From OpenFOAMWiki

legacy VTK file format writer

Usage: foamToVTK [OPTIONS] options:

 -allPatches       combine all patches into a single file
 -ascii            write in ASCII format instead of binary
 -case <dir>       specify alternate case directory, default is the cwd
 -cellSet <name>   convert a mesh subset corresponding to the specified cellSet
 -constant         include the 'constant/' dir in the times list
 -excludePatches <wordReList>
                   a list of patches to exclude - eg '( inlet ".*Wall" )' 
 -faceSet <name>   restrict conversion to the specified faceSet
 -fields <wordList>
                   only convert the specified fields - eg '(p T U)'
 -latestTime       select the latest time
 -nearCellValue    use cell value on patches instead of patch value itself
 -noFaceZones      no faceZones
                   do not execute functionObjects
 -noInternal       do not generate file for mesh, only for patches
 -noLinks          don't link processor VTK files - parallel only
 -noPointValues    no pointFields
 -noZero           exclude the '0/' dir from the times list, has precedence
                   over the -zeroTime option
 -parallel         run in parallel
 -pointSet <name>  restrict conversion to the specified pointSet
 -poly             write polyhedral cells without tet/pyramid decomposition
 -region <name>    specify alternative mesh region
 -roots <(dir1 .. dirN)>
                   slave root directories for distributed running
 -surfaceFields    write surfaceScalarFields (e.g., phi)
 -time <ranges>    comma-separated time ranges - eg, ':10,20,40:70,1000:'
 -useTimeName      use the time name instead of the time index when naming the
 -srcDoc           display source code in browser
 -doc              display application documentation in browser
 -help             print the usage