effusion vs welling up

effusion

noun
  • Process of gases passing through a hole or holes considerably smaller than the mean free path of the gas molecules. 

  • An outpouring of speech or emotion. 

  • The seeping of fluid into a body cavity; the fluid itself. 

  • A liquid outpouring. 

welling up

How often have the words effusion and welling up occurred in a corpus of books? (source: Google Ngram Viewer )