Providing Quality CFD
Software and Solutions

GASP: Features


Basic Features

  • Solves steady and unsteady 3-D, Reynolds-Averaged, Navier-Stokes Equations (RANS) and subsets:
    -- Thin-layer Navier-Stokes (TLNS)
    -- Parabolized Navier-Stokes (PNS)
    -- Euler equations
    -- Incompressible Navier-Stokes
  • Solves steady and unsteady 3-D heat equation including conjugate heat transfer
  • Solves for stress and displacements due to thermal or applied loads.

Physical Modeling - Fluxes

  • Roe, Modified-Roe, Van Leer, HLLE+ and AUSM+ flux splittings
  • Yee low dissipation flux scheme
  • Preconditioned-Roe (extends flows to low Mach numbers)
  • Preconditioned Weiss-Smith flux scheme
  • Artificial compressibility flux option for incompressible, perfect gas flows
  • Higher order MUSCL reconstruction
  • True high-order ENO reconstruction

Physical Modeling - Thermodynamics

  • Equilibrium and non-equilibrium (U.S. only) thermodynamics models
  • NASA GRC extended curve fit option
  • Extended transport properties for air to 30,000 K

Physical Modeling - Chemistry Models

  • Species and Reaction databases for thermochemical properties
  • Stand alone database manager (GUI based)
  • Extended rate equation curve fits
  • Complete reaction sets for existing chemistry models
  • Park's two-temperature kinetic model for ionizing air

Physical Modeling - Two Phase Flow

  • Lagrangian formulation for particle tracking
  • Support for solid and liquid particles
  • Evaporation models
  • Compatible with steady and time dependent simulations
  • Wall rebound models
  • Drag models

Physical Modeling - Turbulence Models

  • Baldwin-Lomax algebraic model in any two logical directions (structured grids only)
  • Spalart Allmaras one-equation model
  • K-epsilon (High Reynolds Number, Chien and Lam Bremhorst)
  • Wilcox K-omega (1988, 1998, and 2006 versions) with compressibility correction.
  • K-length (Smith and Goldberg)
  • Mentor's SST model for K-omega
  • Reynolds Stress Model (Wilcox Stress-Omega)
  • Detached Eddy Simulation (DES) based on Spalart Allmaras model and SST models
  • Large Eddy Simulation (LES) hybrid model based on the work by Gieseking et. al.
  • Supports user-input intermittency values for transition modeling

Physical Modeling - Solid Thermodynamics

  • Material database with properties
  • Variable temperature properties supported
  • Solids with different materials supported

Physical Modeling - Mechanical Stress

  • Solves for material displacements due to external forces or thermal stress


  • Support for PLOT3D, TECPLOT, Ensight and Fieldview
  • Simplified user interface for computing integrated quantities (e.g., lift and drag)
  • Support for blanking within PLOT3D type output
  • English, SI, and user defined unit systems
  • Automatic execution of post-processing at end of CFD run
  • Access to all time levels stored in the solution files
  • User defined output variables



  • Multi-block structured/unstructured grid topology
  • Unstructured mesh support for tetrahdra, hexahedra, prisms, and pyramids
  • Chimera/Overset grids (structured grids only)
    -- Built-in hole-cutting and stencil selection
    -- Robust treatment of orphans
    -- Surface projection for overlapping grids
    -- Dual fringe point interpolation for increased spatial accuracy
    -- 3-D visualization and statistics for holes, interpolation cells, and orphans
  • Point-to-point and non-matching zonal boundary interpolation
    -- Automated point-to-point zonal boundary detection
  • Automated mesh sequencing

Temporal Accuracy

  • Steady state option
  • 1st, 2nd, and 3rd order time accurate option
  • Implicit Dual-time-stepping and Newton sub-iterations
  • Explicit Runge-Kutta option for time accurate flows
  • Solution file can save separate solutions incrementally in time
  • Time-dependent freestream conditions applied to any boundary condition

Motion Modeling (U.S. Only)

  • Kinematics models:
    -- 6 DOF models (multiple bodies with separate weights, c.g.'s and moments of intertia)
    -- Constrained motion database
  • Chimera calculations automated between time steps

Time Integration

  • Integration with Portable Extensible Toolkit for Scientific Computation (PETSc) library
  • Full Implicit 3-D solvers (Symmetric Point Gauss Seidel, Point Jacobi, and GMRES)
  • Implicit coupling across point to point zonal boundaries
  • Implicit boundary conditions
  • Uncoupling of systems including turbulence and chemistry for improved computational efficiency
  • Operator splitting for chemical source terms (using DVODE)
  • Euler Explicit Solver

Parallel Computing

  • Distributed memory model using MPI
  • Support for most parallel computers, including clusters
  • Integrated domain decomposition is transparent to the user
  • Support for full implicit time integration in parallel
  • Parallel hole cutting and Chimera stencil searches
  • Support for semi-automated load balancing
  • Different domain decomposition on different grid sequences

Graphical User Interfaces

  • All GUI interfaces integrated into single application (both pre- and post-processing in a single application)
  • Complete integration with the 3-D viewing window
  • Most features accessible from a single window
    -- Extensive use of "tab sheets" and tables for organization and layout
  • Graphics states saved in problem file


  • Binary files for both solution and grid are platform independent
  • Solution and grid are in separate files (including those for saved time steps)
  • Support for user-specified unit systems

Solution Visualization

  • Leverages VTK open source library
  • Support for most visualization primitives
    -- Line or flooded contours, isosurfaces, velocity vectors streamlines using tubes, ribbons, and bubbles, cutting planes
  • Line plotting from within the GUI
  • Creation of movies and snapshots from GUI