COMSOL Multiphysics™

meshintegrate
Purpose
meshintegrate
Integrate over arbitrary cross-section.
Syntax
Description
I = meshintegrate(p,t,d)
I = meshintegrate(p,d)
I = meshintegrate(p)
I = meshintegrate(p,t,d) computes the integral I over the mesh given by p and
t, with values (for each point) in d. d is of size 1-by-np, where np is the number of
points in p (=size(p,2)). The elements are considered to be linear.
Examples Line integral in 2D:
I = meshintegrate(p,d) assumes t=[1,2,3,... (np-1) ; 2,3,4,... np],
(where np=size(p,2)), i.e., that the mesh is a line and that the points in p are
sorted.
I = meshintegrate(p) calls meshintegrate(p(1,:), p(2,:)).
This function is useful for computing integrals along cross-sections plotted with
postcrossplot, in which case p, t and d are extracted from the output when the
property outtype is set to postdata.
% Just set up a problem:
clear fem
fem.geom = circ2+rect2;
fem.mesh = meshinit(fem);
fem.shape = 2; fem.equ.c = 1; fem.equ.f = 1; fem.bnd.h = 1;
fem.xmesh = meshextend(fem);
fem.sol = femstatic(fem);
% Make a cross-section plot, with output being a postdata
% structure
pd = postcrossplot(fem,1,[0 1;0 1],'lindata','u',...
'npoints',100,'outtype','postdata');
% Call meshintegrate:
I = meshintegrate(pd.p);
Line integral in 3D:
% Just set up a problem:
clear fem, fem.geom = block3;
fem.mesh = meshinit(fem,'hmax',0.15);
fem.shape = 2;
fem.equ.c = 1; fem.equ.f = 1;
fem.bnd.h = {1 1 0 0 1 1};
fem.xmesh = meshextend(fem);
fem.sol = femstatic(fem);
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