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djsilva99 merged 2 commits into from
Mar 31, 2026
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refactor: vectorize explicit stencils, extract shared latent heat in 1D solvers #73

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e62c758
refactor: vectorize 1D explicit solvers, extract shared latent heat
Mar 23, 2026
2e183e0
test: add phase transition test for water at 273K
Mar 31, 2026
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52 changes: 52 additions & 0 deletions heatrapy/dimension_1/solvers/_latent_heat.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,52 @@
"""Shared latent heat computation for 1D solvers."""

import copy


def apply_latent_heat(nx, obj):
"""Apply latent heat corrections to computed temperatures.

Handles phase transitions by absorbing/releasing energy when the
temperature crosses a transition threshold.

Parameters
----------
nx : list
New temperatures for each grid point (modified in place).
obj : Object
Thermal object with current state.

Returns
-------
lheat : list
Updated latent heat accumulation state.

"""
lheat = copy.copy(obj.lheat)
for i in range(1, obj.num_points - 1):
j = 0
for lh in obj.latent_heat[i]:
temper = obj.temperature[i][0]
# heating: crossing transition from below
if nx[i] > lh[0] and temper <= lh[0] and lheat[i][j][1] != lh[1]:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - temper)
if en + lheat[i][j][1] >= lh[1]:
lheat[i][j][1] = lh[1]
energy_temp = lheat[i][j][1] + en - lh[1]
nx[i] = temper + energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = temper
# cooling: crossing transition from above
if nx[i] < lh[0] and temper >= lh[0] and lheat[i][j][1] != 0:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - temper)
if en + lheat[i][j][1] <= 0.:
lheat[i][j][1] = 0.
energy_temp = (en + lheat[i][j][1])
nx[i] = temper + energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = temper
j += 1

return lheat
105 changes: 39 additions & 66 deletions heatrapy/dimension_1/solvers/explicit_general.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,9 @@

"""

import copy
import numpy as np

from ._latent_heat import apply_latent_heat


def explicit_general(obj):
Expand All @@ -14,75 +16,46 @@ def explicit_general(obj):
conductivity.

"""
x = copy.deepcopy(obj.temperature)

# computes
for i in range(1, obj.num_points - 1):

alpha = obj.dt * \
obj.k[i] / (obj.rho[i] * obj.Cp[i] *
obj.dx * obj.dx)
beta = obj.dt / (obj.rho[i] * obj.Cp[i])

t_new = ((1 + beta * obj.Q[i]) * obj.temperature[i][0] +
alpha * (obj.temperature[i - 1][0] - 2 *
obj.temperature[i][0] + obj.temperature[i + 1][0]) +
beta * (obj.Q0[i] - obj.Q[i] * obj.amb_temperature))
x[i][1] = t_new

# left boundary for next time step
n = obj.num_points
s = slice(1, n - 1)

# extract current temperatures and material properties as arrays
T = np.array([obj.temperature[i][0] for i in range(n)], dtype=float)
k = np.array([obj.k[i] if obj.k[i] is not None else 0.0 for i in range(n)])
rho = np.array([obj.rho[i] if obj.rho[i] is not None else 1.0
for i in range(n)])
Cp = np.array([obj.Cp[i] if obj.Cp[i] is not None else 1.0
for i in range(n)])
Q = np.array([obj.Q[i] if obj.Q[i] is not None else 0.0
for i in range(n)])
Q0 = np.array([obj.Q0[i] if obj.Q0[i] is not None else 0.0
for i in range(n)])

# vectorized FDM stencil for interior points
alpha = obj.dt * k[s] / (rho[s] * Cp[s] * obj.dx * obj.dx)
beta = obj.dt / (rho[s] * Cp[s])

nx = T.copy()
nx[s] = ((1 + beta * Q[s]) * T[s] +
alpha * (T[0:n-2] - 2 * T[s] + T[2:n]) +
beta * (Q0[s] - Q[s] * obj.amb_temperature))

# boundaries
if obj.boundaries[0] == 0:
x[0][1] = obj.temperature[1][1]
nx[0] = T[1]
else:
x[0][1] = obj.boundaries[0]
nx[0] = obj.boundaries[0]

# right boundary for next time step
if obj.boundaries[1] == 0:
x[obj.num_points - 1][1] = obj.temperature[obj.num_points - 2][1]
nx[n - 1] = T[n - 2]
else:
x[obj.num_points - 1][1] = obj.boundaries[1]

# updates temperature for next iteration
for i in range(0, obj.num_points):
x[i][0] = x[i][1]

nx = []
for i in range(len(x)):
nx.append(x[i][0])

