A Study on Wall Transport Processes in Turbulent Recirculation Flow

• Main Authors: WEI-SHUNG CHEN, 陳偉雄
• Other Authors: K.C.CHANG
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/23691961924359099917

碩士 === 國立成功大學 === 航空太空工程學系 === 83 === In calculating turbulent flow，the turbulent closure mod- els are often adopted by investigstors。It is well-known that the performances of low-Reynolds-number turbulence models are better than those of the conventional turbulence models incor- porated with the wall function formulas which bridge the no s- lip boundary condition at solid wall to flow region。 As a result，the low-Reynolds-number models have been wid- ely applied to simulate the problems of wall heat，mass trans- fer and so on。However these low-Reynolds-number models have been developed which can yield good predictions in boundary ayer flows，channels flows，fulley developed pipe flows 。 Hsieh and Chang，these low-Reynolds-number models are investigated。 Results show that these low-Reynolds-number mod- els fail to predict accurstedly in the neighborhood of reatta- chment points ，because these models adopted wall shear stress as a parameter Fm and F2。They are to develop a robust low-Re- ynolds-number turbulence model which can give correct predict- ion in the recirculating flow。 The influence of the eddy viscosity may be seriously on nonisothermal flow in heat or mass transfer predictions。 In the neighborhood of reattachment points where invariably produce hot spots。 Therefore ， an accurate prediction of in the near wall region for turbulent flows is required。 The numerical program is written on a staggered grid s- ystem。 The Navier-Stokes equation are approximated via the finite volume methods， SIMPLER algorithm and the convect- ive terms are treated by QUICK scheme of Hayase，and emplo- yed robust low-Reynolds-number turbulent model applied to Backword facing step flows。Simulation and discuss heat and mass transfer in the near wall regions。