# Module 2 - Cheryl Mulor

Journal Entry For
Module 2 - Ripples on a Pond

Screenshots from Revit - From the top and from the side to show the diminishing effect

Modelling approach

• I started by first creating a small grid to represent the pond. At first i forgot to chnaging the lacing method to cross product which made me run into some problems later but I quickly referred to video and made the needed changes
• I then created a point to represent the coordinate point of the pebble
• Then I calculated the distance between all the center points on the grid to the pebble point using the geometry node
• Then using the sine wave function, I was able to set the height parameter of the individual cylinders as a function of the distance between the placement point of each cylinder and the location where the pebble is dropped. I added number sliders for the base offset (to make sure that there will be no negative inputs for the cylinder height), number of waves and wave amplitude. Then to simulate the diminishing effect, I used a decay function of A*e^(-kx) where x is the distance betwen the pebble point and the center of placement points.
• I then loaded the cylinder mass into the revit project using the FamilyInstance.ByPoint
• In order to create the effects of a second pebble, I created another pebble point and followed similar steps after that up to adding the decay factor. Then I followed the principle of wave superposition (y(x, t) = A1 * sin(k1x ) + A2 * sin(k2x)) to simulate the effect of having two pebbles dropped in the pond. During all this, I made sure to use a small grid to help with making changes to variables like the base offset, the amplitude, number of waves etc. as fast as possible and when I was satisfied with the results, I changed it to a much larger grid to create the effect on the screen shot i posted above.

• Overall, I struggled a bit in the beginning but once I did research on the sine wave equation, everything made more sense and modelling on dynamo got much easier.