If you are looking for a Tamil-language film with the same name,
However, that film is primarily in , not Tamil, though it is set against a Tamil backdrop (Tamil Nadu, especially the train journey to Chennai) and features several Tamil cultural references, songs, and dialogues mixed with Hindi. chennai express movie tamil
I think you might be referring to the 2013 Bollywood film starring Shah Rukh Khan and Deepika Padukone . If you are looking for a Tamil-language film