The lower part of the figure depicts time-accurate calculations according to this method. First, the processor determines whether the time-accurate calculations have been completed. If not, the processor adjusts the physical time step or the maximum allowable value, CFLMAX, of the Courant- Friedrichs-Levy number. [The Courant-Friedrichs-Levy number (CFL) is the product of a time step and a speed characteristic of the flow.] Next, the processor generates a flowsolver input file using the adjusted physical time step or adjusted CFLMAX. If negative density or pressure is found in the output of the flow solver, then the physical time step or CFLMAX is further adjusted, a corresponding new flow-solver input file is generated, and the flow solver is run again. This subprocess is repeated, if necessary, until neither the pressure nor the density is negative. Next, the processor analyzes the force and moment histories and increments the run count. The processor then returns to the step in which it determines whether the timeaccurate or the steady-state calculations have been completed. If the time-accurate calculations are found to have been completed, or if the steady-state calculations have been completed with satisfactory results, then the processor writes the results into an output file.
This work was done by Roger Strawn of the U.S. Army and E. A. Mayda and C. P. van Dam of the University of California for Ames Research Center. For more information, down - load the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Information Sciences category. ARC-15649-1