GASP v4 Frequently Asked Questions

How do I convert Version 4.1 files to Version 4.2?

• Version 4.1 files can be converted to v4.2 using the utility gasp41to42. To use this utility, use the v4.1 input deck with the -i option. For example, if problem.inp is the name of the v4.1 input deck, then type:
  gasp41to42 -i problem.inp
  to convert.

How does the license manager work?

• AeroSoft uses the Elan license manager. Most licenses issued by AeroSoft are floating licenses. In other words, a single seat allows users to run on any platform, as long only one gasp flow solver executable per seat is executing at a single time. A single computer can act as the license server for many other computers. If the license server computer is on the same local subnet as the machine on which to run gasp, then no special set up or configuration is required. Once the license server is up and running, you can test the accessibility on other machines by running the command asi_elmusage (found in same directory as gasp). If the asi_elmusage command is unable to find a license server, you can force GASP to search a specific machine for a valid key by using the environment variable AEROSOFT_ELMHOST. (e.g. setenv AEROSOFT_ELMHOST @licenseserver.mycompany.com)

I installed the key and ran the license server, but the GASP v4 flow solver will not run?

• Check that the ELM license daemon is running (this is done on the machine that is running the license server).
• Run the command asi_elmusage to verify available keys (this should be done from the machine you are running GASP on).
• Send the message that you get from asi_elmusage and the message that GASP prints out to support@aerosft.com

What are the requirements to run GASP v4 in parallel across a network?

• AEROSOFT_HOME must be the same on all machines.
• The full path to problem must be the same.
• The user name must be the same on each machine within the network.
• The user must be able to do a remote shell login without prompting for a password.

How does post-processing work in Version 4?

• Post-processing is performed from within the GUI.
• A problem can be set up to post-process information during a run or at the end of a run.

What is the difference between export and domestic versions of GASP?

• Due to government control, AeroSoft is not allowed to make certain features of the GASP code available to customers outside the U.S. and to non U.S. citizens.
• The export GASP version (GASPex) does not contain: non-equilibrium vibrational energy modeling, prescribed or unprescribed moving body motion modeling, and COIL laser support.

Why does Version 4.0 require more memory than V3.2?

• V4.0 implements a fully implicit three-dimensional solution algorithm, which can require more memory than GASP V3.2 which only implements a plane implicit solver.
• You can reduce the required memory of V4.0 by partitioning zones and running explicit zonal and partition boundaries. Explicit boundary communication will trade reduced memory requirements for slower convergence behavior.

Why does Version 4.0 require more CPU time per iteration than V3.2 when both use the Jacobi algorithm?

• V4.0 now does implicit boundary conditions, which increases the size of the system (extra cells to solve). Speed difference is most pronounced when running 2-dimensional problems.
• The increase in CPU time should be balanced with better convergence rates due to the ability to run higher CFL numbers.

How do I know when a problem is converged?

• The residual is one measure of convergence, but do NOT rely on it solely.
• Version 4 allows the user to print out data on cycle increments. Use this feature to plot data that is relevant to the problem. For example, monitor skin friction values to ensure that the boundary layer is converged. For inviscid problems, monitor the pressure.

How do I run GASP v4 on an IBM SP3 machine using native MPI?

• poe -np # gasp --mpi -i problem.inp --block # -e AEROSOFT_HOME
• Some of the arguments are explained below:
  • -np # is the number of processors (as specified in input deck)
  • --block # is the run definition that you wish to run (0 = first run defn.)
  • -e is used to pass in the AEROSOFT_HOME directory

How do I run GASP v4 on an Alpha ES40 machine using native MPI?

• One command that we have found to work is: prun -p interactive -c4 gasp --mpi -i problem.inp --block # -e AEROSOFT_HOME
• Some of the arguments are explained below:
  • --block # is the run definition that you wish to run (0 = first run defn.)
  • -e is used to pass in the AEROSOFT_HOME directory

I'm running GASPv4 on an SGI (batch mode or interactive) and I get errors like ``[1] - 2558011 Stopped (SIGTTIN)''?

• add < /dev/null to the gasp argument line (.i.e. gasp -s -i problem.inp < dev/null)

AeroSoft, Inc. 2000 Kraft Drive, Suite 1400 Blacksburg, VA 24060 (540) 557-1900 Fax (540) 557-1919 Email questions@aerosoftinc.com