pasir 0.0.4

granular-based simulation and related systems

pasir

granular-based simulation and related systems

install

pip install pasir

instantiation

grain

Syntax

Grain([id[, m[, d[, q[, b]]]]])

• id: identification in string, e.g. 0092, default 0000.
• m : mass, e.g. 0.5, default 0.
• d : diameter, e.g. 1.2, default 0.
• q : charge, e.g. -0.1, default 0.
• b : artificial property, e.g. 5.3, default 0.

Code

g = Grain()
g.r = Vect3(1, 2, 3)
g.color = Color2('#0f0', '#ff0')
print(g)

Output

{
  "id": "0000",
  "m": 0,
  "d": 0,
  "q": 0,
  "b": 0,
  "color": { "stroke": "#0f0", "fill": "#ff0" },
  "r": { "x": 1, "y": 2, "z": 3 },
  "v": { "x": 0, "y": 0, "z": 0 },
  "a": { "x": 0, "y": 0, "z": 0 }
}

gravitational2

Syntax

Gravitational2([constant])

• constant: Gravitational constant.

Code

from pasir.butiran.color2 import Color2
from pasir.butiran.math.vect3 import Vect3
from pasir.butiran.grain import Grain
from pasir.butiran.force.gravitational2 import Gravitational2

if True:
  G = 5
  gravitational = Gravitational2(constant=G)
  print(gravitational)
  
  grain1 = Grain(id="0000", m=5)
  grain1.r = Vect3(0, 0, 0)
  print(grain1)
  
  grain2 = Grain(id="0034", m=10)
  grain2.r = Vect3(3, 4, 0)
  print(grain2)
  
  fg12 = gravitational.force(grain1, grain2)
  print(fg12)
  
  fg21 = gravitational.force(grain2, grain1)
  print(fg21)

Output

{
  "constant": "5",
}
{
  "id": "0000",
  "m": 5,
  "d": 0,
  "q": 0,
  "b": 0,
  "color": { "stroke": "#000", "fill": "#fff" },
  "r": { "x": 0, "y": 0, "z": 0 },
  "v": { "x": 0, "y": 0, "z": 0 },
  "a": { "x": 0, "y": 0, "z": 0 }
}
{
  "id": "0034",
  "m": 10,
  "d": 0,
  "q": 0,
  "b": 0,
  "color": { "stroke": "#000", "fill": "#fff" },
  "r": { "x": 3, "y": 4, "z": 0 },
  "v": { "x": 0, "y": 0, "z": 0 },
  "a": { "x": 0, "y": 0, "z": 0 }
}
{ "x": 6.0, "y": 8.0, "z": -0.0 }
{ "x": -6.0, "y": -8.0, "z": -0.0 }

examples

parabolic motion

from pasir.butiran.color2 import Color2
from pasir.butiran.math.vect3 import Vect3
from pasir.butiran.grain import Grain
from pasir.butiran.force.gravitational import Gravitational

# define grain with initial position and velocity
grain = Grain(id="0002", m = 1)
grain.r = Vect3(0, 0, 0)
grain.v = Vect3(30, 40, 0)

# define gravitational field and force
g = Vect3(0, -10, 0)
gravitational = Gravitational(field=g)

import numpy as np

# define iteration
tbeg = 0
tend = 8
N = 100
dt = (tend - tbeg) / N

# define lists
data_t = []
data_x = []
data_y = []
data_vx = []
data_vy = []

# perform iteration
#print("#t x y vx vy")
print("Calculate position and velocity.")
for i in range(N + 1):
  t = i
  
  m = grain.m
  v = grain.v
  r = grain.r
  
  data_t.append(t)
  data_x.append(r.x)
  data_y.append(r.y)
  data_vx.append(v.x)
  data_vy.append(v.y)

  fg = gravitational.force(grain)
  a = fg / m
  v += a * dt
  r += v * dt
  
  grain.v = v
  grain.r = r
  
  #print(t, ' ', end='')
  #print(r.x, ' ', r.y, ' ', end='')
  #print(v.x, ' ', v.y)
  
print("Plot data.")
from matplotlib.pyplot import figure
import matplotlib.pyplot as plt

figure(figsize=(5,3.5), dpi=80)

plt.plot(data_x, data_y, c='r')
plt.xlabel('x')
plt.ylabel('y')

plt.grid()
plt.xlim([0, 240])
plt.ylim([0, 80])
plt.xticks(np.arange(0, 240+0.01, 40))
plt.yticks(np.arange(0, 80+0.01, 20))

plt.text(60, 39, "$v_x = 30$, $v_y = 40$, $m = 1$", fontsize=12)
plt.text(98, 30, "$g = -10$", fontsize=12)

print("Save figure.")
plt.savefig('parabolic_gravitational_euler.png', bbox_inches='tight')

circular motion

from butiran.color2 import Color2
from butiran.math.vect3 import Vect3
from butiran.grain import Grain
from butiran.force.magnetic import Magnetic

# define grain with initial position and velocity
grain = Grain(id="0001", m = 1, q = 1)
grain.r = Vect3(1, 0, 0)
grain.v = Vect3(0, 1, 0)

# define magnetic field and force
B = Vect3(0, 0, -1)
magnetic = Magnetic(field=B)

import numpy as np

# define iteration
tbeg = 0
tend = 2 * np.pi
N = 10000
dt = (tend - tbeg) / N

# define lists
data_t = []
data_x = []
data_y = []
data_vx = []
data_vy = []

# perform iteration
#print("#t x y vx vy")
print("Calculate position and velocity.")
for i in range(N + 1):
  t = i
  
  m = grain.m
  v = grain.v
  r = grain.r
  
  data_t.append(t)
  data_x.append(r.x)
  data_y.append(r.y)
  data_vx.append(v.x)
  data_vy.append(v.y)

  fB = magnetic.force(grain)
  a = fB / m
  v += a * dt
  r += v * dt
  
  grain.v = v
  grain.r = r
  
  #print(t, ' ', end='')
  #print(r.x, ' ', r.y, ' ', end='')
  #print(v.x, ' ', v.y)
  
print("Plot data.")
from matplotlib.pyplot import figure
import matplotlib.pyplot as plt

figure(figsize=(5,5), dpi=80)

plt.plot(data_x, data_y, c='r')
plt.xlabel('x')
plt.ylabel('y')

plt.grid()
plt.xlim([-1.5, 1.5])
plt.ylim([-1.5, 1.5])
plt.xticks(np.arange(-1.5, 1.5+0.01, 0.5))
plt.yticks(np.arange(-1.5, 1.5+0.01, 0.5))

plt.text(-0.5, 0.2, "$B = 1, m = 1, q = 1$", fontsize=12)
plt.text(-0.4, -0.05, "$\Delta t = 2 \pi \ / \ 10^4$", fontsize=12)
plt.text(-0.3, -0.3, "$T \in [0, 2\pi]$", fontsize=12)

print("Save figure.")
plt.savefig('circular_magnetic_euler.png', bbox_inches='tight')