Is there a synonym for open other than dilate that describes the process of spreading open from a central point?
For example, when fire burns a hole in a piece of paper what would the paper be said to be doing? Or when a whirlpool begins to form, is there a word that describes the process of the water being drawn apart? And also what about the action of a camera shutter?
For all of these examples open would technically suffice because readers already have a grasp of these objects' mechanisms and there is no need for further explanation. But if I am trying to describe something new with which the reader has no previous familiarity, such as a futuristic machine, then open no longer adequately conveys my meaning without additional qualifying words or descriptions. We are used to opening things such as doors or boxes or drawers that involve either a hinge mechanism or some variation of two usually linear objects drawing apart from each other, and if I use this word I feel that I will have to struggle against these connotations.
Dilate perfectly captures what I am trying to describe but I do not want to use it because it is traditionally restricted to the action of an eye's pupil or some other sphincter and therefore may not come across well with readers.
I understand that there may be no other single word for this action but I wanted to put the question out there in case some rare or obscure word does exist.
Note: I prefer a single word substitute, but I am not opposed to suggestions of words that may be paired with open, such as spread or draw.
So far there are two instances in a novel I am writing where I have needed a word to describe this motion. One example involves a wall opening, and the other involves a window opening. In both cases only a portion of the wall or window "retract" into themselves to create a hole or opening, and this without any noticeable bunching resulting around the edges.
Up ahead the right wall ______ into an archway and Madeline hurried through.
She was surprised when the glass ______ around her fingers, exposing them to the rain.
It is a futuristic story where the walls and even windows are constructed from intricate biological machines which permit them to morph into various shapes seamlessly. But it is not the mechanism that I wish to describe, it is the motion, which is why I thought it unnecessary to digress into the mechanical minutiae. Dilate describes the motion.