Back to basics: bubbles in a syringe

[rwooduk]

This started out as a model in which the system is close to thermodynamic equilibrium and gradually changing within a syringe. Now it turns out that the desired idealized model should be something like a bubble in an infinite ocean of water containing dissolved air in which the dissolved air concentration at infinity is a fixed value and the pressure at infinity is being oscillated. We would be looking for the oscillatory steady state (in which velocities, concentrations, and pressures are varying sinusoidally). This is quite a stretch from a system close to thermodynamic equilibrium.

I agree, you are quite right, I was trying to compare the two, taking the syringe as a simplified version of the ultrasonic system, which I now realize is inaccurate. But I first needed to understand the syringe system. Basically I was trying to assess if any vaporisation could occur for the syringe system with a view to understanding more the effects of vaporisation for the ultrasonic system.

 

[Chestermiller]

I agree, you are quite right, I was trying to compare the two, taking the syringe as a simplified version of the ultrasonic system, which I now realize is inaccurate. But I first needed to understand the syringe system. Basically I was trying to assess if any vaporisation could occur for the syringe system with a view to understanding more the effects of vaporisation for the ultrasonic system.

The amount of water vapor in the bubbles is going to be changing, although it is not clear (until the problem is fully modeled) how important this effect will be.

 

[rwooduk]

The amount of water vapor in the bubbles is going to be changing, although it is not clear (until the problem is fully modeled) how important this effect will be.

It does change and is often related to the structural stability of the bubbles (which adds another element to the situation). A more unstable bubble such as would be seen at high acoutic pressures or with increased acoustic streaming can increase rectified diffusion. It's important for sonolytic process where polyatomic vapours can act to reduce the bubble temperature due to their higher heat capacity. But I'll stop there in an effort to not move further away from the OP. Thanks again.