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March 8, 2010 3:35pm UTC in response to Julien LAUNAY

Re: export current plot/particle tracing with comsol w/ matlab

I finally found the solution of my problem, maybe it could be useful for somebody.

Some codes seems to work with Comsol but not with Matlab. This is the one I use :

"VAR_PART=postplot(fem, ...
'outtype','postdataonly', ...
'partmasstype','massless', ...
'partstart',{[0.001],[eps]}, ...
'partcolordata','partt', ...
'partdata',{'u','v'}, ...
'partedgetol',0.001, ...
'parttvar','partt', ...
'partres',5, ...
'solnum','end', ...
'geom','off', ...
'axis',[-0.038658065092179075,0.08865806583723716,-0.005000000074505795,0.10500000156462193]);"

And the datas are contained in the workspace of Matlab, in VAR_PART, to access them, by example the time :
VAR_PART{1,1}.parttime

To plot the results, just change outtype in "postdata" or "handle".

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March 9, 2010 10:43am UTC in response to Jacopo Biasetti

Re: export current plot/particle tracing with comsol w/ matlab

Hi,

I'm not sure for your code, but using the one I post below, it seems to work, with something like that :

A = {0.24, -0.015};
figure
h=postplot(fem, ...
'outtype','postdata', ...
'partstart',A, ...
'parttstar','auto', ...
'partdata',{'u','v'}, ...
'parttvar','partt', ...
'geom','off');
grid on
xlabel('x-coordinate');
ylabel('y-coordinate');


You can change 'geom' in 'on' to see your geometry with the particle.
I think the problem was the line 'partdata'

Hope it will help you,
JL

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March 9, 2010 5:14pm UTC in response to Jacopo Biasetti

Re: export current plot/particle tracing with comsol w/ matlab

Forgot this...and doesn't work anyway!

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November 17, 2010 9:12am UTC in response to ??fatemeh sharifi

Re: export current plot/particle tracing with comsol w/ matlab

Hi

I'm not sure I've understood your question but, the x and y you're talking about are the positions of your mesh elements. All informations about your mesh can be accessed with the simple command:

fem.mesh

During a particle tracing, comsol calculate the succesives positions of a particle at each time in fonction of the velocity. All positions are independent of your previous Comsol mesh. And through the command you use, you can only deal with mesh elements.



For your other question, to plot new variables, you need to create your own mesh in matlab with the command meshgrid and griddata.
You can find help on matlab forums, or directly in matlab typing "help griddata"



Hope I've correctly answered your questions,
JL

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November 17, 2010 4:28pm UTC in response to ??fatemeh sharifi

Re: export current plot/particle tracing with comsol w/ matlab

Hi Fatemeh

I have complicated geometries too, sometimes in 2D or 3D. I don't know if there are functions in Matlab to use your comsol mesh, directly.

I use to make a new grid, larger than the entire geometry in comsol, in 2D or 3D, with the command meshgrid, and griddata enables to interpolate the values from comsol in the right place in my matlab mesh.

I just need to impose in my matlab's mesh, NaN on the cells located outside my geometry, in order to have the perfect representation of it. I assume that it does represent really complicated programs but I did'nt find other ways.

But you're right, maybe there's a possibility of using the fem.mesh. Did you try to get X and Y positions of the different elements :

AA=get(fem.mesh,'p');
Xpos=AA(1,:);
Ypos=AA(2,:);

MESH=[Xpos' Ypos'];

for i=1:length(MYMESH)
MYMESH(:,3)=0;
end

X1=MYMESH(:,1);
Y1=MYMESH(:,2);
Z1=MYMESH(:,3);

plot3(Z1,X1,Y1);

I just typed that, never test it before but these commands seems to work with my programs... Maybe a start ?

Best regards,
JL

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November 19, 2010 1:19pm UTC in response to ??fatemeh sharifi

Re: export current plot/particle tracing with comsol w/ matlab

Hi Fatemeh

The rule to apply your datas on a new mesh is to create a new matlab mesh which must be regular. I mean that you have to create a rectangular mesh by the commands below :

with a vector X and a vector Y (coordinates of your particle track for example)

xi=linspace(min(X),max(X),100);
yi=linspace(min(Y),max(Y),100);

[XI,YI]=meshgrid(xi,yi);

These commands create a rectangular mesh of hundred coordinates in Y and X. Now, to apply your datas "DAT", depending of Xcoord and Ycoord, you can use the next command :

DAT_2=griddata(XI,YI,DAT,X,Y);


I repeat myself, but the only possibility I've found for complicated geometries is to create a surface larger that my comsol domain, (from min(X) to max(X) and from min(Y) to max(Y)) and just apply NaN on the cells outside of my comsol domain.

You can also create matrices before you use them as :
DAT_2=NaN(100,100);

That's just an example. You have to modify it for your own case.

Finally to see the result :
surf(DAT_2);
shading interp



Julien

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