Flow Air from Low to High Pressure Tanks

If a suitably sized air compressor is paced between the tanks, then yes, you can cause the flow of air from the low pressure tank to the high pressure tank.

Yes the air will flow from a low pressure tank to a high pressure tank if the actual pressure of the low tank is higher than that of the HP tank (the pressure in any tank is not determined by its pressure capacity)

If the two gauges in the drawing are the same (range) the flow will be from high to low if not restricted.

Run the movie backwards.

You used the word "flow". No, it will not flow from low to high pressure. You CAN pump from low to high pressure if your pump can generate an output pressure higher than the high pressure tanks pressure.

If the low pressure nozzle is inserted into the high pressure nozzle, and a check valve is installed in the low pressure line and the lp line is terminated close to hp tank outlet with hole opening directionally sympathetic to the air flow stream, then a neg pressure area may be generated at the lp nozzle hole outlet facilitating an introduction of lp originated air into the hp air stream, a process known as suction feeding...

What do you think, and why?

Sure! No problem. All you have to do is elevate the low pressure tank to a high enough altitude to overcome the pressure differential between the high and low tanks. Sort of a gravity flow system.

Or heat the bejesus out of the low pressure tank with a torch and cool the high pressure tank with liquid CO² to overcome the pressure differential.

Really, come on now. Did you really have to ask the question, and remove all doubt?

Yes it possible if air in both tanks are in liquid phase.

1 - withdrew liquid air from the bottom of tank- A and let it flow through an evaporator coil and return back to the top of the same tank. return air in gaseous phase will gradually creates high pressure at the top of tank -A

2 - release air in gaseous phase from the top of tank - B. this process will decreases pressure for Tank - B

3 - after some time pressure in tank - A will be higher than pressure in tank - B

4 - open the valve in between tank -A and tank - B ( bottom connection ) , then liquid air will flow from tank -A to tank -B

this process is done for recharging liquid oxygen tanks with high pressure through delivery truck with lower pressure.

yes, it is quite possible and very easy.

I found a way to do this while working on my perpetual motion machine in 1976.

I am very wealthy now ever since I found a method to turn tin and lead into gold