Contents

Illustrate how to randomly shake internal nodes

clear variables;

Crete Mesher object

When Mesher object is created it takes care of initializing interface to GMSH mesh generator

mesher = mp.Mesher();

Create object describing geometric model to be meshed

L = 10;
geom = mp.geoms.SquareGeom('my_domain', struct('da', L));

Generate Mesh object

Ne = 5;
meshingparams.lc = L/Ne;
meshingparams.order = 2;
mesh = mesher.generate(geom, meshingparams);

Visualize mesh

viewer = mp.Viewer();

viewer.show(mesh);

Selecting nodes

selector.b_south = 0;
selector.b_north = 0;
selector.b_west = 0;
selector.b_east = 0;

nodesTag = mp_tag_region_nodes(mesh, selector, 'min', 1);
boundaryNodes = find(nodesTag==0);
internalNodes = find(nodesTag==1);

boundaryPts = mesh.nodes(boundaryNodes, :);

viewer.showPoints(boundaryPts);

radius = L*ones(mesh.countNodes(), 1);

Iterate over elements and calculate maximum allowabel radius

for i=1:mesh.countElems()
  nodes = mesh.elemNodes(i);
  nen = length(nodes);
  pairs = combnk(1:nen, 2);
  for p = pairs'
    n = nodes(p);
    nodesDist = norm(diff(mesh.nodes(n,:), 1));
    radius(n) = min(radius(n), nodesDist*[1;1]);
  end
end

radius = 0.3*radius;

direction = 2*pi*rand(mesh.countNodes(), 1)
distance = radius.*(0.5+0.5*rand(mesh.countNodes(),1));
u = distance.*[cos(direction), sin(direction)];

hold on

for i=1:mesh.countNodes
  if nodesTag(i)
    xy = mesh.nodes(i, 1:2);
    r = radius(i);
    circle = [xy(1)-r, xy(2)-r, 2*r, 2*r];
    rectangle('Position', circle, 'Curvature', [1,1]);
    xy(end+1,:) = [xy + u(i, :)];
    line(xy(:,1), xy(:,2), 'Color', 'red');
  end
end

mesh.nodes(internalNodes, 1:2) = mesh.nodes(internalNodes, 1:2)+ u(internalNodes, :);

viewer.stackFigure();

viewer.show(mesh);

viewer.plot_curved_elements(mesh, 70);
% Report demo status
mp_manage_demos('report', 'shake_internal_nodes', true);

direction =

    5.4734
    2.2040
    4.3073
    1.8482
    3.3340
    5.2303
    3.7541
    2.1068
    1.8801
    2.8437
    2.6556
    2.2595
    3.5080
    4.6656
    2.6662
    2.6977
    0.7846
    0.1535
    1.8233
    1.9950
    4.1073
    6.0126
    5.8794
    2.8770
    1.5110
    4.7997
    4.7710
    4.6536
    4.6727
    0.6655
    4.2824
    2.9108
    1.3331
    0.6190
    5.1747
    1.0996
    1.0277
    4.1845
    5.6196
    3.2456
    4.4152
    0.9650
    5.9907
    3.3985
    4.2709
    0.2297
    5.0844
    4.7037
    0.7552
    3.2990
    2.0473
    3.4334
    2.5062
    2.6081
    1.1356
    1.6046
    0.1290
    5.8036
    4.1073
    5.8598
    1.0274
    5.7874
    4.9930
    3.6279
    2.7648
    1.6186
    4.7246
    1.4368
    0.4033
    4.8213
    4.2173
    4.4938
    4.0342
    2.6330
    2.4552
    5.1280
    1.9945
    5.1179
    4.9579
    5.3549
    3.1770
    3.9940
    5.9746
    2.7895
    0.3771
    5.4460
    3.9659
    2.2310
    6.2644
    1.4085
    4.0995
    3.8013
    2.4331
    0.8934
    0.1579
    2.6459
    1.1567
    4.5602
    2.3271
    5.2877
    4.6133
    3.5879
    1.1112
    6.0154
    1.6671
    5.8093
    1.4060
    2.3472
    0.5498
    4.0220
    1.1348
    0.2831
    4.5438
    2.1830
    4.1508
    2.4119
    3.9417
    0.1360
    5.7213
    5.0301
    4.6863
    5.1089
    2.4084
    3.8785
    3.6159
    3.3304
    1.7283
    1.5622
    2.8377
    1.4308
    5.0545
    6.1959
    0.1884
    3.3657
    0.5471
    5.0397
    6.2150
    0.4206
    5.9024
    0.1142
    4.2967
    4.9244
    3.3561
    5.5629
    5.6486
    3.9329
    0.8663
    1.3685
    1.1444
    0.2628
    0.6719
    3.8732
    5.9041
    2.2271
    2.5801
    6.1848
    5.9412

Published with MATLAB® R2017a