sed as constraints for the coarse dual grid</span>
            coarseGrid = cell(1,1);
            coarseGrid{1} = fset{3};
            coarseGrid{1}.merge = true;
            coarseGrid{1}.apertureType = <span class="string">'constants'</span>;
            fineGrid = cell(2,1);
            fineGrid{1} = fset{1};
            fineGrid{2} = fset{2};
    <span class="keyword">end</span>


    t = tic;

    <span class="comment">% filename for to save the grids</span>
    grid_filename = [<span class="string">'