knock about vs thrash about

knock about

verb
  • To move or roam around aimlessly. 

  • To be mislaid in a place. 

  • To engage in a relaxing activity in a place; to hang around in. 

  • To be present at or inhabit a certain place. 

  • Often followed by with: to spend time companionably; to hang around. 

  • To live an unconventional life. 

  • To hit (someone or something) all over repeatedly; hence, to behave violently towards or mistreat (someone or something). 

thrash about

verb
  • to move unpredictably and often violently, usually unaware 

How often have the words knock about and thrash about occurred in a corpus of books? (source: Google Ngram Viewer )