Calculating Diffusion Speed from Gas to Vacuum: How Do You Do It?

[zhaoxh]

Hi everyone,
I'd like to ask you a question. How to calculate the diffusion speed from a bulk of gas with density of n to vacuum? Thank you!

 

[edgepflow]

I would start with Fick's Law.

 

[Dickfore]

What is diffusion speed?

 

[zhaoxh]

What is diffusion speed?

actually, I want to consider the follow case. Consider that a bullet crosses a bulk of gas (desity=n), how to calculate the density evolution (with time) within the channel after the bullet goes through the gas.

 

[PJC01]

Hi there,

Calculating diffusion speed from a bulk of gas to vacuum involves several factors, including the gas density, temperature, and pressure. The diffusion speed can be calculated using the Graham's law of diffusion, which states that the diffusion rate is inversely proportional to the square root of the gas density.

To calculate the diffusion speed, you will need to know the molecular weight of the gas and the temperature and pressure at which the diffusion is occurring. You can then use the following formula:

Diffusion speed = √(8RT/πM)

Where:
R = Gas constant (8.314 J/mol K)
T = Temperature (in Kelvin)
M = Molecular weight of the gas (in kg/mol)

Once you have calculated the diffusion speed, you can compare it to the speed of other gases at the same temperature and pressure to determine the relative diffusion rates.

I hope this helps. Let me know if you have any further questions.

Best,