Sign in to follow this  
WiredCat

Gas dynamic

Recommended Posts

Well i have some questions at this time:

please see this:

[media]http://www.youtube.com/watch?v=Igpsm1r6Jas[/media]



its a gas sim :P





Lets assume that one shining dot is actually two hydrogen atoms (H2)

first question: when this H2 collides with other H2 (please let it'll be a sphere [ex protone]), they repel each other BUT: can they just fly by without collision? or they collide like here:

[img]http://upload.wikimedia.org/wikipedia/commons/6/6d/Translational_motion.gif[/img] -- the 'atoms' collide like normal spheres



from [url="http://en.wikipedia.org/wiki/Temperature"]http://en.wikipedia....iki/Temperature[/url]



SO HOW DO THEY COLLIDE? LIKE NORMAL SPHERES OR THEY CAN JUST FLY BY THEMSELVES AND DO NOT COLLIDE AND CHANGE DIRECTION RAPIDLY? :) its really important question without this i cannot start simulating atoms



second question is: if we have a BOX like in first movie and we have not so many (now) gas molecues (so the pressure is 'low'). HOW DO THE MOLECUES POSITION IN THE BOX, i know one thing with temperature greater than 0 degrees they will be moving, but what with empty space ? THE GAS SHOULD FILL WHOLE BOX VOLUME but it has not enough atoms so how do the atoms behave there? in ex if we have 20 molecues (h2) does gas divide volume by 20 and one molecue is situated in 1/20 of box volume ? lol i guess not but how do atoms behave there





and last question: let's assume thet we have 2 molecules in box [almost vaccum there], when atoms (hydrogen molecues - H2) are close enough to each other they start to repel but what happens if they are far away from each other do they attract ? whats the name of this attract force ? is it equal to newton gravitational force like F=G ((mm)/r*r)








PLEASE HELP i am only a programmer not a physicist or chemist i am only interested in this kind of stuff and i just want to simulate those processes to have better knowledge lol :C

Share this post


Link to post
Share on other sites
It's been a while since I've studied the subject, but you can essentially treat the gas molecules (not atoms) as spheres. This should model the behavior of ideal gases.

The molecules start with a given speed and direction, mostly random. The greater the speed, the greater the 'temperature' of the gas. You should have them hit each other and bounce off. That's what gives gases their qualities.

The molecules don't distribute themselves evenly by design. It's the interactions and bouncing around that cause them to have an even average distribution over time.

In the case of two molecules in an empty box, they will just bounce around, only rarely hitting each other.

Try finding more information, not just here but at least in an introductory physics book. You can't make a simulation of a physical process without understanding the physical process you want to model.

Share this post


Link to post
Share on other sites
As for your last question:

for two particles, the attracting force is a mix of many different forces, most notably the "Van der Waals force". For most simple simulations, you don't need to worry about this. If you neglect this attracting force and model the atoms as sphere with a perfectly elastic collision, you have simulated an ideal gas, a good approximation of a real gas. The collision between the atoms is the same as between billiard balls. There are a lot of videos and websites about this, so feel free to search around.

Emiel

Share this post


Link to post
Share on other sites
one post shits another s0 two paricles can pass one particle but the ideal gas cant do this well i wont simulate ideal gas for my option ideal gas explodes with forec what you want so whats ideal gas do nyou want to produce it?

so if energy of rest will force some particle to go where he would not be anywhere (he wont be there because allforcenfore particle to go elsewhere) - so it's possible tyhat was a one question thankt you you didint learn me anything lol but i love you :* ideal ghas is like ideal weapon?:] oh ah shit I spilled my beer so who will won :PPPPPPPPP

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this