On the Efficacy of ANSYS FLUENT in Predicting Transonic Flow Characteristics
Keywords:
ANSYS Fluent, Spalart-Allmaras model, Transonic flows, Multigrid, Shockwave, Shock-capturing technique, Upwind computational methodAbstract
Transonic flows have long been studied. Our focus for this presentation is on the efficacy of an industrial CFD package/codes to the limit of its acceptability. Many companies use ANSYS FLUENT as their computational package, therefore, there is a need to check the efficacy of FLUENT, a CFD package in simulating a transonic NACA4412 airfoil. The airfoil geometric properties employed were:
a) Angle of attach, α =50; b) Mach number, Ma=0.9; c) Chord length, c = 1.00m; d) the specific heat at constant pressure, Cp =1006.43J / (kg.K); e) the thermal conductivity, k = 0.242 W / (m.K) and f) the Spalart-Allmaras turbulence model usually reserved for aerospace application involving wall-bounded flows was used with: Ch1=0.1355; Ch2 =0662; Cv2 =07; Cv2 =0.3. A full Multigrid (FMG) initialization was used to obtain better initial field flow variables. The solution was calculated using the pressure based coupled solver of the Fluent Computational Fluid Dynamics (CFD) package. Force and Surface monitors were used to check the solution convergence. The near-wall mesh resolutions were checked by plotting the distribution of the y+ values. With a Mα∞ = 0.9 (transonic), a fairly strong shock was observed near the trailing edge (x / c = 0.87) on the upper (suction) surface of the airfoil. Reynolds number, Re based on the cord length of the airfoil was calculated to be 1.89 × 107 The convergence history of the airfoil performance parameters such as the average of surface vertex velocity, drag, lift, moment, pressure coefficients, etc. were computed.
