tional fluid dynamics code to a number of scal- 

 able parallel computers, the scientists simulated 

 applications involving moderately complex 

 geometries. For example, a simple powered lift 

 vehicle that includes a wing and two lifting jet- 

 son is shown on the previous page. Navier 

 Stokes computations were performed to simulate 

 flow past a delta wing with thrust reverser jets in 

 a ground effect environment (takeoff and land- 

 ing). These preliminary simulations will provide 

 insight into the computational interaction of 

 thrust elements, and upwash and reingestion of 

 hot air and gases, leading to significant improve- 

 ments in aerodynamic performance. 



Improved design processes for advanced aircraft 

 and spacecraft through the use of advanced com- 

 putational fluid dynamics and structural analyses 

 is also the subject of research by scientists at 

 Langley Research Center. Scientists are focus- 

 ing on the design and modeling of a High Speed 

 Civil Transport (HSCT). One of the greatest 

 challenges in modeling the fluid dynamics of 

 these vehicles is developing mathematical equa- 

 tions that accurately simulate turbulent airflow. 

 Turbulent flow simulations currently used lose 

 accuracy at high speeds. Development of an 

 optimal airframe design for a HSCT involves 

 thousands of design iterations, each requiring a 



Airspeed contours around a three-dimensional aircraft traveling at Mach 0. 77 are revealed by using an 

 advanced simulation method (lower figure). Blue areas represent slower moving air. yellow and red the 

 fastest moving air Flow calculations for this complex geometry were based on the unstructured mesh 

 shown in the upper figure. 



127 



