The core algorithm hasn’t changed since I introduced the damped sine (actually cosine) Expression component, just making it better. 
Wouldn’t it be nice if it worked with multiple rectangles? Took a few little tweaks to get the code in proper Grasshopper fashion, but it does now. Dimensions are obtained from the rectangles, which may be supplied by any means and need not touch each other. To demonstrate, there is a white “two rectangles” group that creates two side by side:
ripples_2019Jun08b.gh (61.2 KB)
Or you can use the internalized “3 rectangles”, imported from Rhino:
Baked and rendered as reflective copper material in Neon, R5:
Rhino file raytraced in R6:
