int of f(x,t) from 0 to y on a 2D subdomain (used in the solving process)

TBE_Legend

Hi again,

Another method is to solve a PDE (the method comes from the Comsol Community Official Forum (thanks) )where my integral I is the solution of the PDE :

Add a PDE General Form Multiphysics in 2D geometry
Gamma = 0 0
f = Iy-f
(Don't forget to constraint I on a boundary to get a unique solution)

I = int_0^y f(x,y')dy'

That's it.

If you have a solution with the dest operator I am still interested.

--- In [email=COMSOL_Users%40yahoogroups.com]COMSOL_Users@yahoogroups.com[/email], "dokithonon" <thomas.doki-thonon@...> wrote:
>
> Hi Niklas, Hi Community
>
> Thanks for answering.
>
> The dest operator but it doesn't change the integration limits. In the Example of the model library the integration is performed on the whole domain and that is not what I'm trying to do.
>
> I've tried a projection coupling variable like this :
> Source: a 2d subdomain
> Destination: another 2d subdomain
> Expression: f*dest(y)
> This should compute int_0^y f(x,y') dy'
> This should be what i want to do but dest operator doesn't work in projection coupling variables (only in integration coupling variables)
>
> It works on a 1d subdomain because we can use integration coupling variables and then the dest operator is working.
> This works :
> Source: a 1d subdomain
> Destination: another 1d subdomain
> Expression: f*dest(x)
> It computes : int_0^x f(x') dx'
>
>
> Do you have any idea how I should use the dest operator ?
>
> Or any other methods to calculate this integral ?
>
> Thanks
> Best regards
>
> --- In [email=COMSOL_Users%40yahoogroups.com]COMSOL_Users@yahoogroups.com[/email], "niklas_rom" <niklas@> wrote:
> >
> > Hi, use the dest operator in the integrand. See an example here:
> > Model Library path: COMSOL_Multiphysics/Equation-Based_Models/integro_partial
> >
> > best
> > Niklas Rom, COMSOL, Inc.
> >
> > --- In [email=COMSOL_Users%40yahoogroups.com]COMSOL_Users@yahoogroups.com[/email], "dokithonon" <thomas.doki-thonon@> wrote:
> > >
> > > Hello,
> > >
> > > I have a subdomain in the plane xy in this subdomain I have f(x,y) which is an expression. The subdomain is squared ( x varies from 0 to a and y varies from 0 to b).

> > > I want to calculate at each point of the subdomain the integral I : I(x,y)=int_0^y f(x,y) dy (Integral of f from 0 to y)

> > > This integral should have a different value for any x,y coordinates.

> > > I know how to calculate this integral from 0 to b using Projection Coupling variables but i didn't manage to calculate it from 0 to y.

> > > ( I know that it is possible to do it with matlab in postprocessing but i need this value during comsol resolution)

> > > Does any of you have an idea ?
> > >
> > > Thanks a lot.
> > > Best regards.
> > >
> > > Thomas Doki-Thonon
> > >
> >
>

Here is the link mentioned by  dokithonon http://www.comsol.com/community/forums/general/thread/439/