calculate superficial velocity

bird/postprocess/find_sup_velocity.py

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+"""
+extract data, using Paraview-python modules, to numpy arrays
+
+This script is for probing the superificial velocity of the gas (air)
+
+""" 
+
+# Jonathan Stickel, Hariswaran Sitaraman; 2016
+
+
+import numpy as np
+from paraview import simple as pv
+import vtk.numpy_interface.dataset_adapter as dsa 
+import os
+from sys import argv
+
+#holdup=float(argv[1])
+holdup=0.0
+# reset stuff
+
+# clear "sources" 
+for f in pv.GetSources().values():
+    pv.Delete(f)
+
+ofreader = pv.OpenFOAMReader(FileName = '.') # just need to provide folder
+ofreader.CaseType = 'Reconstructed Case'
+t = np.array(ofreader.TimestepValues)
+N = t.size
+print(t)
+# set time to something other than zero to avoid errors about unset fields
+pv.UpdatePipeline(time = t[-1])
+
+# if needed, evaluate the point locations used in the simulation
+ofvtkdata = pv.servermanager.Fetch(ofreader)
+ofdata = dsa.WrapDataObject( ofvtkdata)
+ofpts = np.array(ofdata.Points.Arrays[0])
+ptsmin = ofpts.min(axis=0) # minimum values of the three axes
+ptsmax = ofpts.max(axis=0) # maximum values of the three axes
+print(ptsmin)
+print(ptsmax)
+
+# threshold filter to get only the "aerated liquid"; specify cell data or point
+# data in first element of Scalars by CELLS or POINTS
+liquidthreshold = pv.Threshold(Input=ofreader, Scalars=['CELLS', 'alpha.gas'],\
+                               #ThresholdRange=[0., 0.6])
+                               LowerThreshold=0,UpperThreshold=0.6,ThresholdMethod='Between')
+
+ofvtkdata = pv.servermanager.Fetch(liquidthreshold)
+ofdata = dsa.WrapDataObject( ofvtkdata)
+ofpts = np.array(ofdata.Points.Arrays[0])
+ptsmin_lt = ofpts.min(axis=0) # minimum values of the three axes
+ptsmax_lt = ofpts.max(axis=0) # maximum values of the three axes
+print(ptsmin_lt)
+print(ptsmax_lt)
+
+calc1  = pv.Calculator(Input=ofreader, AttributeType='Cell Data',\
+                         ResultArrayName='vflowrate',\
+                         Function='"alpha.gas"*"U.gas_Y"')
+
+# create a new 'Slice'
+#yslice = 0.95*ptsmax[1] # near, but not exactly, at the top
+yslice = 0.5*(ptsmax_lt[1]+holdup*ptsmax_lt[1])
+print("slice at %g" % yslice)
+slice1 = pv.Slice(Input=calc1)
+slice1.SliceType.Origin = [0.0, yslice, 0.0]
+slice1.SliceType.Normal = [0.0, 1.0, 0.0]
+
+# integrate all variables
+int1 = pv.IntegrateVariables(Input=slice1)
+
+# get volume-averaged values (in the liquid) as a function of time
+# for subsampling the data to reduce post-processing time:
+interval = 1 # how often to grab the data; '1' means every timepoint
+idx = range(0,N,interval)
+tint = t[idx]
+nint = tint.size
+sl1_vfrate = np.zeros(nint)
+area = np.zeros(nint)
+p = np.zeros(nint)
+
+# values
+for i in range(0,nint):
+    pv.UpdatePipeline(time=tint[i], proxy=int1)
+    idat1 = dsa.WrapDataObject( pv.servermanager.Fetch(int1) )
+    sl1_vfrate[i]  = idat1.CellData['vflowrate'].item()
+    area[i] = idat1.CellData['Area'].item()
+    p[i] = idat1.CellData['p'].item()
+    print("processing time = %g" % tint[i],sl1_vfrate[i]/area[i],p[i]/area[i])
+
+# take average
+vs = sl1_vfrate / area
+p = p / area # pressure in the slice
+
+outfile=open("superfvel.dat","w")
+
+print("average superficial velocity towards later half of time:%e"%(np.mean(vs[int(nint/2):nint])))
+
+for i in range(nint):
+	outfile.write("%e\t%e\n"%(tint[i],vs[i]))
+
+outfile.close()
+
+#plt.plot(tint, vs)
+#plt.show()
+