# latent heat
lheat = copy.copy(obj.lheat)
for i in range(1, obj.num_points - 1):
j = 0
for lh in obj.latent_heat[i]:
temper = obj.temperature[i][0]
if nx[i] > lh[0] and temper <= lh[0] and lheat[i][j][1] != lh[1]:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - obj.temperature[i][0])
if en + lheat[i][j][1] >= lh[1]:
lheat[i][j][1] = lh[1]
energy_temp = lheat[i][j][1] + en - lh[1]
nx[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = obj.temperature[i][0]
if nx[i] < lh[0] and temper >= lh[0] and lheat[i][j][1] != 0:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - obj.temperature[i][0])
if en + lheat[i][j][1] <= 0.:
lheat[i][j][1] = 0.
energy_temp = (en + lheat[i][j][1])
nx[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = obj.temperature[i][0]
j += 1

y = copy.deepcopy(obj.temperature)

# updates the temperature list
for i in range(obj.num_points):
y[i][1] = nx[i]
y[i][0] = nx[i]
nx[n - 1] = obj.boundaries[1]

# latent heat (per-element, branching logic)
nx_list = nx.tolist()
lheat = apply_latent_heat(nx_list, obj)

# pack into [current, next] pairs expected by the caller
y = [[nx_list[i], nx_list[i]] for i in range(n)]

return y, lheat
107 changes: 41 additions & 66 deletions heatrapy/dimension_1/solvers/explicit_k.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,9 @@

"""

import copy
import numpy as np

from ._latent_heat import apply_latent_heat


def explicit_k(obj):
Expand All @@ -14,75 +16,48 @@ def explicit_k(obj):
conductivity.

"""
x = copy.deepcopy(obj.temperature)

# computes
for i in range(1, obj.num_points - 1):
eta = obj.dt / (2. * obj.rho[i] * obj.Cp[i] * obj.dx * obj.dx)
beta = obj.dt / (obj.rho[i] * obj.Cp[i])

t_new = ((1 + beta * obj.Q[i]) * obj.temperature[i][0] +
eta * ((obj.k[i + 1] + obj.k[i]) * obj.temperature[i + 1][0] -
(obj.k[i - 1] + obj.k[i + 1] + 2 * obj.k[i]) *
obj.temperature[i][0] + (obj.k[i - 1] + obj.k[i]) *
obj.temperature[i - 1][0]) +
beta * (obj.Q0[i] - obj.Q[i] * obj.amb_temperature))

x[i][1] = t_new

# left boundary for next time step
n = obj.num_points
s = slice(1, n - 1)

# extract current temperatures and material properties as arrays
T = np.array([obj.temperature[i][0] for i in range(n)], dtype=float)
k = np.array([obj.k[i] if obj.k[i] is not None else 0.0 for i in range(n)])
rho = np.array([obj.rho[i] if obj.rho[i] is not None else 1.0
for i in range(n)])
Cp = np.array([obj.Cp[i] if obj.Cp[i] is not None else 1.0
for i in range(n)])
Q = np.array([obj.Q[i] if obj.Q[i] is not None else 0.0
for i in range(n)])
Q0 = np.array([obj.Q0[i] if obj.Q0[i] is not None else 0.0
for i in range(n)])

# vectorized FDM stencil for interior points (k varies with x)
eta = obj.dt / (2.0 * rho[s] * Cp[s] * obj.dx * obj.dx)
beta = obj.dt / (rho[s] * Cp[s])

nx = T.copy()
nx[s] = ((1 + beta * Q[s]) * T[s] +
eta * ((k[2:n] + k[s]) * T[2:n] -
(k[0:n-2] + k[2:n] + 2 * k[s]) * T[s] +
(k[0:n-2] + k[s]) * T[0:n-2]) +
beta * (Q0[s] - Q[s] * obj.amb_temperature))

# boundaries
if obj.boundaries[0] == 0:
x[0][1] = obj.temperature[1][1]
nx[0] = T[1]
else:
x[0][1] = obj.boundaries[0]
nx[0] = obj.boundaries[0]

# right boundary for next time step
if obj.boundaries[1] == 0:
x[obj.num_points - 1][1] = obj.temperature[obj.num_points - 2][1]
nx[n - 1] = T[n - 2]
else:
x[obj.num_points - 1][1] = obj.boundaries[1]

# updates temperature for next iteration
for i in range(0, obj.num_points):
x[i][0] = x[i][1]

nx = []
for i in range(len(x)):
nx.append(x[i][0])

