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Computer_3_09

# Computer_3_09 - ILBLI window to make the appropriate...

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Computer Assignment #3 We wish to analyze the viscous flow over the top surface of an NACA 4412 airfoil at 1 deg. AoA moving at 10 m/sec. in air at STP. The chord is 0.5152 m. Again, you can use the Vortex Panel Method in the engapplets Web site to calculate the inviscid flow. If you did it correctly for the WALZ method, you can use it here also. From that solution, you need the surface velocity distribution on the upper surface: s,U(upper) . Select and copy this file. This will be the edge velocity distribution for the boundary layer calculation. Use the ILBLI code under Boundary Layer Applets + Convection in the engapplets Web site to calculate the boundary layer flow. You can use the WALZ method to generate suitable “initial” conditions for the numerical method at a small value of x/L (say x/L = 0.05). Run the WALZ method for this flow as before. Then, under File select Launch and pick Launch ILBLI at about x/L=0.05. Now, you must carefully go through the input in the lower panel in the
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Unformatted text preview: ILBLI window to make the appropriate choices for the items under: Fluid Properties, 2) Reference Properties, 3) Surface Characteristics and 4) Calculation Parameters . In particular, you must carefully choose Δx and Δy and N and M. Choose Δx (by choosing N) as approximately the initial boundary layer thickness. Choose Δy by putting about 20 points across the initial boundary layer thickness. Choose M such that you have a high enough computational region by the end of the calculation. You have a good estimate of the final (either at the TE or separation point if separation is predicted)value of the boundary layer thickness from your earlier WALZ calculation for this problem. Leave the last item as the Default value. That controls laminar to turbulent transition, and we will do this assignment as a purely laminar flow. Compare your results to those from the WALZ method....
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