You have to squeeze the air out of your mouth with your tongue, just like gargling, and squeeze the last sip of water out of your mouth (not by air).

While pushing water, the nasal cavity does not work;

Try to push the air with your tongue, one by one, and feel the strength and uniformity of the push. You can practice on the flute after you are familiar with it, and let the gas push the flute.

If you can push the flute evenly with your tongue, you can practice inhaling at the same time.

While inhaling, push your tongue outward. Be sure to do it at the same time! This is a reverse action, which needs more practice to coordinate. That's the hard part.

You will gradually find-interesting!

Key points of circular ventilation-the space in the mouth should be large, like peeled eggs, but you can't drum your cheeks. Then the tongue should be strong.

The empty push is above 1 second, and it will take some time to integrate this short flute sound into the normal flute sound.