Normal Distribution Nail Board Experiment
Script and Data Download: Nail Coordinates: init_xyr.dat VBOX Script: normal_distribution.pynormal_distribution.py)
This is a normal distribution nail board experiment completed based on discrete element numerical simulation.
In the figure below, each gray dot represents a nail, and the distances between them are equal. The horizontal position of each nail in the upper layer is precisely located between the two nails in the lower layer. A certain number of small balls, with a diameter smaller than the distance between two nails, are generated above the nail area and dropped down at the entrance. The small balls propagate downward in the nail board area until they fall into the bottom board. A large number of identical small balls continuously drop from the entrance, and as long as the number of balls is sufficiently large, they will form an approximate normal density function pattern on the bottom board (i.e., high in the middle, low at both ends, resembling a bell shape).
Dynamic Diagram
Static Process
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VBOX Script Source Code normal_distribution.py
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# title:正态分布钉板实验
# date:2021-02-26
# authors:钟军 李长圣
# E-mail:sheng0619@163.com
# more info, see www.geovbox.com
#######################################
#程序初始化
LOAD init_xyr.dat
PROP GROUP _ball
PROP COLOR lg RANGE GROUP _ball
#颗粒设为球，计算颗粒体积用4/3*pi*r^3计算
SET disk off
#设置研究范围
BOX left 0.0 right 11000.0 bottom 0.0 height 21000.0 kn=0e10 ks=0e10 fric 0.00
#设置挡板墙，这里模型采用hertz接触模型，挡板墙的kn ks无效，计算时取颗粒的参数
WALL ID 0, NODES ( 1000.0 , 19000.0 ) ( 5260.0 , 16000.0 ), kn=0e10 ks=0e10 fric 0.3 COLOR black
WALL ID 1, NODES ( 5740.0 , 16000.0 ) ( 10000.0, 19000.0 ), kn=0e10 ks=0e10 fric 0.3 COLOR black
#限制运动
FIX x y spin RANGE group _ball
#底部挡板钉
GLINE RAD=40 P1 ( 1000.0 1000.0 ) P2 ( 10000.0 1000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 1000.0 1000.0 ) P2 ( 1000.0 21000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 2000.0 1000.0 ) P2 ( 2000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 3000.0 1000.0 ) P2 ( 3000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 4000.0 1000.0 ) P2 ( 4000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 5000.0 1000.0 ) P2 ( 5000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 6000.0 1000.0 ) P2 ( 6000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 7000.0 1000.0 ) P2 ( 7000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 8000.0 1000.0 ) P2 ( 8000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 9000.0 1000.0 ) P2 ( 9000.0 5000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 10000.0 1000.0 ) P2 ( 10000.0 21000.0 ), color=black GROUP=bom
GLINE RAD=40 P1 ( 1000.0 21000.0 ) P2 ( 10000.0 21000.0 ), color=black GROUP=bom
FIX x y spin RANGE group bom
#在矩形范围内生成颗粒
GEN NUM 35000 rad discrete 60.0 60.0, x (2800.0, 8200.0), y ( 18000.0, 21000.0), COLOR blue GROUP _ball
PROP density 2.5e3, fric 0.3, shear 2.9e9, poiss 0.2, damp 0.4, hertz
#设置时间步及重力加速度
SET DT 5e-2, GRAVITY 0.0, -9.8
#设置每1000步保存一次vtk格式的计算结果
SET vtk 300
#设置每1000步保存一次ps格式的计算结果
SET ps 300
#设置每1000步保存一次dat格式的计算结果
SET print 300
#计算5000步
CYC 25000
#停止
STOP
Translator: Zhu Suqin