How to simulate pressure in an ideal gas simulation

[leibo]

Hello

I wrote a simple simulation of an 2D ideal gas, with elastic collisions. I wonder how should I simulate the pressure that is implemented on the particles in the box, by a piston with certain weight. it's easy to adjust the area of the box and the temperature of the particles which is proportional to the velocity squared, but I don't know how to change the pressure directly.

Thanks!

 

[mikeph]

If the gas is ideal then you don't have the freedom to simultaneously control the temperature, pressure, volume and particle number- you may dictate three parameters, and the fourth will then be fixed according to the ideal gas equation: PV = nRT. In short, you can't arbitrarily change the pressure without losing control of one of the other variables.

Having said that, I'm intrigued about your simulation- surely if the gas particles are colliding elastically, then that breaks one of the ideal gas conditions: that the particles are non-interacting.

 

[leibo]

If the gas is ideal then you don't have the freedom to simultaneously control the temperature, pressure, volume and particle number- you may dictate three parameters, and the fourth will then be fixed according to the ideal gas equation: PV = nRT. In short, you can't arbitrarily change the pressure without losing control of one of the other variables.

Having said that, I'm intrigued about your simulation- surely if the gas particles are colliding elastically, then that breaks one of the ideal gas conditions: that the particles are non-interacting.

Yes, you are right, it's a simulation of very simple real gas, rather than an ideal gas. I understand I can not decide the values of all 4 variables n,p,V,T. Yet, I can suddenly change T, with constant n, and V,P would change correspondingly to the equation. In the same way I want to be able to change the pressure P.

 

[mikeph]

How do you mean "suddenly change T"? Are you arbitrarily changing the average kinetic energy? As a result of this the temperature and pressure will both change (at constant volume). To control the pressure, you can change T and keep everything else constant.

 

[PJC01]

As a fellow scientist, I appreciate your interest in simulating pressure in an ideal gas simulation. In order to accurately simulate pressure, you will need to consider the kinetic theory of gases and the ideal gas law. The pressure in an ideal gas is directly proportional to the number of particles, temperature, and volume of the container. Therefore, to simulate pressure, you can adjust the number of particles in the simulation, the temperature of the particles, and the size of the container.

Additionally, you can also incorporate the concept of force and momentum into your simulation. The particles in an ideal gas will exert a force on the walls of the container, resulting in pressure. By calculating the forces and momentum of the particles, you can accurately simulate the pressure within the system.

Furthermore, you can also consider the weight of the piston in your simulation. As the weight of the piston increases, the pressure on the particles will also increase. This can be incorporated into your simulation by adjusting the gravitational force on the particles.

Overall, simulating pressure in an ideal gas simulation requires a thorough understanding of the underlying principles and equations. By incorporating the concepts of kinetic theory, ideal gas law, force, and momentum, you can create a more accurate and realistic simulation. I hope this helps in your research and experimentation. Best of luck!