summer OR olympics (or strongly preferred: both)
db.articles.find( { '$text' : { '$search' : "Summer Olympics" } } );
phrase "Summer Olympics"
db.articles.find( { '$text' : { '$search' : "\"Summer Olympics\"" } } );
phrase "wild flowers" OR Sydney
db.articles.find( { '$text' : { '$search' : "\"wild flowers\" Sydney" } } );
wild AND flowers
db.articles.find( { '$text' : { '$search' : "\"wild\" \"flowers\"" } } );
industry ANDNOT Melbourne ANDNOT Physics
db.articles.find( { '$text' : { '$search' : "industry *-*Melbourne *-*Physics" } } );