Files

• Input Data File (.dat)
• Grid File (.cgd)
• Flow File (.cfl)
• Global Newton File (.cfk)
• Boundary Data File (.tda)
• Time History File (.cth)
• List Output File (.lis)
• WIND Stop File (NDSTOP)
• Temperature and Transition Specification Files
• Chemistry Files (.chm)
• Reserved Files

A number of files are used by WIND in the course of a solution. The script file you run to submit WIND jobs will assign all the necessary files to their appropriate Fortran unit numbers, so you should not need to do any of that yourself. Each of the support files is described briefly below.

Input Data File (.dat)

The input data file is the primary control file for WIND and must be created for each case you want to run with the code. Input data and code options are entered through the use of descriptive keywords in this file. You should observe the following formatting rules in creating the input data file:

1. The first three lines of the file are reserved for geometry, flow condition, and arbitrary titles, respectively. Each of these titles may be up to 64 characters long. None of these first three lines may start with the (case-insensitive) word "Include".
   
   
2. Comment lines, beginning with a "/" character, may be placed anywhere in the file after the first three lines. Data file readability may be improved dramatically through the liberal use of comments - for example, separating logical sections of the data file: numerical algorithm, force integrations, test options, etc.
   
   
3. Block data, such as that specified in arbitrary inflow or chemistry cases, must be contiguous - only keywords corresponding to the block may reside between the beginning and ending block indicators (e.g., CHEMISTRY and ENDCHEMISTRY).
   
   
4. Keywords may be entered in upper or lower case.
   
   
5. Abbreviations for keywords may be used, as long as they are unique. If they are not, you may not get the results you expect. For example, it's not a good idea to use single-letter abbreviations for keywords.

The following is an example of a simple input data file:

   Geometric Title
   Flowfield Condition Title
   Optional Title
   Freestream static 0.9 14.7 530. 4. 0.
   Cycles 15
   Inviscid
   End

Grid File (.cgd)

The computational grid used by WIND for a particular case is stored in the grid file. In this file are stored the (x, y, z) coordinates of all computational grid points, zone coupling interpolation factors, and grid reference and scaling data.

This file was originally referred to as the common grid file, so named because the file was formatted according to Boeing's Common File Format (CFF). Starting with version 4.0 however, WIND also supports grid files in CGNS (CFD General Notation System) format. [Detailed information on the CGNS standard may be found at the CGNS web site .] Both common files and CGNS files are binary, and portable to virtually every hardware platform, except Cray, with no need for explicit data conversions.

Grid files for WIND may be created by several mesh-generation codes in either common file or CGNS format. If necessary, the cfcnvt utility may be used to convert a variety of other formats, including PLOT3D xyz format, to common file format.

Zone coupling, reference, and scaling data are added to common grid files using the GMAN program. Common grid files are also used in the CFPOST post-processing package. Neither GMAN nor CFPOST currently support CGNS files, however.

Keywords: CGNSBASE

Flow File (.cfl)

The flow file contains the computed flow field. For Navier-Stokes and Euler solutions, the file contains density, momentum, and energy data, and, for viscous solutions, turbulence data. The flow file also records the current solution cycle number to allow the file to be used for solution restarts.

Like the grid file, the flow file was originally referred to as the common flow file, but may now be written in either common file or CGNS format. Several graphical post-processing programs are able to read both common files and CGNS files.

The CFPOST post-processing package may be used with common flow files to produce other files for post-processing and/or to create flowfield plots directly. CFPOST does not currently support CGNS files, however.

Keywords: CGNSBASE

Global Newton File (.cfk)

The Global Newton file is a copy of the flow file used for Global Newton time marching. It holds the current sub-iteration of the time step. It is only created when Global Newton time marching is active, and is a scratch file. If the code aborts, the solution restarts from the conditions in the flow file, at the beginning of the time level, so the Global Newton file does not need to be saved.

Boundary Data File (.tda)

WIND's boundary data file is used during solution restarts, and results in smoother restarts, especially with higher-order boundary coupling. The file acts as a buffer for the transfer of zone coupling information and a holding bin for data needed throughout a WIND run but not stored in the grid or solution file.

