How to change nostril flow

   The following Yogai techniques were described by Yoga guru, Swami Sivananda, in his book Kundalinii Yoga (Sivananda, 2005). From these, the only technique explored in scientific studies has been switching the nostril by adopting lateral postures (Mohan M. S., 1991). Note that the majority of these techniques are based on the body: some of them are fairly intuitive, such as blocking the decongested nostril, while others require long-term yoga techniques that must be practiced thoroughly before they can have a measurable effect of the nadis.
The following exercises are for changing the flow from Ida to Pingala. Select any one of the methods that suits you best. For changing the flow from Pingala to Ida, just do the same exercise on the opposite side:
1. Plug the left nostril with a small piece of cotton or fine cloth for a few minutes.
2. Lie down on the left side for ten minutes.
3. Sit erect. Draw the left knee up and keep the left heel near the left buttock. Now press the left arm-pit, Axilla, on the knee. In a few seconds the flow will be through Pingala.
4. Keep the two heels together near the right buttock. The right knee will be over the left knee. Keep the left palm on the ground a foot away and let the weight of the trunk rest on the left hand. Do not bend at the elbow. Turn the head also towards the left side. This is an effective method. Catch hold of the left ankle with the right hand.
5. The flow of breath can be changed by Nauli Kriya also.
6. There are some who are able to change the flow by will.
7. Place the Yoga Danda or Hamsa Danda (a wooden stick of about 2 feet in length with a rest of the shape of U at one end) at the left arm-pit and lean on it by the left side.
8. The most effective and instantaneous result is produced in changing the flow through Khechari Mudra. The Yogi turns the tongue inside and blocks the air passage by the tip of the tongue.
    The above exercise is intended for general regulation of breath […]. A knowledge more secret than the science of breath, a friend more true than the science of breath, has never been seen or heard of. Friends are brought together by the power of breath. Wealth is obtained with comfort and reputation through the power of breath. The knowledge of the past, present and the future and all other Siddhis are acquired and a man reaches the highest state, by the power of breath.