Can you recommend good breathing exercises to play woodwinds such as Flute and Bansuri.
Other than continual practice of these beautiful instruments, what are some breathing exercises to improve lung capacity?
First, a warning: the best way to improve breath control is by playing long-tones on the instrument. WIthout this, you don't hear the tone quality (or lack thereof) in relationship to breath control.
The next-best exercise is to train yourself to breath "down to the diaphragm" at all times, regardless of what you're doing. This means making your upper abdominal area expand first, rather than the top of your chest/shoulders. Don't worry about exact pressure or length of each exhalation yet.
Following that, do things like taking in a breath, getting your embouchure set (but no instrument involved), and exhaling for as long as you can while maintaining a set pressure. This helps minimize the rate at which you force air into/across the instrument as well as learning how to hold a note for a long time.
The most famous systematized breathing system is The Breathing Gym developed by the late Sam Pilafian and Pat Sheridan. A quick Internet search should give you plenty of sample exercises, some straight from this set and others adapted from it.
In terms of exercises to "improve lung capacity," a common exercise is to breathe in (either measured, over eight counts or so, or at your own pace) and hold it. But try to not "hold in" your breath by closing your throat; keep relaxed and leave your throat open. Stretch around, and every few seconds take a "sip" of breath to keep your lungs full. After a set period, slowly exhale (again, preferably measured over a determined number of beats to mimic a musical scenario).
But definitely be careful when doing this, and start slow and build up. I've seen plenty of learning musicians faint when they push themselves too hard.
Background: I studied flute from when I was young and through conservatory. Played professionally as a freelance classical musician for a little while afterwards.
With a little bit of distance I can say that much of what I was taught about breathing, and "lung capacity", etc. is nonsense. In fact I'm having trouble finding any credible information that suggests a person can alter their own lung capacity in any significant way by doing exercises for instance.
Instead I would focus on exercises on the flute (which any competent teacher should be able to help you with); these include basic long tones with all sorts of variations.
What you're trying to achieve is:
IMHO all of these are practiced and improved most efficiently by just playing (and practicing thoughtfully).
Also I would take any advice about how you should breathe or what a good breath should feel like with a big grain of salt. Our bodies are all quite different and flutists are not experts in anatomy.
I'm not sure where you're at in your woodwind "experience", but when I began playing clarinet and eventually flute, there were a couple things I did. Initially, when I had absolutely 0 breath control, I would lay on my back and place a text book or something with just a little bit of weight and just focus on controlling how I breathe in and out.
If you're already past that stage, I rather enjoy a little bit of meditation before playing anything musical. Days can get stressful and long, so in addition to helping me control my breath, it also helps me switch my mindset to something more open and music-ready. Besides that, I like to do a light jog every once in a while and just focus on breathing in time with my feet (or music if I have my earbuds). I used to be able to sing while doing a light jog, but it's been a while since I had the time or ability to do that.
If you're just trying to increase lung capacity, I would say take up jogging or some other form of cardio and spend that time focusing solely on your breath. (Or, to get started, lay on your back and place a textbook or something on your chest and just work on your breathing.) How you inhale, where the oxygen is flowing, how steadily you exhale, if you can control this process while you're body is under that kind of stress, etc.
I wouldn't over do it if you're not used to that, but if you run/exercise regularly, then you should be fine to just slow it down a tad and focus on breath. (And, like I said, I've heard that getting to a point where you can sing in time, on pitch, and with relative good tone while jogging lightly, it is very helpful.)
Hope that helps somewhat. Have a good day!