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 The information provided may be out of date.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 an input variable that is the function of a valuable solved in the time dependent simulation?

Please login with a confirmed email address before reporting spam

Hi,

I am working with an elastic structure which was influenced by some known forces and an unknown force. This force (damping) is actually proportional to the velocity of a specific point on the structure. The initial condition is given in this case. Since the structure is deformed and moving under the influence of all the forces, Comsol can get the velocity of that specific point through simulation and therefore get that unknown force for that moment. And then it can goes on for the next time step with the calculated force. How can I set this input force? How can I set an definition of that unknown force with the velocity(changing with time) of that specific point?

Can you help me with this? Thanks soooooooooooo much!


Best,

Ting

2 Replies Last Post Jun 10, 2014, 7:32 p.m. EDT

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jun 10, 2014, 5:33 a.m. EDT
Hi Ting,

You can use 'at1', 'at2' or 'at3' to refer to a value at a specific point in your geometry (1, 2 and 3 refer to the spatial dimensions in your model). So for example if you have a 3d geometry and the displacement is given by u then you would find the X-component of the velocity at point (x,y,z) by at3(x,y,z,u_tX). This expression you can use to define your force.
Hi Ting, You can use 'at1', 'at2' or 'at3' to refer to a value at a specific point in your geometry (1, 2 and 3 refer to the spatial dimensions in your model). So for example if you have a 3d geometry and the displacement is given by u then you would find the X-component of the velocity at point (x,y,z) by at3(x,y,z,u_tX). This expression you can use to define your force.

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jun 10, 2014, 7:32 p.m. EDT
Thanks so much! :-)


Best,


Ting Zhou
Thanks so much! :-) Best, Ting Zhou

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.