I dont understand whats going on with the angle of attack?????
Dear whoever can help,
I have recently started using solidworks to model flow around an s809 aerofoil and my results for Cl and Cd are very different when i change the angle of attack by either changing the velocities in general setting or physically rotating the model!!!!!
I do not understand why this is the case.
If anyone has an answer or way to deal with it, or even suggestion as to which method i should use i would be very appreciative
aren't the values suppose to change with angle of attack? Or do you mean you get different values depending on how you change the angle of attack? If it is the latter it would not be surpising. While it is possibly a bit less convenient chanigng the velocity components to get the angle of attack you want it would be the preferred methond at least for low angles of attack as the meshes will be identical. Changing the angle relative to the global coordinate system will require a new mesh on each run, hence mesh induced errors may occur. Getting a fine enough mesh in either case is probably required to get close to experimental values. Still getting close values for the "Somers" series migh be a bit tricky as they are typically tailored to deal with some aspect of low to moderate R' numbers - like laminar separation bubbles. Not that I have checked it out in Flow Sim but I would not expect it to capture such phenomena.