What is the Differential Equation for Airflow in a Balloon?

[Hansemannchen]

I have a problem. The task is to develop an differential equation of the airflow of a balloon. I know that it is dependent on the volume and pressure. But I can't get a good differential equasion. Can someone help me?

[Thread moved from the technical forums, so no Homework Help Template is shown]

 

[BvU]

Hello Hans, !

Here at PF we consider 'tasks' as homework, and for homework we require you post your own attempt at solution before we are allowed to help.

Anyway, helping is difficult if the problem isn't described clearly: 'airflow of a balloon' is not enough to describe what is going on. What air ? Going in, or out, or perhaps around while moving upwards ?

 

[Hansemannchen]

Oh sorry I am new to this forum and I may made a mistake :D The task or homework is to discribe the volume of the balloon and not the airflow. And I tried to solve this a few times but I can't come up with a suitable solution.

 

[hutchphd]

Seems to me you will need to some know the characteristics of the efflux (back pressure vs flow rate). Also you need to understand rubber and how the tension is related to radius. What is the variable you will use to characterize the system?
Assume a spherical balloon ...

 

[kuruman]

Have you researched the subject on the web? Try "Inflating a balloon" and see what pops up (no pun intended). Others have tried the same thing as you and you might profit from their efforts.

 

[BvU]

The task or homework is to discribe the volume of the balloon and not the airflow.

Still incomplete: steady state (--no--) ?, during inflation?, during deflation ?
Please post a complete problem statement -- if you have one, it should help you too !

And I tried to solve this a few times but I can't come up with a suitable solution.

Post your best shot !