[Gmsh] 3 levels of mesh refinement in a box

[Eric Nutsch]

If I am understanding you correctly why not just change:
Field[3].LcMax = lc; to Field[3].LcMax = lc/ 2;

or maybe change:
Field[3].DistMax = 1; to Field[3].DistMax = 5;

Just some ideas

Eric



On Wed, May 26, 2010 at 2:48 PM, Olavo Luppi Silva
<olavo.luppi at ig.com.br> wrote:
> Dear gmsh community,
>
> I'm trying to make a 3D mesh of a box with 3 levels of mesh refinement.
> Level 1, the mesh is coarse (lc), and should be used at the inner portion of
> the box
> Level 2, the mesh is intermediate (lc/8), and should be used near the faces
> of the box
> Level 3, the mesh is refined (lc/40), and should be used inside the circle
> at one of the faces of the box.
>
> The file below shows the best I could get. Notice that at the top face,
> element size is smaller (lc/8) near the vertices, and bigger (lc) at
> interior, which is ok. At the front face, there are big elements (lc) near
> tiny elements (lc/40) inside the circle. I'd like them to be medium size
> (lc/8).
> I tried to use
>   Field[2] = Attractor;
>   Field[2].FacesList = {1,2,4,5,6,27};
>
> instead of
>    Field[2] = Attractor;
>    Field[2].EdgesList = {1:12};
>
> But gmsh generated a bunch of errors. Any suggestions?
>
> Olavo Luppi
>
> =======================
>
> lc = 1.0;
> L = 4;
> W = 3;
> h = 2.0;
> R = 0.1;
>
> Point(1) = {0.0,0.0,0.0,lc};
> Point(2) = {L,0.0, 0.0,lc};
> Point(3) = {L,W,0.0,lc};
> Point(4) = {0,W,0.0,lc};
>
> Point(5) = {0.0,0.0,h,lc};
> Point(6) = {L,0.0,h,lc};
> Point(7) = {L,W,h,lc};
> Point(8) = {0,W,h,lc};
>
> Line(1) = {4,3};
> Line(2) = {3,2};
> Line(3) = {2,1};
> Line(4) = {1,4};
>
> Line(5) = {5,6};
> Line(6) = {6,7};
> Line(7) = {7,8};
> Line(8) = {8,5};
>
> Line(9) = {1,5};
> Line(10) = {6,2};
> Line(11) = {7,3};
> Line(12) = {8,4};
>
> a[] = Point{1};
> b[] = Point{2};
> c[] = Point{6};
> d[] = Point{5};
>
>
> Point(20) = {(a[0]+b[0]+c[0]+d[0])/4,(a[1]+b[1]+c[1]+d[1])/4,
> (a[2]+b[2]+c[2]+d[2])/4, lc};
> centro[] = Point{20};
>
> Point(21) = {centro[0]+R, centro[1], centro[2],lc};
> Point(22) = {centro[0], centro[1], centro[2]+R,lc};
> Point(23) = {centro[0]-R, centro[1], centro[2],lc};
> Point(24) = {centro[0], centro[1], centro[2]-R,lc};
>
>
> Line Loop(1) = {2,3,4,1};
> Line Loop(2) = {5,6,7,8};
> Line Loop(3) = {9,5,10,3};
> Line Loop(4) = {10, -2, -11, -6};
> Line Loop(5) = {1, -11, 7, 12};
> Line Loop(6) = {12, -4, 9, -8};
>
>
> Plane Surface(1) = {1};
> Plane Surface(2) = {2};
> //Plane Surface(3) = {3};
> Plane Surface(4) = {4};
> Plane Surface(5) = {5};
> Plane Surface(6) = {6};
>
>
>
> Circle(21) = {21, 20, 22};
> Circle(22) = {22, 20, 23};
> Circle(23) = {23, 20, 24};
> Circle(24) = {24, 20, 21};
>
> Line Loop(25) = {21, 22, 23, 24};
> Plane Surface(26) = {25};
> Plane Surface(27) = {3, 25};
>
>
> Surface Loop(28) = {2, 27, 6, 5, 1, 4, 26};
> Volume(29) = {28};
>
> Field[1] = Attractor;
> Field[1].NodesList = {20};
>
>
> Field[2] = Attractor;
> Field[2].EdgesList = {1:12};
>
> Field[3] = Threshold;
> Field[3].IField = 1;
> Field[3].LcMin = lc / 40;
> Field[3].LcMax = lc;
> Field[3].DistMin = R;
> Field[3].DistMax = 1;
>
> Field[4] = Threshold;
> Field[4].IField = 2;
> Field[4].LcMin = lc / 8;
> Field[4].LcMax = lc;
> Field[4].DistMin = 0.3;
> Field[4].DistMax = 1.5;
>
> // Use minimum of all the fields as the background field
> Field[5] = Min;
> Field[5].FieldsList = {3,4};
> Background Field = 5;
>
>
> // Don't extend the elements sizes from the boundary inside the domain
> Mesh.CharacteristicLengthExtendFromBoundary = 0;
>
>
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>
>



-- 
Eric Nutsch
Mechanical Engineer, BSME, EIT
bote Innovations LLC
1574 Coburg Road #145
Eugene, OR 97401-4802

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