Accession Number : ADA311353

Title :   Free-Stream Turbulence Effects on Stagnation Point Turbulence and Heat Transfer.

Descriptive Note : Final technical rept. 1 Mar 91-29 Feb 96,

Corporate Author : STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Lele, Sanjiva K. ; Bae, Sungwon

PDF Url : ADA311353

Report Date : 30 MAY 1996

Pagination or Media Count : 38

Abstract : Stagnation point flow and heat transfer under free-stream turbulence was studied. A new code and an optimized scheme were developed for this study. The optimized scheme was found to significantly save the computational cost. In addition, methods for prescribing realistic inflow turbulence were developed. Simulations with organized inflow disturbances were conducted to study the effect of spanwise length scale and intensity on the enhancement of wall heat transfer and skin friction. Three regimes were identified depending on the spanwise length scale, 'damping', 'attached amplifying', and 'detached amplifying' regimes. In the attached amplifying regime the enhancement of skin friction and heat transfer increases with the intensity of the inflow disturbance, but saturates for larger spanwise length scales. In all cases studied the heat transfer enhancement was 4-5 times larger than the skin friction enhancement. Finally, direct numerical simulations (DNS) of stagnation point flow with moderate grid resolution were conducted to study turbulence statistics. Mean profiles of u velocity and temperature were compared with laminar profiles, and the statistics of turbulence kinetic energy were obtained. The simulations have not completed yet, and preliminary results are included in this report.

Descriptors :   *HEAT TRANSFER, *TURBULENCE, MATHEMATICAL MODELS, ALGORITHMS, COMPUTERIZED SIMULATION, OPTIMIZATION, DAMPING, TURBULENT FLOW, VORTICES, COMPUTATIONAL FLUID DYNAMICS, FLOW FIELDS, TEMPERATURE GRADIENTS, KINETIC ENERGY, HYDRODYNAMIC CODES, MACH NUMBER, FREE STREAM, LAMINAR FLOW, REYNOLDS NUMBER, SKIN FRICTION, BOUNDARY LAYER FLOW, STAGNATION POINT, LAMINAR BOUNDARY LAYER.

Subject Categories : Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE