Please stop following the cult of the wingtip vortex and start to gain a better understanding of the flow around a wing. Stop reading if you encounter any of those myths:
- Pressure differences at the tip produce a flow around the tip, starting the vortex. Oversimplification!
- The tip vortex causes drag. Wrong!
Unfortunately, the web and much of unscientific literature is full of such myths. Authors with little understanding of the subject copy what they find without considering better sources.
If, however, you find statements like these:
- The wing sheds a sheet of vorticity along its span.
- The vortex strength behind a wing is proportional to the lift produced and inversely proportional to flight speed.
you have good reason to believe that the author knows his stuff. Read on!
In order to calculate the local flow speed and direction in the vicinity of the wing, all you need is the Biot-Savart law and apply it in a panel code. This calculates the influences of the vorticity on all parts of the wing at a specific location and adds them up.
Here is a list of other answers on Stack Exchange which you might find helpful in gaining a better understanding of aerodynamics and freeing yourself from the wingtip vortex myth:
- How does an aircraft form wake turbulence?
- Is a winglet better than an equal span extension?
- How can I get started on a winglet design?