Time History File (.cth)

The time history file is a common file which stores data resulting from the use of WIND's history tracking capability. The file contains a lookup table corresponding to the range of computational indices tracked during the run, time stamp data, and flowfield data for each time stamp. Upon completion of a time history run, the auxiliary program thplt may be used to view the contents of the time history file.

Keywords: HISTORY

List Output File (.lis)

The purpose of WIND's list output file is to echo the input from the input data file, track convergence and integration results, record CPU/job statistics, and log code error messages. The auxiliary program resplt may be used to extract convergence and integration data from the list output file and create a GENPLOT-style data file, which may be plotted with the plot command in the CFPOST post-processing package. For parallel-processing runs, this file also contains messages relating to the PVM system and to the allocation and operation of slave processors. Convergence data is written to this file for each of the equation sets solved during the run, including the Euler, Navier-Stokes, and non-algebraic turbulence model sets.

WIND Stop File (NDSTOP)

The stop file is used to stop WIND execution cleanly in the middle of a CFD solution. Although a solution may be stopped simply by killing the WIND process from the system queue, doing so will not ensure a clean update of all zonal flowfield data to the flowfield file. The stop file - named NDSTOP - provides a means to cleanly shut down a running solution, completing the current cycle or zone, performing zone coupling, updating the flowfield file, and removing all symbolic links to Fortran file unit numbers.

To stop the code, you must place one of two words in the stop file in the directory in which the WIND job is running. The word STOP in the stop file signals WIND to complete the current cycle (at the end of the last zone) and exit. In single-processing mode, you may also use the word STOPZONE in the stop file to stop WIND after completing the zone currently in memory. [In multi-processing mode, STOPZONE does the same thing as STOP.] You may then restart the code in your next run, starting at the next zone or back at zone one. Regardless of the existence of this file, WIND will stop if the requested number of cycles has been computed, or if your solution has converged.

During the clean-up procedure at the end of the job, the NDSTOP file is automatically removed.

Note that the directory in which the WIND job is running, where the NDSTOP file must be, is not necessarily the one you were in when the wind command was issued. If you don't use the -runinplace option to the wind script, the job will be run in a remote directory. The "root name" of the remote run directory may be specified using the -runroot option, or in response to a command line prompt. The default for the "root name" of the remote directory is /tmp. The full name of the remote directory will be rootname/userid/basename.scr, where rootname is the "root name" described above, userid is your userid, and basename is the base name of your .dat file.

On a Unix system, you might submit a simple "at" job for a later time as follows:

   at 0530 monday
   echo STOP > NDSTOP
   ^D

At 5:30 AM on the next Monday, the system would create the NDSTOP file with the word "STOP" in it. Note that this will not stop the run exactly at 5:30 AM; WIND must still complete the current cycle, which may take an hour or more for large cases.

Keywords: RESTART

Temperature and Transition Specification Files

WIND can read temperature and transition files, specifying the temperature or transition to turbulence on any boundary surface, that were created with the older tmptrn utility. This option is included for backward compatibility with WIND 2.0, and is only needed for an initial (i.e., non-restart) run. The wind script copies the files to the run directory, and WIND opens the files directly (unit 45) using the file names specified with the TTSPEC keyword. New applications should use the latest tmptrn utility to write the temperature/transition data into the flow (.cfl) file directly.

Keywords: TTSPEC

Chemistry Files (.chm)

The generalized chemistry files contain all the information WIND requires to compute a general chemistry mixture. A chemistry file has a header line, followed by three sections containing thermodynamic coefficients, finite rate coefficients, and transport properties.

Header

The header line must contain a single parameter, ispec, specifying the type of reaction rate and the format for the finite rate data. The format for the header line is:

   ispec     ISPEC

Thermodynamic Coefficients

This section of the chemistry data file contains the information necessary to compute the specific heat c_p for each species. The value of c_p is defined by a series of polynomials, each valid within a defined temperature range, of the form:

The format for this section is:

   THERMODYNAMIC COEFFICIENTS
   Title, line 1
   Title, line 2
   ns     NS
   Information defining species 1
   ...
   Information defining species ns

For each species, the information defining the species and for computing c_p, etc., is read as follows:

      read (26,100) name,ncurves,ds1,hm1,ds2,hm2,unk1,unk2,con,molwt
      do 10 ic = 1,ncurves
         read (26,110) t1,t2,(a(i,ic),i=1,5),shf(ic),F(ic)
   10 continue
  100 format (a8,7x,i5,4x,2(a2,f3.0),16x,f10.1,5x,f10.3)
  110 format (5e15.5)

Finite Rate Coefficients

This section of the file contains the reaction rate information. There are three possible formats for this section, depending on the value of ispec.

