lots of thanks for your response, First of all, I should say that my model is 2D and circular (attachment). I also checked mentioned matlab library and it does not include circular object.
Besides, I tried to import some example of library into comsol, but it shows this message:"The imported file did not contain any geometry"
and I think that the library does not work for my model.
I also tried to export my geometry as .il (illustrator format) then export it as .dxf but I saw the same message. Matlab can not generate a .dxf file.