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Commit 3b0f59f3 authored by Frederik Hennig's avatar Frederik Hennig Committed by Markus Holzer
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Fix: Broken He model population space forcing with zero-centered storage

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......@@ -91,7 +91,9 @@ import sympy as sp
from pystencils.sympyextensions import scalar_product
from lbmpy.maxwellian_equilibrium import get_equilibrium_values_of_maxwell_boltzmann_function
from lbmpy.maxwellian_equilibrium import (
discrete_maxwellian_equilibrium, get_equilibrium_values_of_maxwell_boltzmann_function
)
from lbmpy.moments import (
MOMENT_SYMBOLS, exponent_tuple_sort_key, exponents_to_polynomial_representations,
extract_monomials, moment_sort_key,
......@@ -304,14 +306,15 @@ class He(AbstractForceModel):
super(He, self).__init__(force)
def forcing_terms(self, lb_method):
rho = lb_method.zeroth_order_equilibrium_moment_symbol
u = sp.Matrix(lb_method.first_order_equilibrium_moment_symbols)
force = sp.Matrix(self.symbolic_force_vector)
cs_sq = sp.Rational(1, 3) # squared speed of sound
# eq. 6.31 in the LB book by Krüger et al. shows that the equilibrium terms are devided by rho.
# This is done here with subs({rho: 1}) to be consistent with compressible and incompressible force models
eq_terms = lb_method.get_equilibrium_terms().subs({rho: 1})
cqc = lb_method.conserved_quantity_computation
eq_terms = discrete_maxwellian_equilibrium(lb_method.stencil, rho=sp.Integer(1),
u=cqc.velocity_symbols, c_s_sq=sp.Rational(1, 3))
result = []
for direction, eq in zip(lb_method.stencil, eq_terms):
......
......@@ -43,8 +43,10 @@ def test_total_momentum(method_enum, zero_centered, force_model, omega):
collision_kernel = ps.create_kernel(collision, config=config).compile()
fluid_density = 1.1
def init():
dh.fill(ρ.name, 1)
dh.fill(ρ.name, fluid_density)
dh.fill(u.name, 0)
setter = macroscopic_values_setter(collision.method, velocity=(0,) * dh.dim,
......@@ -70,8 +72,13 @@ def test_total_momentum(method_enum, zero_centered, force_model, omega):
init()
time_loop(t)
dh.run_kernel(getter_kernel)
# Check that density did not change
assert_allclose(dh.gather_array(ρ.name), fluid_density)
# Check for correct velocity
total = np.sum(dh.gather_array(u.name), axis=(0, 1))
assert_allclose(total / np.prod(L) / F / t, 1)
assert_allclose(total / np.prod(L) / F * fluid_density / t, 1)
@pytest.mark.parametrize("force_model", force_models)
......
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