The white lines are the streamlines which intersect the plate and are called stagnation streamlines. You can vary the angle of the plate by using the slider below the view window or by backspacing over the input box, typing in your new value and hitting the Enter key on the keyboard. On the right side of the simulator is a gage with some buttons and some sliders. You can change the location from side to side by using the slider located below the gage, and you can change the location up and down by using the slider to the left of the gage. You select which variable to display by using the white buttons labeled Velocity, Pressure, or Smoke.
Smoke causes green particles to be released from the probe.
The blue buttons control the type of display shown in the left view window. You can further investigate the effect of airfoil shape and the other factors affecting lift by using the FoilSim II Java Applet. You can also download your own copy of FoilSim to play with for free. Changes in Speed or Direction Lift is a force generated by turning a flow. The direction of the lift force is defined to be perpendicular to the initial flow direction.