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Overview of USM3D-ME

Salient features of USM3D-ME

  • Full Navier-Stokes: 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 Gauss-Seidel & Explicit Runge-Kutta)
    • 2nd Order Time Stepping
  • Upwind flux functions
    • Roe’s Flux Difference Splitting (FDS)
    • Van Leer’s Flux Vector Splitting (FVS)
    • HLLE scheme
    • HLLC scheme
  • Flux Limiters
    • Barth Jesperson
    • Van Leer
    • Van Albada
    • Venkat
    • Minmod
  • Turbulence Models
    • Spalart-Allmaras (SA) turbulence model
      • Standard SA model
      • SA model with negative provisions (SA-neg)
      • Rotation correction
      • Quadratic Constitutive Relation (QCR-2000) for calculating Reynolds stresses
    • Transition tripping at prescribed locations
  • Boundary conditions
    • Freestream inflow
    • Symmetry
    • Supersonic outflow
    • Characteristic inflow/outflow
    • Solid no-slip wall
    • Solid turbulent wall function
    • Solid tangency wall
    • Trailing-edge wake simulation
    • Propulsion systems
      • coupled jet exhaust with inlet
      • source-term based propeller model
  • Portable (Linux clusters, SGI, HP, IBM, Mac)

    • Convention used for coordinate system in USM3D-ME

    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:Top and side view computational grid in the correct coordinate system showing coordinates for alpha, beta, and the force & moments

    • 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 y-direction is not important.)
    • z – vertical direction in body axis (positive upward)

    Force & Moment sign conventions:

    • Alpha (x-z plane) – Positive nose up
    • Beta (y-z plane) – Positive for yaw to the left
    • Pitching moment (x-z plane) – Positive pitch up
    • Rolling moment (y-z plane) – Positive roll right
    • Yawing moment (x-y plane) – Positive yaw right

    Nondimensionalization used in USM3D-ME

    The flow solver employs following scheme for the nondimensionalization of various parameters of interest.

    Considering the convention used for the coordinate system in USM3D-ME 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: