Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Adding a Faxen Force on Stokes drag force in Particle Tracing Module

Please login with a confirmed email address before reporting spam

Hi everyone,

I am trying to use the particle tracing module with a non-uniform laminar flow in a channel. I am using "Drag Force" to trace the particles' motion. However, the Stokes force is defined without the Faxen Force in Comsol.
(oi46.tinypic.com/28c33nl.jpg)

I am wondering how I can add the Faxen Force on the equation. Is there already built-in physics module for Faxen Force?

Thanks a lot,
Damla

1 Reply Last Post Feb 12, 2013, 4:29 p.m. EST
Fabrice Schlegel COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Feb 12, 2013, 4:29 p.m. EST
Dear Damla,

This force can be added to the Particle tracing physics by right clicking it and selecting "Force". The force components can then be added as:
Fx=pi*spf.mu*fpt.dp^3/8*(uxx+uyy)
Fy=pi*spf.mu*fpt.dp^3/8*(vxx+vyy)

An example is included in the attached model. Please note that the velocity field needs to be discretized using second order elements in order to evaluate this force (as done in the attached model). By default, COMSOL uses first order elements.

Using the defaults first order elements could also be done but it would require additional modifications.

Best Regards,
Fabrice Schlegel, PhD
COMSOL Technical Support Team
Dear Damla, This force can be added to the Particle tracing physics by right clicking it and selecting "Force". The force components can then be added as: Fx=pi*spf.mu*fpt.dp^3/8*(uxx+uyy) Fy=pi*spf.mu*fpt.dp^3/8*(vxx+vyy) An example is included in the attached model. Please note that the velocity field needs to be discretized using second order elements in order to evaluate this force (as done in the attached model). By default, COMSOL uses first order elements. Using the defaults first order elements could also be done but it would require additional modifications. Best Regards, Fabrice Schlegel, PhD COMSOL Technical Support Team

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.