Add jet, surface and fixed-patch tests and runnable examples

tests/unit/test_initializers.py

@@ -0,0 +1,68 @@
+"""Initializer invariants on a host field; no CUDA context is required."""
+from types import SimpleNamespace
+
+import numpy as np
+import pytest
+from scipy.special import expi
+
+from CelerisLab.lbm.descriptors import D2Q9_EX, D2Q9_EY
+from CelerisLab.lbm.equilibrium import compute_feq_d2q9
+from CelerisLab.lbm.initializers import _oseen_vortex, add_vortex
+
+
+class HostField:
+    def __init__(self):
+        self.nx = self.ny = 7
+        self.nq = 9
+        self.cfg = SimpleNamespace(is_d2q9=True, viscosity=.02,
+                                   streaming="double_buffer")
+        self.ddf = np.repeat(compute_feq_d2q9(1.2, .04, .01)[:, None],
+                             49, axis=1).ravel()
+
+    def download_ddf(self):
+        pass
+
+    def upload_ddf(self):
+        pass
+
+    def _read_lattice_vectors(self):
+        return np.asarray(D2Q9_EX), np.asarray(D2Q9_EY)
+
+
+@pytest.mark.parametrize("kind", ["lamb", "oseen", "taylor"])
+def test_zero_strength_preserves_moving_nonunit_density_equilibrium(kind):
+    field = HostField()
+    before = field.ddf.copy()
+    add_vortex(field, (3, 3), 2., 0., kind)
+    np.testing.assert_allclose(field.ddf, before, rtol=2e-6, atol=2e-8)
+
+
+def test_oseen_center_limit_and_original_model_away_from_center():
+    radius, strength = 2., .02
+    r = np.array([0., 1e-10, 1e-5, .2, 1., 10.])
+    with np.errstate(all="raise"):
+        u, v, p = _oseen_vortex(r, np.zeros_like(r), radius, strength)
+    assert np.all(np.isfinite(p))
+    assert u[0] == v[0] == 0
+    np.testing.assert_allclose(p[:2], -4*radius**2*strength**2*np.log(2),
+                               rtol=1e-12)
+    z = 4*r[3:]**2/radius**2
+    kappa = 2*np.pi*radius**2*strength
+    original = -kappa**2/(8*np.pi**2*r[3:]**2) * (
+        -2*z*(expi(-z)-expi(-2*z)) + (1-np.exp(-z))**2)
+    np.testing.assert_allclose(p[3:], original, rtol=2e-13)
+
+
+def test_oseen_grid_center_stays_finite():
+    field = HostField()
+    add_vortex(field, (3, 3), 2., .02, "oseen")
+    assert np.isfinite(field.ddf).all()
+
+
+def test_esopull_is_rejected_before_editing_raw_storage():
+    field = HostField()
+    field.cfg.streaming = "esopull"
+    before = field.ddf.copy()
+    with pytest.raises(NotImplementedError, match="time/parity"):
+        add_vortex(field, (3, 3), 2., .02)
+    np.testing.assert_array_equal(field.ddf, before)