In my addons Addon. Produces almost infinite many time-varying geometries with functions I have realized such deformations individually using different functions.
I made it for Geometry, indexed and non-indexed BufferGeometry.
Try it out: https://hofk.de/main/threejs/sandbox/
Maybe you can take something from there.
e.g.
https://github.com/hofk/THREEf.js/blob/7b76151f112779f48f16878c571541d44b00a70b/THREEf_90/THREEf.js
line 1994, 2052
https://github.com/hofk/THREEp.js/blob/6a268d2eafa7782ce267c5d8e6c5e0c4c4d81fe5/THREEp_90/THREEp.js
line 2075, 2158, 2221