Menu

Discussion Forum

New Discussion
Filtrer

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 The information provided may be out of date.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 get a value of dependent varible with time at boundaries?

Posted 16 janv. 2011, 12:00 UTC−5 Parameters, Variables, & Functions Version 3.5a 4 Replies

GaneshM Battery Modelling
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi..

I need to get a value of dependent variable w.r.t time at boundaries . How can I write the expression for it?

for example, in 1D phi1 and phi2 are dependent variables and function of both(x,t) in subdomain 1 containing 2 boundaries.

I have to get the values of phi1 at boundary 1 with function of time. Similarly, phi2 at boundary 2 with function of time.

How to define V_cell= phi1( at boundary 1)-phi2(at boundary 2) at each time ?


thanks

regards
Ganesh

4 Replies Last Post 21 janv. 2011, 10:54 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 16 janv. 2011, 12:28 UTC−5
Hi

check the KB on the main site, ther are a few entries on time derivatives therin, I believe you should get your reply from there ;)

And many things of V4 are still applicable for 3.5a
--
Good luck
Ivar
Hi check the KB on the main site, ther are a few entries on time derivatives therin, I believe you should get your reply from there ;) And many things of V4 are still applicable for 3.5a -- Good luck Ivar
GaneshM Battery Modelling
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 21 janv. 2011, 03:36 UTC−5
Hi Ivar,

I have tried to get the values of dependent variables wit time at boundaries using boundary integration variables.

I have defined phi100 = phi1 at boundary 1
and phi201 = phi2 at boundary 2 in boundary integration variables


will they give the values of dependent variables at boundaries each time?

is this the correct way to get the values at each time?

thanks

ganesh
Hi Ivar, I have tried to get the values of dependent variables wit time at boundaries using boundary integration variables. I have defined phi100 = phi1 at boundary 1 and phi201 = phi2 at boundary 2 in boundary integration variables will they give the values of dependent variables at boundaries each time? is this the correct way to get the values at each time? thanks ganesh
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 21 janv. 2011, 09:12 UTC−5
Hi

If you do an integration over a boundary (typically a 2D surface in 3D mode or a line/edge in 2D mode) then you are getting the integrated (summed) value over each element *dx*dy (2D) or times dx (1D). So a heat Flux Q[W/m^2], in 3D gives you. Note: COMSOL is integrating by "advanced" summation with loca higher order polynomial fitting.

Q_tot [W] = integration_overboundary of ( Q[W/m^2] *dx*dy )

If you have done a parametric saweep or a time series (transient analysis), when you plot this you get the Q_tot versus time or Parameter values

--
Good luck
Ivar
Hi If you do an integration over a boundary (typically a 2D surface in 3D mode or a line/edge in 2D mode) then you are getting the integrated (summed) value over each element *dx*dy (2D) or times dx (1D). So a heat Flux Q[W/m^2], in 3D gives you. Note: COMSOL is integrating by "advanced" summation with loca higher order polynomial fitting. Q_tot [W] = integration_overboundary of ( Q[W/m^2] *dx*dy ) If you have done a parametric saweep or a time series (transient analysis), when you plot this you get the Q_tot versus time or Parameter values -- Good luck Ivar
GaneshM Battery Modelling
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 21 janv. 2011, 10:54 UTC−5
Hi.. thanks for the reply..

I used this boundary integration in 1D geometry. I think it will consider the value at that point (1D)on boundary.

so, it represents the value of phi1 at that point at each time. isn't it?



thanks
ganesh
Hi.. thanks for the reply.. I used this boundary integration in 1D geometry. I think it will consider the value at that point (1D)on boundary. so, it represents the value of phi1 at that point at each time. isn't it? thanks ganesh

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