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Flow over an Airfoil (NACA0012) with two blocks

 

Same setup as the single block sample problem, except that here the problem is solved with two blocks.

 

Computational Procedure

 

The computational domain in the single block problem was split into two overlapping blocks in the i direction. Consequently, each block contained 128 ´ 50 ´ 3 grid points. The first block encompasses the pressure (lower) side of the foil, starting at the tail end and ending at the leading edge. The second block encompasses the suction (upper) side of the foil starting at the leading edge and ending at the tailing edge. A close-up of this grid is shown in Figure P4.1. The block grid is supplied as PLOT3D mesh files. Initial conditions have to be provided and are done in the main input file.

 

The simulation type is basic CFD. The MUSCL scheme is used for spatial differencing and the Beam-Warming scheme used for time differencing. The problem is solved two-dimensionally in the i and j directions. (Note that, although no spatial differencing is done in the k direction, 3 grid points are still required in this direction as this is the minimum number of grid points allowed in any direction.). The Spalart-Allmaras model is used for the simulation with trip points on the surface of the blade; one each on the pressure and suction side.

 

Obtain the Files

 

Both mesh files and project input files can be accessed below. Remember to place the grid files in a subfolder with the set up file / airfoilm.

Setup file (foilm.afl)

Grid files (mesh0.PLOT3D, mesh1.PLOT3D).

 

Start the Simulation

 

Change the directory to the subfolder with the set up file. Start the simulation by

 

mpirun ¨Cnp 2 mpiaeroflo.exe < foilm.afl

 

 

 

 

Results

 

Figure P4.1(b) shows the Cp plot compared with the single block results of sample problem one.

 

(a)                                                                                                                                        (b)

Figure P4.1 (a) Mesh of the computational domain showing the two blocks, (b) Comparison of the coefficient of pressure, Cp, with experimental measurements

 

 

 

 

 

References

Harris, C. D., ˇ°Two-dimensional Aerodynamic Characteristics of the NACA 0012 Airfoil in the Langley 8-Foot Transonic Pressure Tunnelˇ±, NACA Technical Memorandum 81927, 1981.