式から得られた圧力項と粘性項を利用して礫に働く流体力を求める. 礫どうしの接触力は, 礫モデル内部に任意に配置した接触判定球を用いて, DEMにより算出する. 224並列処理により, 逐次計算に対して約50倍の計算速度となった. 計算結果から, 堰を越流した水流により礫が巻き上げられる挙動が再現され, 越流停止後は礫群は洗掘された配置となった. 越流量を増加させると, 最大洗掘深および洗掘範囲が増加するという既往実験と同様の傾向が得られた.
In this study, the local scour behind the weir due to overflows was calculated using three-dimensional multiphase numerical model (MICS). In this method, the shape of a gravel particle is represented by multiple tetrahedron elements, and collisions between gravel particles are treated by the contacts of the multiple collision detection spheres placed inside of the gravel particle. Fluid forces acting on the gravel particle are calculated from the pressure-gradient and viscous terms in the momentum equations for multiphase fields. As a result of the numerical experiments, movements of 14,400 gravel particles due to the overflow were predicted and local scour arose behind the weir. In addition, the scour depth and area become larger when the flow rate is large.
Rights: © 公益社団法人 土木学会/Japan Society of Civil Engineers
URI: http://hdl.handle.net/2433/229522
DOI(Published Version): 10.2208/jscejam.72.I_295
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