ZEUS Information

• ZEUS is an ZONA’s Euler Unsteady aerodynamic solver to provide aeroelastic solutions for complex configurations.
• It uses Cartesian grid and employs boundary layer coupling.
• Cell-centered finite volume method using Jameson’s artificial dissipation scheme.
• Dual-time stepping algorithm for unsteady solution.
• Automated mesh generation scheme that requires only the surface mesh for input.
• Overset grid capability for complex configuration.
• Included ZAERO 3D spline module and Nastran modal solution importer.
• Multi-grid acceleration for fast solution convergence.
• Generates either time-domain aeroelastic responses or frequency-domain generalized aerodynamic forces for flutter, LCO, and static/trim aeroelastic analysis.

• Because ZEUS solves the Euler’s equation with a small disturbance boundary condition, all required geometric information existing in ZAERO is sufficient for ZEUS input.
• ZEUS mesh is generated by an automated mesh generation scheme.
• Fuselage, wing, horizontal tail, vertical tail, launcher and pylons can be fitted into a single block of mesh.
• Tip missile with fins and under wing stores can be fitted into other blocks of mesh, respectively.
• Communication between blocks of mesh is accomplished through the overset grid scheme.
• Each block of mesh is automatically generated by a Y-Zone technique.
• 95% of the input for ZEUS is identical to that of ZAERO
  

All components within each block are projected on an X-Y plane. On this X-Y plane, all components are divided into several spanwise zones, called the Y-Zones. The Y-Zone technique can automatically generate the mesh by a line-tracing method that spans across all Y-Zones. An example of division of an aircraft model into spanwise zones is shown at right with descriptions of each zone listed below.

ZONE 1: Left launcher
ZONE 2: Outboard left wing
ZONE 3: Inboard left wing and outboard left horizontal tail
ZONE 4: Outboard left strake and inboard left horizontal tail
ZONE 5: Inboard left strake
ZONE 6: Fuselage
ZONE 7: Inboard right strake
ZONE 8: Outboard right strake and inboard right horizontal tail
ZONE 9: Inboard right wing and outboard right horizontal tail
ZONE 10: Outboard right wing
ZONE 11: Right launcher

• Because of the limitation of the ZEUS mesh, overset grid is necessary to model complex configurations such as aircraft with underwing stores.
• Store meshes are embodied in the aircraft mesh
• A “holecutting” scheme is developed to avoid the overset mesh from penetrating into the surface boundary of components (IBLANK array)
• A connectivity algorithm is derived to establish the communication between component meshes (interpolation among meshes in the overlapping region)
• During each time integration step, solution at each component mesh is first computed by running the ZEUS flow solver independently. Flow communication between meshes is obtained by interpolating flow solution in the overlapping region. Solution convergence within each time step is achieved by sub-iteration.

• ZAERO modal data importer is adopted for ZEUS to import the finite element model (FEM) grid point location, generalized mass, stiffness matrices, and mode shape from the structural modal solution output file (e.g. *.f06 of NASTRAN).
• Because ZAERO and ZEUS share the same surface mesh definitions, the ZAERO spline module can be directly adopted and integrated into ZEUS.
• Four spline methods are included: the thin plate spline (3D spline), the infinte plate spline (2D spline), the beam spline (1D spline), and the rigid body attachment (mode shape on aerodynamic mesh from a single FEM grid).