Align Paraview multiblock output filename with other volume output filenames. (#1930)

Author: danielmayer

SU2_CFD/src/output/COutput.cpp

@@ -557,9 +557,8 @@ void COutput::WriteToFile(CConfig *config, CGeometry *geometry, OUTPUT_TYPE form
 
         extension = CParaviewVTMFileWriter::fileExt;
 
-        /*--- The file name of the multiblock file is the case name (i.e. the config file name w/o ext.) ---*/
-
-        fileName = config->GetUnsteady_FileName(config->GetCaseName(), curTimeIter, "");
+        if (fileName.empty())
+          fileName = config->GetUnsteady_FileName(volumeFilename, curTimeIter, "");
 
         if (!config->GetWrt_Volume_Overwrite())
           filename_iter = config->GetFilename_Iter(fileName,curInnerIter, curOuterIter);