Is tensor flow library work off line in android for face recognition?
Yes, you can use TensorFlow Mobile offline. If the model is growing at exponential speed and should retrain every hour, then the on-devise computation is too much for your mobile devise to support. Whereas, if your model is trained once and used forever or retrained occasionally, then you can use your face-recognition model on-devise.
Check here https://www.tensorflow.org/mobile/mobile_intro#mobile_machine_learning_and_the_cloud for more information.