OVERFLOW-D
Milestones
1QFY97
- Release SEQUENTIAL version for ALPHA testing - (released 11/96)
4QFY97 - Release SCALABLE version for ALPHA testing - (released 10/97)
4QFY98 - Release major ALPHA update of SCALABLE code - (released 9/98)
3QFY99 - Release SCALABLE version for BETA testing - (released 6/99)
3QFY00 - Final Release of SCALABLE OVERFLOW-D
Status of OVERFLOW-D
OVERFLOW-D is a general purpose
Navier-Stokes solver for problems that may involve relative motion between configuration
components. The code uses overset structured grids to accommodate arbitrarily
complex geometries while, on a component-wise basis, retain the computational advantages
inherent to structured data. OVERFLOW-D has recently been released for BETA-testing
and comes with complete documentation, a set of examples, and an easy-to-use overset grid
generation package called OVERGRID.
OVERFLOW-D is based on the well known NASA OVERFLOW code, but has
been significantly enhanced to accommodate moving body applications, facilitate accuracy
control via solution adaption, and run efficiently on scalable computers. Makefiles
to compile the software on IBM-SP, Origin 2000, Sun 10000, and Cray T3E platforms are
provided with the code. OVERFLOW-D uses MPI to enable inter-processor communication.
OVERFLOW-D employs a powerful discretization paradigm that partitions
the problem domain into near-body and off-body regions. The near-body region
includes the surface geometry of all configuration parts being considered and the volume
of space that extends a short distance above the respective surfaces. The near-body
portion of the domain is discretized in a classical "Chimera'' fashion.
Near-body grids are generated in a pre-process using standard grid generation packages
(OVERGRID is especially well suited to this task).
The off-body portion of the domain encompasses the near-body domain and
extends to the far-field boundaries of the problem. OVERFLOW-D automatically
discretizes the off-body domain with uniform Cartesian grid components (structured) of
varying levels of resolution capacity. By default, off-body resolution capacity is
set based on proximity to near-body components. Users can run simulations on the
near-body and default off-body grid systems, or can enable solution adaption. With
adaption enabled, OVERFLOW-D allocates off-body grid resolution based on proximity to
near-body components and results of estimates of solution error. Of course, error
estimation is carried out automatically by OVERFLOW-D. In all cases, OVERFLOW-D
organizes grid components into groups of equal size. Then, on parallel computers,
groups are assigned to processors. Scalability is realized in a group-wise fashion.
OVERFLOW-D can be used to simulate moving body applications that
involve arbitrary rigid-body motion, prescribed motion, or maneuvers. OVERFLOW-D has
a general 6-degrees-of-freedom model (6-DOF) that allows body motion to respond to
aerodynamic loads as well as applied forces and moments associated with separation
mechanisms. All OVERFLOW-D functionality is tightly coupled, including 6-DOF, domain
connectivity, solution adaption, etc., in order to maximize computational efficiency for
such applications.
OVERFLOW-D has been tested on a range of applications that have
practical importance, several of which are described in AIAA
Paper 99-3302-CP (see proceedings of the 14th AIAA CFD Conference, pp. 469-483).
Details about the overset grid generation package that comes with OVERFLOW-D (viz., OVERGRID).
Algorithm
basics of OVERFLOW-D
EXAMPLES of OVERFLOW-D Simulation Capability
NASA Ames Research Center, Moffett Field CA 94035-1000, (650) 604-5000
Privacy Statement
URL: http://rotorcraft.arc.nasa.gov/
This Website Maintained By: Randall L. Peterson.
Responsible NASA Official: Dr. William Warmbrodt (Chief)
Ames Research Center Homepage
NASA Homepage
