Note

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Export a field to VTKΒΆ

The objective here is to create a field and export it as a VTK file. A field is the agregation of a mesh \mathcal{M} of a domain \mathcal{D} \in \mathbb{R}^n and a sample of values in \mathbb{R}^d associated to each vertex of the mesh.

We note (\underline{t}_0, \dots, \underline{t}_{N-1}) the vertices of \mathcal{M} and (\underline{x}_0, \dots, \underline{x}_{N-1}) the associated values in \mathbb{R}^d.

A field is stored in the Field object that stores the mesh and the values at each vertex of the mesh. It can be built from a mesh and values or as a realization of a stochastic process.

import openturns as ot
import openturns.viewer as viewer
from matplotlib import pylab as plt

ot.Log.Show(ot.Log.NONE)

First, we define a regular 2-d mesh

discretization = [10, 5]
mesher = ot.IntervalMesher(discretization)
lowerBound = [0.0, 0.0]
upperBound = [2.0, 1.0]
interval = ot.Interval(lowerBound, upperBound)
mesh = mesher.build(interval)
graph = mesh.draw()
graph.setTitle("Regular 2-d mesh")
view = viewer.View(graph)
Regular 2-d mesh

We now create a field from a mesh and some values

values = ot.Normal([0.0] * 2, [1.0] * 2, ot.CorrelationMatrix(2)).getSample(
    len(mesh.getVertices())
)
for i in range(len(values)):
    x = values[i]
    values[i] = 0.05 * x / x.norm()
field = ot.Field(mesh, values)

We can export the field to a VTK files. It can be read later with an external program such as Paraview.

field.exportToVTKFile("field.vtk")

Display figures

plt.show()