Velocity direction of inlet boundary

[popstar0426]

Hi: Consider the flow around an airfoil with attack angle 8 degree, only two boundary conditions: Adiabat_Fix (wall of the airfoil) and Char (farfield) are defined. Question is that: How can I specify the velocity direction to simulate the 8 degree attack angle? I noticed the input as below: Viscous Boundary Conditions - Used only for viscous cases Mach_free_stream: Mach number of free-stream flow nx_free_stream: normalized x-component of free-stream flow [unit normal component] ny_free_stream: normalized y-component of free-stream flow nz_free_stream: normalized z-component of free-stream flow

Does "nx_free_stream" and "ny_free_stream" define the velocity direction of the farfield?
However, when I define the input file like this:
-----------------------------------

Boundary conditions

==== Viscous ==== fix_vis 0 // 0: Sutherland's law, 1: Constant viscosity Mach_free_stream 0.1 nx_free_stream 0.99756405 ny_free_stream 0.06975647 nz_free_stream 0. Re_free_stream 60000 L_free_stream 1. T_free_stream 300 T_wall 300 Mach_wall 0. nx_wall 1. ny_wall 0. nz_wall 0. T_wall 300 Mach_c_ic 0.1 nx_c_ic 0.99756405 ny_c_ic 0.06975647 nz_c_ic 0.

The attack angle is still zero. Is there any wrong?

Best regards!

[mlopez14]

No, you have the right idea. Just to make sure, what happens as ny goes higher? Is the resulting force in the y direction zero?

[popstar0426]

Hi: I attached a figure to describe the nx and ny. What do you mean "the resulting force"?

Best regards!

[popstar0426]

Hi: Now I understand your comments. I will increase ny and check it again.