Induced drag of ground effect-vehicle

[Jurgen M]

Model ground effect-vehicle shape like on picture fly above flat surface like floor sports hall or ice, wing end plates and trailing edge is so close to the ground(1mm) we can assume airlfow under the wing is zero and has stagnation pressure("100% ground effect").
How to calculate induced drag?

(Dont debate about stability,tail/rudder will fix this.I want analyze induced drag only for wing)

Here is some models

 

[Baluncore]

How to calculate induced drag?

If there is no flow around the tip of the wing, then how can there be an induced drag ?

 

[jack action]

How would you calculate the drag of a bump, of the same shape and size, on the same flat surface, which has actually no air flow under it? An object moving in a static fluid is the same as a static object within a moving fluid.