Chapter 5

FieldConvert is a utility embedded in Nektar++ with the primary aim of allowing the user to convert the Nektar++ output binary files (.chk and .fld) into formats which can be read by common visualisation and post-processing software, primarily Paraview/VisIt (in unstructured VTK .vtu format) or Tecplot/VisIt (in ASCII .dat or binary .plt formats). FieldConvert also allows the user to manipulate the Nektar++ output binary files by using some additional modules which can be called with the option -m which stands for module. Note that another flag, -r (which stand for range) allows the user to specify a sub-range of the domain on which the conversion or manipulation of the Nektar++ output binary files will be performed.

Almost all of the FieldConvert functionalities can be run in parallel if Nektar++ is compiled using MPI (see the installation documentation for additional info on how to implement Nektar++ using MPI). 1

 5.1 Basic usage
  5.1.1 Input formats
 5.2 Convert .fld / .chk files into Paraview, VisIt or Tecplot format
  5.2.1 Using the VTK library for output
 5.3 Convert field files between XML and HDF5 format
 5.4 Range option -r
 5.5 FieldConvert in NekPy
 5.6 FieldConvert modules -m
  5.6.1 Smooth the data: C0Projection module
  5.6.2 Calculate CFL number: CFL module
  5.6.3 Calculate Q-Criterion: QCriterion module
  5.6.4 Calculate λ2: L2Criterion module
  5.6.5 Add composite ID: addcompositeid module
  5.6.6 Add new field: fieldfromstring module
  5.6.7 Sum two .fld files: addFld module
  5.6.8 Combine two .fld files containing time averages: combineAvg module
  5.6.9 Concatenate two files: concatenate module
  5.6.10 Count the number of DOF: dof module
  5.6.11 Equi-spaced output of data: equispacedoutput module
  5.6.12 Extract a boundary region: extract module
  5.6.13 Calculate divergence: divergence module
  5.6.14 Compute the gradient of a field: gradient module
  5.6.15 Convert HalfMode expansion to SingleMode for further processing: halfmodetofourier module
  5.6.16 Extract a plane from 3DH1D expansion: homplane module
  5.6.17 Stretch a 3DH1D expansion: homstretch module
  5.6.18 Inner Product of a single or series of fields with respect to a single or series of fields: innerproduct module
  5.6.19 Interpolate one field to another: interpfield module
  5.6.20 Interpolate scattered point data to a field: interppointdatatofld module
  5.6.21 Interpolate a field to a series of points: interppoints module
  5.6.22 Interpolate a set of points to another: interpptstopts module
  5.6.23 Isocontour extraction: iscontour module
  5.6.24 Show high frequency energy of the Jacobian: jacobianenergy module
  5.6.25 Calculate mesh quality: qualitymetric module
  5.6.26 Evaluate the mean of variables on the domain: mean module
  5.6.27 Extract mean mode of 3DH1D expansion: meanmode module
  5.6.28 Project point data to a field: pointdatatofld module
  5.6.29 Print L2 and LInf norms: printfldnorms module
  5.6.30 Removes one or more fields from .fld files: removefield module
  5.6.31 Computes the scalar gradient: scalargrad module
  5.6.32 Scale a given .fld: scaleinputfld module
  5.6.33 Time-averaged shear stress metrics: shear module
  5.6.34 Stream function of a 2D incompressible flow: streamfunction module
  5.6.35 Boundary layer height calculation: surfdistance module
  5.6.36 Calculate vorticity: vorticity module
  5.6.37 Computing the wall shear stress: wss module
  5.6.38 Calculating the shape function Φ for an SPM case: phifile module
  5.6.39 Interpolate values for a point array: wallNormalData module
  5.6.40 Project velocity into body-fitted coordinate system: bodyFittedVelocity module
  5.6.41 Manipulating meshes with FieldConvert
 5.7 FieldConvert in parallel
 5.8 Processing large files in serial
  5.8.1 Using the part-only and part-only-overlapping options
  5.8.2 Using the nparts options
  5.8.3 Running in parallel with the nparts option