def test_normal_shock_infinite_limit():
gamma = 1.4
ns = shocks.Shock(M_1=np.inf, gamma=gamma)
np.testing.assert_almost_equal(ns.M_2,
np.sqrt((gamma - 1) / 2 / gamma),
decimal=3)
np.testing.assert_almost_equal(ns.rho2_rho1, (gamma + 1) / (gamma - 1),
decimal=3)
def test_normal_shock_M_2():
"""Tests the computation of post-shock Mach number.
"""
M_1_list = [1.5, 1.8, 2.1, 3.0]
M_2_list = [0.7011, 0.6165, 0.5613, 0.4752]
ns_list = [shocks.Shock(M_1=M_1, gamma=1.4) for M_1 in M_1_list]
for i in range(len(ns_list)):
np.testing.assert_almost_equal(ns_list[i].M_2, M_2_list[i], decimal=4)
def test_oblique_shock_from_deflection_angle():
# Anderson, example 4.1
# Notice that only graphical accuracy is achieved in the original example
M_1 = 3.0
theta = np.radians(20.0)
os = shocks.Shock(M_1=M_1, theta=theta, weak=True)
np.testing.assert_almost_equal(os.M_1n, 1.839, decimal=2)
np.testing.assert_almost_equal(os.M_2n, 0.6078, decimal=2)
np.testing.assert_almost_equal(os.M_2, 1.988, decimal=1)
np.testing.assert_almost_equal(os.p2_p1, 3.783, decimal=1)
np.testing.assert_almost_equal(os.T2_T1, 1.562, decimal=2)
def test_normal_shock_ratios():
"""Tests normal shock ratios of thermodynamics properties.
"""
M_1_list = [1.5, 1.8, 2.1, 3.0]
p_ratio_list = [2.4583, 3.6133, 4.9783, 10.3333]
rho_ratio_list = [1.8621, 2.3592, 2.8119, 3.8571]
T_ratio_list = [1.3202, 1.5316, 1.7705, 2.6790]
ns_list = [shocks.Shock(M_1=M_1, gamma=1.4) for M_1 in M_1_list]
for i in range(len(ns_list)):
np.testing.assert_almost_equal(ns_list[i].p2_p1,
p_ratio_list[i],
decimal=4)
np.testing.assert_almost_equal(ns_list[i].rho2_rho1,
rho_ratio_list[i],
decimal=4)
np.testing.assert_almost_equal(ns_list[i].T2_T1,
T_ratio_list[i],
decimal=4)
def test_error_mach_angle():
with pytest.raises(ValueError):
shocks.Shock(M_1=5, beta=np.radians(10))
def test_error_max_deflection():
with pytest.raises(ValueError):
shocks.Shock(M_1=5, theta=np.radians(50))
def test_normal_shock_zero_deflection():
ns = shocks.Shock(M_1=2.0)
assert ns.theta == 0.0
def test_normal_shock_fails_subsonic_M_1():
with pytest.raises(ValueError):
shocks.Shock(M_1=0.8)
def test_normal_shock_default_specific_heat_ratio():
ns = shocks.Shock(M_1=2.0)
np.testing.assert_equal(ns.gamma, 7 / 5)
def test_normal_shock_constructor():
gamma = 1.4
M_1 = 2.0
shocks.Shock(M_1=M_1, gamma=gamma)
def test_parallel_shock_infinity_mach():
M_1 = np.inf
beta = 0.0
os = shocks.Shock(M_1=M_1, beta=beta)
assert os.M_1n == 0.0
assert np.isfinite(os.theta)