56 lines
1.9 KiB
Python
56 lines
1.9 KiB
Python
"""
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End-to-end conservation tests: after a short run, total system mass
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and total system energy must be conserved to machine precision. These
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are the load-bearing tests for the "flux doubling" coupling mechanism.
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"""
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import numpy as np
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import pytest
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from tank_pipe.tank import Tank
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from tank_pipe.pipe import Pipe
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from tank_pipe.solver import run
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GAMMA = 1.4
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R_GAS = 287.0
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def _build_scenario():
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"""Default blowdown scenario at smaller scale — same physics, short run."""
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tank1 = Tank(V=5.0, P_init=10e6, T_init=300.0, gamma=GAMMA, R_gas=R_GAS)
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tank2 = Tank(V=10.0, P_init=101325.0, T_init=300.0, gamma=GAMMA, R_gas=R_GAS)
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pipe = Pipe(L=1.0, D=5e-3, N=20,
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P_init=101325.0, T_init=300.0, gamma=GAMMA, R_gas=R_GAS)
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return tank1, tank2, pipe
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def _total_mass(tank1, tank2, pipe):
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return tank1.mass + tank2.mass + float(np.sum(pipe.W[0, :] * pipe.area * pipe.dx))
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def _total_energy(tank1, tank2, pipe):
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return tank1.U + tank2.U + float(np.sum(pipe.W[2, :] * pipe.area * pipe.dx))
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def test_total_mass_conserved_over_short_run():
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tank1, tank2, pipe = _build_scenario()
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m_init = _total_mass(tank1, tank2, pipe)
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run(tank1, tank2, pipe, t_end=1e-3, cfl=0.5)
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m_final = _total_mass(tank1, tank2, pipe)
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rel_err = abs(m_final - m_init) / m_init
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assert rel_err < 1e-10, (
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f"Total mass not conserved: m_init={m_init:.6e}, "
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f"m_final={m_final:.6e}, rel_err={rel_err:.2e}"
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)
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def test_total_energy_conserved_over_short_run():
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tank1, tank2, pipe = _build_scenario()
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U_init = _total_energy(tank1, tank2, pipe)
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run(tank1, tank2, pipe, t_end=1e-3, cfl=0.5)
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U_final = _total_energy(tank1, tank2, pipe)
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rel_err = abs(U_final - U_init) / U_init
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assert rel_err < 1e-10, (
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f"Total energy not conserved: U_init={U_init:.6e}, "
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f"U_final={U_final:.6e}, rel_err={rel_err:.2e}"
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)
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