Menu

Discussion Forum

New Discussion
Filtern

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 The information provided may be out of date.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.

How to set initial velocity in level-set method two phase flow for one phase

Posted 27.02.2013, 15:03 GMT-5 Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.3 4 Replies

Osameh Ghazian
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi guys,
I am trying to set the initial velocity for a droplet as fluid 1, how can I set an initial velocity for the bulk of fluid (for example the the continuous phase or the drop) in level set method?
I am trying to model the impact of the drop on the surface, I wanna increase the impact velocity.
4 Replies Last Post 13.03.2013, 21:57 GMT-4
Ryan McDevitt
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 27.02.2013, 17:12 GMT-5
You can add a second "Initial Values" node from the model tree. This allows you to select the domains containing the continuous phase, and assign a separate initial condition.
You can add a second "Initial Values" node from the model tree. This allows you to select the domains containing the continuous phase, and assign a separate initial condition.
Osameh Ghazian
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 27.02.2013, 17:43 GMT-5
thanks for your reply. But I think initial value is different from initial condition.
initial value could be anything just for the solver to initialize the problem. but initial condition means exact value at t=0.
there is no initial condition in COMSOL. I think we have to it manually.
thanks for your reply. But I think initial value is different from initial condition. initial value could be anything just for the solver to initialize the problem. but initial condition means exact value at t=0. there is no initial condition in COMSOL. I think we have to it manually.
Ryan McDevitt
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 27.02.2013, 18:37 GMT-5
"Initial Value" serves as an initial guess for a stationary solver or as an initial condition for a transient solver. For reference you can check page 526 of the User's Guide.
"Initial Value" serves as an initial guess for a stationary solver or as an initial condition for a transient solver. For reference you can check page 526 of the User's Guide.
Osameh Ghazian
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 13.03.2013, 21:57 GMT-4
Thanks for you reply.
But if you change the initial value of velocity, it doesn't converge, because the phase initialization solver for level-set is very sensitive to this initialization. It is not even possible to use a time step function for velocity to gradually increase it, cause the phase initialization in not time dependent.
Any idea how we can set an initial velocity rather than zero for one of the phases in level set method?
Thanks for you reply. But if you change the initial value of velocity, it doesn't converge, because the phase initialization solver for level-set is very sensitive to this initialization. It is not even possible to use a time step function for velocity to gradually increase it, cause the phase initialization in not time dependent. Any idea how we can set an initial velocity rather than zero for one of the phases in level set method?

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.

Suggested Content