Jump to content
  • Advertisement
Sign in to follow this  
Icebraker

Scaling of Navier Stokes equations

This topic is 3806 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hello, I have implemented a Navier-Stokes solver for a fluid simulation. However, I have assumed that all measures are performed in SI-units. I am not sure how exactly I have to adapt the NS-equations so I can simulate smaller volumes, such as 10cmx10cmx10cm. Do I have to adjust the constants density and viscosity? Which part of the NS-equation do I have to adapt and how? Thanks, Icebraker

Share this post


Link to post
Share on other sites
Advertisement
So if I get you correctly I can just change the gravity, density and viscosity from meter to centimeter and get the simulation for a cm x cm x cm cube?

Share this post


Link to post
Share on other sites
Icebraker, I think you've got it right, but I will try to add some clarification.

The idea, introduce by the other responses, is that you can use whatever system of units you want, and the equations will work. They key thing is, you must not mix different units, e.g., if you have decided to model water and so your initial density values are for water at 20 degrees Celcius at sea level, and the density value is in kilograms per square meter, then if you change your mesh to be represented in centimeters, you MUST convert your density to be kilograms per square centimeter. Similarly, if you want your density to be represented using kilogram, then you must make sure your specific heat, used in the energy conservation equation bits, is defined in terms of kilograms, not grams. So, the rule is that everything must the exact same set of units, and you cannot mix kilo/deci/centi/etc...

If you have a mesh that is 1 meter wide and you decide that you really wanted it to be 1 centimeter, then you can use the same coordinates for your mesh...just now calling them centimeters, and it is the conversion of the physical coefficients and property values to centimeters that will cause the fluid to behave properly for the smaller volume.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!