def problem_1(container, special_particles, **extra_params):
"""Create a triangular (hex) lattice with N = 64 particles. The dimensions of the lattice should be Lx and Ly = sqrt(3)/2*Lx
"""
N = 8 # this is 8x8 = 64 particles
Lx = extra_params.get('Lx', None)
Lx = Lx or container.bounds[0] # error here would indicate bounds haven't been set
Ly = math.sqrt(3)/2 * Lx
container.bounds = (Lx, Ly)
dx = Lx / float(N)
dy = Ly / float(N)
moldyn.add_triangle_lattice(container, N, N, dx, dy)
return container, special_particles
def hourglass(funnel_width, hole_width, d_angle_from_horizon_to_wall, dist_between_anchors, diam, grain_height, **kwargs_ignore):
""" Make a container with "anchor" particles set up as walls of an hourglass
:param kwargs_ignore: ignored extra args so you can use an exploded dictionary (**myargdict) for arg input
:param diam: diameter of each grain and anchor
:returns: container, y_funnel_bottom
"""
# Do calculations for funnel
r_angle = math.radians(d_angle_from_horizon_to_wall)
tan_over_2 = math.tan(r_angle)/2.0
height_funnel = funnel_width * tan_over_2
hole_width += diam # trick to allow space so bottom anchors don't overlap, e.g. so a zero-width hole actually places anchors with their borders touching instead of with their centers touching
height_hole = hole_width * tan_over_2
xdist = dist_between_anchors * math.cos(r_angle)
ydist = dist_between_anchors * math.sin(r_angle)
# Centers of wall particles
def get_anchor_centers(xstart, xend, xdist, left_side=True):
# np.arange doesn't let you go from a greater to a lesser value, so invert twice to get that behavior
if xstart > xend:
dx = (xstart - xend)
## xs = -np.arange(-xstart, -xend, xdist)
else:
dx = (xend - xstart)
## xs = np.arange(xstart, xend, xdist)
num_anchors = math.ceil(dx / xdist)
xs = np.linspace(xstart, xend, num_anchors)
return xs
# Right wall equation: goes from ( (wf + wh)/2, hh - hf ) to (wf, 0)
#m = (height_funnel - height_hole) / (funnel_width - (funnel_width + hole_width)/2.0)
extra_funnel_extension = 0 # messes up hole alignment
y_funnel_bottom = height_hole - height_funnel # y is negative
xrs = get_anchor_centers((funnel_width + hole_width)/2.0, funnel_width + extra_funnel_extension, xdist)
yrs = get_anchor_centers(y_funnel_bottom, extra_funnel_extension, ydist, False)
# Left wall goes from (0, 0) to ( (wf - wh)/2, hh - hf)
xls = get_anchor_centers(-extra_funnel_extension, (funnel_width - hole_width)/2.0, xdist)
yls = get_anchor_centers(extra_funnel_extension, y_funnel_bottom, ydist, False)
# Place anchors
# NOTE: the order of adding matters when plotting anchor forces, so try to add from left to right
c = Container()
# Make side walls/anchors
# NOTE: The anchors at y = 0 are placed by other code
wall_ys = np.arange(diam, grain_height + diam, diam)
for y in reversed(wall_ys): # high to low
c.add_particle([0, y])
def add_anchors(xs, ys):
for x, y in zip(xs, ys):
c.add_particle([x, y])
add_anchors(xls, yls)
add_anchors(xrs, yrs)
# KLUDGE repeating sucks, but I want the anchor ixs in the right order
for y in wall_ys: # low to high
c.add_particle([funnel_width, y])
anchor_ixs = range(c.num_particles)
# Finally, add sand
moldyn.add_triangle_lattice(c,
(diam, funnel_width-diam),
(diam, grain_height),
diam, diam)
return c, y_funnel_bottom, anchor_ixs
