add example

Author: CyrilleBonamy

doc/conf.py

@@ -65,6 +65,7 @@
 ]
 
 sphinx_gallery_conf = {
+    'filename_pattern': '/',
     # path to your examples scripts
     'examples_dirs': '../examples',
     # path where to save gallery generated examples

examples/calc_0_avgfield.py

@@ -0,0 +1,39 @@
+"""
+Postprocessing example : Spatial average
+========================================
+
+This example doesn't do much, it reads and makes a spatial average of OpenFoam
+fields
+"""
+
+###############################################################################
+# First read the fields
+# ---------------------
+#
+# .. note:: It just reads a scalar and vector field and store it in variables
+#
+# import readfield function from fluidfoam package
+from fluidfoam import readfield, getVolumes
+
+sol = '../output_samples/bin/'
+timename = '0'
+
+alpha = readfield(sol, timename, 'alpha')
+U = readfield(sol, timename, 'U')
+
+###############################################################################
+# Now read the dV from the mesh
+# -----------------------------
+#
+centr,dV = getVolumes(sol)
+
+###############################################################################
+# Finally calculate the average of the fields
+# -------------------------------------------
+#
+import numpy as np
+avgfield = np.sum(alpha*dV)/np.sum(dV)
+avgU = np.sum(U*dV, axis=1)/np.sum(dV)
+
+print("Mean value of the alpha field = ", avgfield)
+print("Mean value of the velocity vectorfield = ", avgU)