From d71faec93ec0a55c46810e0d178b2803ee89130c Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sat, 15 Jun 2019 20:45:27 +0200
Subject: Add support for generating a D3Q19 kernel

Note how this basically required no changes besides generalizing cell indexing
and adding the symbolic formulation of a D3Q19 BGK collision step.

Increasing the neighborhood communication from 9 to 19 cells leads to a
significant performance "regression": The 3D kernel yields ~ 360 MLUPS
compared to the 2D version's ~ 820 MLUPS.
---
 ldc_2d.py | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 ldc_2d.py

(limited to 'ldc_2d.py')

diff --git a/ldc_2d.py b/ldc_2d.py
new file mode 100644
index 0000000..0aa1e71
--- /dev/null
+++ b/ldc_2d.py
@@ -0,0 +1,79 @@
+import numpy
+import time
+
+import matplotlib
+import matplotlib.pyplot as plt
+matplotlib.use('AGG')
+
+from lbm import Lattice, Geometry
+
+import symbolic.D2Q9 as D2Q9
+
+def MLUPS(cells, steps, time):
+    return cells * steps / time * 1e-6
+
+def generate_moment_plots(lattice, moments):
+    for i, m in enumerate(moments):
+        print("Generating plot %d of %d." % (i+1, len(moments)))
+
+        velocity = numpy.ndarray(shape=tuple(reversed(lattice.geometry.inner_span())))
+        for x, y in lattice.geometry.inner_cells():
+            velocity[y-1,x-1] = numpy.sqrt(m[1,lattice.idx(x,y)]**2 + m[2,lattice.idx(x,y)]**2)
+
+        plt.figure(figsize=(10, 10))
+        plt.imshow(velocity, origin='lower', cmap=plt.get_cmap('seismic'))
+        plt.savefig("result/ldc_2d_%02d.png" % i, bbox_inches='tight', pad_inches=0)
+
+def cavity(geometry, x, y):
+    if x == 1 or y == 1 or x == geometry.size_x-2:
+        return 2
+    elif y == geometry.size_y-2:
+        return 3
+    else:
+        return 1
+
+boundary = """
+    if ( m == 2 ) {
+        u_0 = 0.0;
+        u_1 = 0.0;
+    }
+    if ( m == 3 ) {
+        u_0 = 0.1;
+        u_1 = 0.0;
+    }
+"""
+
+nUpdates = 100000
+nStat    = 5000
+
+moments = []
+
+print("Initializing simulation...\n")
+
+lattice = Lattice(
+    descriptor = D2Q9,
+    geometry   = Geometry(256, 256),
+
+    moments = D2Q9.moments(optimize = False),
+    collide = D2Q9.bgk(tau = 0.52),
+
+    boundary_src = boundary)
+
+lattice.setup_geometry(cavity)
+
+print("Starting simulation using %d cells...\n" % lattice.geometry.volume)
+
+lastStat = time.time()
+
+for i in range(1,nUpdates+1):
+    lattice.evolve()
+
+    if i % nStat == 0:
+        lattice.sync()
+        print("i = %4d; %3.0f MLUPS" % (i, MLUPS(lattice.geometry.volume, nStat, time.time() - lastStat)))
+        moments.append(lattice.get_moments())
+        lastStat = time.time()
+
+print("\nConcluded simulation.\n")
+
+generate_moment_plots(lattice, moments)
-- 
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