Format 1; ispec = 1, 4, 100-119.

This option may be used for any chemically reacting flow. Information is specified defining the forward reaction rate k_f and the equilibrium constant K. The rates themselves are computed using the equations

The various parameters and polynomial coefficients are read from the chemistry data file, in the following form:

   FINITE RATE COEFFICIENTS
   Title, line 1
   Title, line 2
   nreq ndeq     NREQ, NDEQ
   tfrmin        TFRMIN
   Information defining dissociation reaction 1
   ...
   Information defining dissociation reaction ndeq
   Information defining exchange reaction 1
   ...
   Information defining exchange reaction nreq - ndeq

For each reaction, the information defining the reaction and for computing the reaction rates is read as follows:

      read (26,100) r1,r2,p1,p2,S,D,(a(i),i=1,5),nthd
      do 10 i = 1,nthd
         read (26,120) spec,C
   10 continue
  100 format (4(a5,3x),2e12.4/5e12.4,i4)
  110 format (16x,a8,e12.4)

Format 2; ispec = 3, 130-139.

This option is similar to the previous one, except that the forward and backward reaction rates are computed separately, using the equations

The various parameters are read from the chemistry data file, in the following form:

   FINITE RATE COEFFICIENTS
   Title, line 1
   Title, line 2
   nreq ndeq     NREQ, NDEQ
   tfrmin        TFRMIN
   Information defining dissociation reaction 1
   ...
   Information defining dissociation reaction ndeq
   Information defining exchange reaction 1
   ...
   Information defining exchange reaction nreq - ndeq

For each reaction, the information defining the reaction and for computing the reaction rates is read as follows:

      read (26,100) r1,nr1,r2,nr2,p1,np1,p2,np2,Sf,Df,Cf
      read (26,110) Sb,Db,Cb
  100 format (4(a5,f3.1),3e12.4)
  110 format (32x,3e12.4)

Format 3; ispec = 120-129.

This option is only for global 1- or 2-reaction chemistry, and only for forward reactions. It is a quick method for simulating detonation problems, for example, in which reactions proceed only forward to completion. The forward reaction rates are computed using the equation

The various parameters and polynomial coefficients are read from the chemistry data file, in the following form:

   FINITE RATE COEFFICIENTS
   Title, line 1
   Title, line 2
   nreq ndeq     NREQ, NDEQ
   tfrmin        TFRMIN
   Information defining reaction 1
   ...
   Information defining reaction nreq

For each reaction, the information defining the reaction and for computing the reaction rates is read as follows:

      read (26,100) r1,nr1,r2,nr2,p1,np1,p2,np2,S,D,(a(i),i=1,5),nm
      read (26,110) Cb1,Cb2,C
  100 format (4(a5,f3.1),2e12.4/5e12.4,i4)
  110 format (2f8.3,8x,e12.4)

Transport Coefficients

This section of the chemistry data file contains the coefficients used to compute the laminar viscosity and thermal conductivity. The formulation is based on Wilke's law which uses Sutherland's law individually for each species. Thus for each species, there are equations of the form:

The various parameters and polynomial coefficients are read from the chemistry data file, in the following form:

   TRANSPORT COEFFICIENTS
   Title, line 1
   Title, line 2
   Information for species 1
   ...
   Information for species ns

For each species, the information is read as follows:

      read (26,100) name,ncurves,t1,t2,mu0,t0mu,smu
      read (26,110) k0,t0k,sk
      do 10 ic = 2,ncurves
         read (26,120) t1,t2,mu0,t0mu,smu
         read (26,110) k0,t0k,sk
   10 continue
  100 format (a8,2x,i5,2f10.3,1x,3e12.4)
  110 format (36x,3e12.4)
  120 format (15x,2f10.3,1x,3e12.4)

Reserved Files

Unit numbers 15, 21, and 55 are reserved for proprietary features, and should not be used by WIND developers.