# latent heat
lheat = copy.copy(obj.lheat)
for i in range(1, obj.num_points - 1):
j = 0
for lh in obj.latent_heat[i]:
temper = obj.temperature[i][0]
if nx[i] > lh[0] and temper <= lh[0] and lheat[i][j][1] != lh[1]:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - obj.temperature[i][0])
if en + lheat[i][j][1] >= lh[1]:
lheat[i][j][1] = lh[1]
energy_temp = lheat[i][j][1] + en - lh[1]
nx[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = obj.temperature[i][0]
if nx[i] < lh[0] and temper >= lh[0] and lheat[i][j][1] != 0:
en = obj.Cp[i] * obj.rho[i] * (nx[i] - obj.temperature[i][0])
if en + lheat[i][j][1] <= 0.:
lheat[i][j][1] = 0.
energy_temp = (en + lheat[i][j][1])
nx[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
nx[i] = obj.temperature[i][0]
j += 1

y = copy.deepcopy(obj.temperature)

# updates the temperature list
for i in range(obj.num_points):
y[i][1] = nx[i]
y[i][0] = nx[i]
nx[n - 1] = obj.boundaries[1]

# latent heat (per-element, branching logic)
nx_list = nx.tolist()
lheat = apply_latent_heat(nx_list, obj)

# pack into [current, next] pairs expected by the caller
y = [[nx_list[i], nx_list[i]] for i in range(n)]

return y, lheat
56 changes: 15 additions & 41 deletions heatrapy/dimension_1/solvers/implicit_general.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@
"""

import numpy as np
import copy

from ._latent_heat import apply_latent_heat


def implicit_general(obj):
Expand All @@ -15,9 +16,11 @@ def implicit_general(obj):
conductivity.

"""
n = obj.num_points

# initializes the matrixes for the equation systems
a = np.zeros((obj.num_points, obj.num_points))
b = np.zeros(obj.num_points)
a = np.zeros((n, n))
b = np.zeros(n)

# left boundary
a[0][0] = 1
Expand All @@ -27,15 +30,14 @@ def implicit_general(obj):
b[0] = obj.boundaries[0]

# right boundary
a[obj.num_points - 1][obj.num_points - 1] = 1
a[n - 1][n - 1] = 1
if obj.boundaries[1] == 0:
value = obj.temperature[obj.num_points - 2][0]
b[obj.num_points - 1] = value
b[n - 1] = obj.temperature[n - 2][0]
else:
b[obj.num_points - 1] = obj.boundaries[1]
b[n - 1] = obj.boundaries[1]

# creates the matrixes and solves the equation systems
for i in range(1, obj.num_points - 1):
for i in range(1, n - 1):
beta = obj.k[i] * obj.dt / \
(2 * obj.rho[i] * obj.Cp[i] * obj.dx * obj.dx)
sigma = obj.dt / (obj.rho[i] * obj.Cp[i])
Expand All @@ -52,38 +54,10 @@ def implicit_general(obj):
x = np.linalg.solve(a, b)

# latent heat
lheat = copy.copy(obj.lheat)
for i in range(1, obj.num_points - 1):
j = 0
for lh in obj.latent_heat[i]:
temper = obj.temperature[i][0]
if x[i] > lh[0] and temper <= lh[0] and lheat[i][j][1] != lh[1]:
en = obj.Cp[i] * obj.rho[i] * (x[i] - obj.temperature[i][0])
if en + lheat[i][j][1] >= lh[1]:
lheat[i][j][1] = lh[1]
energy_temp = lheat[i][j][1] + en - lh[1]
x[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
x[i] = obj.temperature[i][0]
if x[i] < lh[0] and temper >= lh[0] and lheat[i][j][1] != 0:
en = obj.Cp[i] * obj.rho[i] * (x[i] - obj.temperature[i][0])
if en + lheat[i][j][1] <= 0.:
lheat[i][j][1] = 0.
energy_temp = (en + lheat[i][j][1])
x[i] = obj.temperature[i][0] + \
energy_temp / (obj.Cp[i] * obj.rho[i])
else:
lheat[i][j][1] += en
x[i] = obj.temperature[i][0]
j += 1

y = copy.deepcopy(obj.temperature)

# updates the temperature list
for i in range(obj.num_points):
y[i][1] = x[i]
y[i][0] = x[i]
nx_list = x.tolist()
lheat = apply_latent_heat(nx_list, obj)

# pack into [current, next] pairs expected by the caller
y = [[nx_list[i], nx_list[i]] for i in range(n)]

return y, lheat
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