[irevo]

I am trying to simulate a flow past a wing, and for only pitch or only yaw, it is simple to adjust the vector components in the inlet.

For example, a 10 degree AOA will result in
x component = 0.984808 (cos10deg)
y component = 0.173648 (sin10deg)


However, I am trying to get the flow to do both a 10 degree pitch as well as a 30 deg yaw but i am having some trouble trying to resolve the components.

[shereez234]

Originally Posted by irevo

I am trying to simulate a flow past a wing, and for only pitch or only yaw, it is simple to adjust the vector components in the inlet.

For example, a 10 degree AOA will result in
x component = 0.984808 (cos10deg)
y component = 0.173648 (sin10deg)


However, I am trying to get the flow to do both a 10 degree pitch as well as a 30 deg yaw but i am having some trouble trying to resolve the components.

You figure out the pitch by looking at it from the side view. Using basic trigonometry you are able to tell that the x component should take the cos of theta, and the y component should take the sin of theta. From this point start looking at it from the top view as what you have now is a velocity vector that looks diagonally going up. Now you have to rotate it around the vertical axis to create the yaw angle or sideslip. From this point figure out if psi angle needs to take the cos or sin component.



For verification plot a 3d stream line and look at it form pure side perspective and top perspective. Do some analysis and let's see where you get


Alternative option is to do pure rotations of the wing/geom rather than wind-velocity vector and in flight dynamics it is phi-theta-psi angles we need to manipulate.

[PedroS]

Hi all.
I am using the same principle to insert an inlet boundary condition with a velocity direction different from the perpendicular to the inlet surface.
I am using a mass flow inlet and I want the inlet to be at 22.5º. I am inserting an X flow component of cos 22.5º and a Y flow component of sin 22.5º. But the resulting velocities are much higher (~2 or 3 times) than the ones calculated with the relation between the inlet area and the flow rate. Is this really the right way of inserting the flow components?
P.S.: If I use a CAD model with the complete inlet geomety (with the correct orientation and no need to specify the flow components) the resulting velocities are the ones that where expected by the v=Q/A formula.

[PedroS]

I ended up realizing it actually makes sense. When I specify the mass flow in an inlet with a different orientation from the real one, the mass flow is incorrectly specified. As the mass flow is determined by the velocity normal to the inlet, a different inlet orientation results in incorrect velocities.