One thing is certain: the lead swimmer is NOT "pulling along" the drafting swimmer. The draftee may affect the leaders wake, but as emmett suggested, if anything it might add a fairing effect and actually aid the lead swimmer.
Here's a simple experiment we did in a fluid mecanics lab in college. We had two cylinders of equal diameter one directly in front of the other in a wind tunnel. We measured the drag on each cylinder as the trailing cylinder was moved further back. Basically the trailing cylinder got the best draft benefit very close to the the front cylinder (maybe 3D or so?), but I don't think the lead cylinder's drag was affected much if at all.
One thing is certain: the lead swimmer is NOT "pulling along" the drafting swimmer. The draftee may affect the leaders wake, but as emmett suggested, if anything it might add a fairing effect and actually aid the lead swimmer.
Here's a simple experiment we did in a fluid mecanics lab in college. We had two cylinders of equal diameter one directly in front of the other in a wind tunnel. We measured the drag on each cylinder as the trailing cylinder was moved further back. Basically the trailing cylinder got the best draft benefit very close to the the front cylinder (maybe 3D or so?), but I don't think the lead cylinder's drag was affected much if at all.
