Radial corrugation

Hi there,

I wondered whether someone could help me with a radial offset problem.

I am trying to corrugate a surface (with tubes in this case), and the strength of corrugation varies depending on the width of the surface, i.e. strongest corrugation at narrow waist, no corrugation at wide ends. I created a guide surface for the latter to gain more control over the corrugation strength.

My problem is that I am moving/translating/offsetting surface grid columns in one direction only (along x), because I don't know how to do it radially, how to control the vectors correctly. Does it need some sine/cosine function ?

Help would be much appreciated :)  I am attaching both Rhino and Gh file.

Regards,

Ben