Kundalini, when awakened will pass through Sushumna Nadi which passes through the spinal column. Sushumna Nadi extends from Muladhara Chakra to Brahmarandra or crown of the head. When Prana flows through both nostrils, then Sushumna Nadi is activated. You will have wonderful concentration and meditation. You can change the flow of breath in Ida and Pingala Nadis through concentration on the left and right nostril, through Khechari Mudra, etc
From Amrita Gita by Swami Sivananda, copyright The Divine Life Society. Swami Sivananda was a self-realized Master and a very practical Guru. Following His teachings can lead you to the Absolute.