Salient features of USM3D (Legacy)
 Full NavierStokes: includes all cross terms
 Thermodynamic models
 perfect gas for AIR
 Parallel processing
 Parallel execution on multiple CPUs using decomposed zonal grid
 Message passing through MPI
 Time integrations
 Steady State (Implicit Point GaussSeidel & Explicit RungeKutta)
 2nd Order Time Stepping
 Newton time stepping
 Dual time stepping
 Upwind flux functions
 Roe’s Flux Difference Splitting (FDS)
 Van Leer’s Flux Vector Splitting (FVS)
 AUSM scheme
 HLLC scheme
 LDFSS Scheme
 MinMod and Superbee flux limiters and Eigenvalue limiter
 Turbulence Models
 SpalartAllmaras (SA) turbulence model
 SA with Detached Eddy Simulation (SADES)
 Menter ShearStress Transport (SST)
 kepsilon model

 Girimaji nonlinear shear stress
 Shi/Zu/Lumley nonlinear modelAlgebraic Reynolds Stress Model (ARSM)
 Transition tripping at prescribed locations
 Overset Chimera grids (static and dynamic)*
 integrated with DiRTlib by Dr. Ralph Noack, Univ. Alabama at Birmingham
 CDISC design within extracted subgrid zones
 Grid motion
 Solidbody or deforming grid motion
 Special sinusoidal oscillation
 Coupled with external motion controller
 6Degree of Freedom (6DOF) capability*
 Coupled with AEDC FDCADRE* and SixDOF controller by Dr. Greg Power, AEDC
 Trajectory integration
 Store/stage separation
 Boundary conditions
 Freestream inflow
 Symmetry
 Supersonic outflow
 Characteristic inflow/outflow
 Solid noslip wall
 Solid turbulent wall function
 Solid tangency wall
 Zonal boundary interface condition
 Doublefringe overlapping tetrahedral grids
 Periodic boundaries
 Trailingedge wake simulation
 Propulsion systems
 inlet with prescribed mass flow and swirl
 jet exhaust with swirl
 coupled jet exhaust with inlet
 Actuatordisc propellor model with radial load variation
 Portable (Linux clusters, SGI, HP, IBM, Mac)
 * Requires 3rd party software request
Convention used for coordinate system in USM3D
It is important to construct the computational grid in the correct coordinate system in order for alpha, beta, and the force & moments to be interpreted correctly.
The required coordinate system is:
 x – longitudinal body axis (positive in downstream direction)
 y – spanwise or lateral body axis (positive to pilot’s right if computing
lateral/directional coefficients on full configuration. Otherwise the ydirection is not important.)  z – vertical direction in body axis (positive upward)
Force & Moment sign conventions:
 Alpha (xz plane) – Positive nose up
 Beta (yz plane) – Positive for yaw to the left
 Pitching moment (xz plane) – Positive pitch up
 Rolling moment (yz plane) – Positive roll right
 Yawing moment (xy plane) – Positive yaw right
Nondimensionalization used in USM3D
The flow solver employs following scheme for the nondimensionalization of various parameters of interest.
Considering the convention used for the coordinate system in USM3D and the nondimensionalization scheme described above, the freestream and other relevant quantities assume the following nondimensional values/form.
where:
Sutherland’s law for the molecular viscosity mentioned above is given by: