COMSOL Multiphysics™

postint
For time-dependent problems, the variable t can be used in the expressions ei. The
value of t is the interpolation time when the property T is provided, and the time
for the solution, when Solnum is used. Similarly, lambda and the parameter are
available as eigenvalues for eigenvalue problems and as parameter value for
parametric problems, respectively.
Examples
Compute the integral of the solution to Poisson’s equation on the unit disk using
weak constraints. Use weak constraint to obtain accurate flux.
clear fem
fem.dim = {'u' 'lm'};
fem.geom = circ2;
fem.mesh = meshinit(fem);
fem.shape={'(2,''u'')' 'shlag(2,''lm'')'};
fem.equ.c = {{1 0}};
fem.equ.f = {{1 0}};
% make shape function for u active on subdomain
fem.equ.shape={1};
fem.bnd.weak = {{'test(u)*lm' 'test(lm)*(-u)'}};
% make shape functions for u and lm active on boundary
fem.bnd.shape={[1 2]};
fem.solform = 'general';
fem.xmesh = meshextend(fem);
fem.sol = femstatic(fem);
postint(fem,'u')
Verify that the integral of the source term in Poisson’s equation on the unit disk
cancels the integral of the flux over the boundary. To have access to the variables f1
and ncu1, we need to use solution form
postint(fem,'f1')
postint(fem,'lm','edim',1)
The variable ncu can also be used to compute the flux, but it is much less accurate.
postint(fem,'-ncu1','edim',1)
Compatibility The properties Context, Cont, and Contorder are obsolete from FEMLAB 3.0.
The property Variables has been renamed to Const in FEMLAB 2.3.
See Also
posteval
344 | CHAPTER 1: COMMAND REFERENCE