Tdyn reference manual


Executing Tdyn Solver

Tdyn solver can be comfortably started through PREPOST Calculate menu. Once the analysed problem is defined (i.e. the geometry is created) the boundary conditions assigned, and the mesh is generated, the Start button in the Calculate menu (or the Calculate icon) can be pressed (as shown in Figure 5).

When the Start  button is pressed, the system writes the input file for the calculation module (the "calculation file") called ProblemName.flavia into the ProblemName.gid directory, and then the tdyn?d.bat file from the Tdyn problemtype directory is executed, with the following arguments:

Argument 1: Problem name

Argument 2: Problem directory

Argument 3: Problemtype directory

From within the tdyn?d.bat batch file, the program executable tdyn?d.exe is called, with the name of the input file given as an argument.

Now tdyn?d.exe is started and creates a number of output files:

File name

Description

 

ProblemName.flavia.res

Results file

ProblemName.flavia.war

"Output View" file

ProblemName.flavia.for

Forces file

ProblemName.flavia.rst

Restart file

ProblemName.flavia.tim

Time table

ProblemName.flavia.sat

Sink & Trim data

ProblemName.flavia.ram.res

Forces results for structural analysis using Ram-Series

ProblemName.flavia.ram.msh

Mesh for structural analysis using Ram-Series

ProblemName.flavia.err

Error message (file created only if Tdyn exits with an error)

 

Remarks:

a)      ProblemName.flavia.war
While tdyn?d.exe is running, information about the process convergence and advancement can be displayed by selecting the respective process in the Calculate window and pressing Output view (or using the corresponding icon). The information displayed is contained in the ProblemName.flavia.war file, which is updated at every time-step.

b)      ProblemName.flavia.res
When pressing Postprocess in Custom GiD, this file is loaded, and the results it contains can be visualized in the post-processing module.

Also note that each calculation will delete a previous results file that might exist in this directory, unless it has been renamed before the new calculation process has been started.

c)      ProblemName.flavia.rst
The restart file contains the velocities, pressures, and other relevant data of the last time-step that has been written into the restart file. If Tdyn is started with the option Restart: On (that have to be set in the PROBLEM window) the file ProblemName.flavia.rst is read and the calculation will be restarted using the last time-step data as initial condition.

This file is updated each time-step that the results are written into the results file (ProblemName.flavia.res). Thus even a process that has not yet terminated can be killed and restarted with the option Restart: On, without having to recalculate all the time steps from the beginning. By killing the process, only the time steps from the last step that has been written into the results file onwards will be "lost" and will have to be recalculated in case of a restart.

Note that the restart file will be written in any case - even in the case that a calculation is started with the Restart: Off option.

Also note that each time the restart file is updated, as well as with each new calculation, a restart file that might already exist in the problem directory will be deleted unless it has previously been renamed.

d)      ProblemName.flavia.for
The forces file contains the forces and moments that act on the surfaces with Fluid Body properties. Forces are often used to evaluate the convergence of a simulation. The file can be opened from within Custom GiD postprocess, using the menu option View_Results >Forces_Graphs or in a spreadsheet program (like MS Excel) or another plotting utility (like Gnuplot). The first few time steps should be excluded from the graph, because the forces can oscillate at very high values due to the start up process, which can change the order of magnitude of the graph scales. Last results written in this file and some general information can be seen from within Custom GiD postprocess, using the menu option View_Results >Forces_On_Bodies.

 

e)      ProblemName.flavia.tim
The timetable file contains a report of the execution time used by different parts of the problem. The file can be opened from within Custom GiD post-process, using the menu option View_Results >Time_Table. This file is only available after the succesful calculation of a problem.