Fixed the order of steps in the periodic pipe test case

lbmpy_tests/advanced_streaming/test_periodic_pipe_with_force.py

@@ -107,7 +107,7 @@ class PeriodicPipeFlow:
 
         #   Periodicity
         self.periodicity_handler = PeriodicityHandling(
-            stencil, self.dh, self.pdfs.name,
+            self.stencil, self.dh, self.pdfs.name,
             streaming_pattern=self.streaming_pattern, zeroth_timestep=self.zeroth_timestep)
 
         #   Boundary Handling
@@ -129,14 +129,13 @@ class PeriodicPipeFlow:
         self.dh.run_kernel(self.init_kernel)
 
     def step(self):
-        # Boundaries
-        self.bh(between_timesteps=self.between_timesteps[self.t_modulus])
-
+        #   Order matters! First communicate, then boundaries, otherwise
+        #   periodicity handling overwrites reflected populations
         # Periodicty
         self.periodicity_handler(self.timesteps[self.t_modulus])
 
-        # Macroscopic Values
-        self.dh.run_kernel(self.getter_kernels[self.t_modulus])
+        # Boundaries
+        self.bh(between_timesteps=self.between_timesteps[self.t_modulus])
 
         # Here, the next time step begins
         self.t_modulus = (self.t_modulus + 1) % len(self.timesteps)
@@ -148,6 +147,9 @@ class PeriodicPipeFlow:
         if not self.inplace:
             self.dh.swap(self.pdfs.name, self.pdfs_tmp.name)
 
+        # Macroscopic Values
+        self.dh.run_kernel(self.getter_kernels[self.t_modulus])
+
     def run(self, iterations):
         for _ in range(iterations):
             self.step()
@@ -181,5 +183,6 @@ def test_periodic_pipe(stencil, streaming_pattern):
             prev_pattern = key[1]
             assert_allclose(
                 u, prev_u,
+                rtol=1, atol=1e-16,
                 err_msg=f'Velocity field for {streaming_pattern} differed from {prev_pattern}!')
     all_results[(stencil, streaming_pattern)] = u