Predefined rigid body movement in a laminar flow

Hi,

I want to model a predefined rigid body (cross-section of a bridge deck) movement in a laminar fluid flow. The deck should be moved in a harmonic oscillation (heaving or pitching) at a specific amplitude and frequency (after which I want to analyze the forces acting on the deck). My problem is how do I go about achieving this predefined motion? I'm new to COMSOL and I've tried some tutorials and reading topics on this forum.

My first approach was to use the laminar flow physics. But I could not get a moving boundary, do I need to add some physics? Like a moving mesh?
Or should I use the fluid-structure-Interaction module? This seems like a little overkill to me, since I do not want to model a deforming structure...
Or something else?

I would very much appreciate some advise on which approach to take!

Thanks,
Maria