function [UserVar,EleSizeDesired,ElementsToBeRefined,ElementsToBeCoarsened]=DefineDesiredEleSize(UserVar,CtrlVar,MUA,F,x,y,EleSizeDesired,ElementsToBeRefined,NodalErrorIndicators)

Define desired sizes of elements or specify which elements to refine or coarsen.

[UserVar,EleSizeDesired,ElementsToBeRefined,ElementsToBeCoarsened]=...
         DefineDesiredEleSize(UserVar,CtrlVar,MUA,x,y,EleSizeDesired,ElementsToBeRefined,ElementsToBeCoarsened,s,b,S,B,rho,rhow,ub,vb,ud,vd,GF,NodalErrorIndicators)

Only used in combination with adaptive meshing.

You need to set

CtrlVar.AdaptMesh=1;

in Ua2D_InitialUserinput for this m-file to be called.

Allows user to set:

On input EleSize are desired element sizes at (x,y) as calculated by Úa based on some user-defined criteria.

On output EleSize are user-modified values.

Do not modify the size of the (nodal) vector `EleSizeDesired' or the logical (element) vector 'ElementsToBeRefine', only the values.

When using the global remeshing option x,y are the locations where new element sizes are specified (these are the coordinates of the mesh)

Note: When using the local remeshing option, x and y as given on input are not relevant. In this case use MUA.xEle and MUA.yEle as the x, y locations where the elements are to be refined or coarsened.

ElementsToBeRefined can either be a logical array in which case values set to true/1 indicate elements to be refined, or a list of numbers of elements to be refined.

Note that this m-file is only called if the adaptive meshing option is used. Also, that elements will only be refined/coarsened if local mesh refinement is used. These options must be set accordingly in Ua2D_InitialUserInput.

Example: To set desired ele size to 1000 within a given boundary (this boundary must of course be within the overall boundary of the computational domain):

Boundary=[0        0 ; ...
        10e3      0 ; ...
        10e3      10e3;
        0       10e3];

I=inpoly([x y],Boundary) ;
EleSizeDesired(I)=1000;

Here Boundary does not have to be just a simple square, it can be a polygon of any shape.

Example: To set all ele size of all floating elements (i.e. ice shelves) to 1000:

EleSizeDesired(GF.Node<0.5)=1000;

Example defining either EleSizeDesired or ElementsToBeRefined depending on adaptive meshing option selected:

   switch lower(CtrlVar.MeshRefinementMethod)

       case 'explicit:global'

       % when using global mesh refinement, return EleSizeIndicator defined at nodes

           EleSizeIndicator=EleSizeDesired;

           EleSizeIndicator(GF.node<0.1)=UserVar.MeshSizeIceShelves;
           EleSizeDesired=min(EleSizeDesired,EleSizeIndicator);

           EleSizeIndicator(s<1500)=CtrlVar.MeshSizeMax/5;
           EleSizeDesired=min(EleSizeDesired,EleSizeIndicator);

           xmin=-1727e3   ; xmax=-1100e3 ; ymin=-600e3 ; ymax=-20.e3;
           ind=x< xmax & x>xmin & y>ymin & y< ymax ;
           EleSizeDesired(~ind)=CtrlVar.MeshSizeMax;

       case 'explicit:local:newest vertex bisection'

       % When using local mesh refinement, return ElementsToBeRefined and ElementsToBeCoarsened defined over elements
       %
       % ElementsToBeCoarsened is only used in combination with the 'newest vertex bisection' local mesh-refinement method
       %
           xmin=-1727e3   ; xmax=-1100e3 ; ymin=-600e3 ; ymax=-20.e3;
           ind=MUA.xEle < xmax & MUA.xEle > xmin & MUA.yEle >ymin & MUA.yEle < ymax ;

           ElementsToBeRefined(~ind)=false;

   end

ElementsToBeCoarsened=[];  % Always need to define this as it is a required output.

Temp=EleSizeDesired;
x=MUA.coordinates(:,1) ; y=MUA.coordinates(:,2) ;

D=10e3; I=x>-D & x< D & y> -D & y < D ; Temp(I)=0.5e3;
D=1e3;  I=y> (UserVar.Crack.b-D) & y < (UserVar.Crack.b+D)  & x> -D & x < D ; Temp(I)=0.1e3;
D=0.1e3;  I=y> (UserVar.Crack.b-D) & y < (UserVar.Crack.b+D)  & x> -D & x < D ; Temp(I)=0.01e3;
D=0.01e3;  I=y> (UserVar.Crack.b-D) & y < (UserVar.Crack.b+D)  & x> -D & x < D ; Temp(I)=0.001e3;

EleSizeDesired=min(Temp(:),EleSizeDesired(:));

end

Published with MATLAB® R2024a