For the purposes of this challenge, a polyphthong is defined as a contiguous slice of a String, that only contains vowels, and has length at least 2. Given a non-empty String as input, your task is to output all the polyphthongs it contains.
"abeoic" has the following contiguous slices (space-separated):
a b e o i c ab be eo oi ic abe beo eoi oic abeo beoi eoic abeoi beoic abeoic
Removing those that contain anything other than vowels, or have length smaller than 2, we get our desired polyphthongs:
eo oi eoi
Your submissions must abide by the following rules:
You can choose either lowercase or uppercase for I/O, but the output case must match the input case.
The vowels are
aeiou(for lowercase) and
Yis not considered a vowel.
The input will only contain printable ASCII.
If a polyphthong appears multiple times, you may choose to output it only once or output all its occurrences.
Any reasonable I/O format and method is allowed (lists of characters are also fine, for both input and output).
Input -> Output (lowercase) r67^^()*6536782!87 ->  programming puzzles and code golf ->  aaand... i won! -> ['aa', 'aa', 'aaa'] abeoic -> ['eo', 'oi', 'eoi'] yah eioo ala -> ['ei', 'io', 'oo', 'eio', 'ioo', 'eioo'] @yabeeeayio__e -> ['ee', 'ee', 'ea', 'io', 'eee', 'eea', 'eeea'] 0ioen0aaiosnjksd -> ['io', 'oe', 'aa', 'ai', 'io', 'ioe', 'aai', 'aio', 'aaio']
Note that for test cases 3 and 6, you may output
'ee' respectively only once (See the fourth rule).
This is code-golf, the shortest submission in bytes in every language wins!