提取总体刚度阵出现的问题

NoEureka

在Comsol 4.2 with matlab运行下面这段代码。该问题是来自帮助文档中的稳态热传导问题。我想提取总体刚度阵。1*1的矩形我划的网格是2*2的，按理说应该有9个自由度。但是得到的总刚size(MA.K)的结果却是25*25。请高人指点下，谢谢了。

1. %% Create a new model object
   
2. model = ModelUtil.create('Model');
   
3. %% Create a square geometry
   
4. geom1 = model.geom.create('geom1', 2);
   
5. geom1.feature.create('sq1', 'Square');
   
6. geom1.run;
   
7. mphgeom(model,'geom1',...
   
8.     'vertexlabels','off',...
   
9.     'facelabels','on',...
   
10.     'facemode','on',...
    
11.     'facelabelscolor','r');
    
12. %% Setup material properties
    
13. mat1 = model.material.create('mat1');
    
14. def = mat1.materialModel('def');
    
15. def.set('thermalconductivity',{'4e2'});
    
16. def.set('density',{'0'});
    
17. def.set('heatcapacity',{'0'});
    
18. %% Define the physics settings
    
19. ht = model.physics.create('ht', 'HeatTransfer', 'geom1');
    
20. hs1 = ht.feature.create('hs1','HeatSource',2);
    
21. hs1.selection.set(1);
    
22. hs1.set('Q',1,'1e5');
    
23. temp1 = ht.feature.create('temp1','TemperatureBoundary',1);
    
24. temp1.selection.set([1 2]);
    
25. %% Create a mapped mesh
    
26. mesh1 = model.mesh.create('mesh1','geom1');
    
27. dis1 = mesh1.feature.create('dis1','Distribution');
    
28. dis1.selection.set([1 2]);
    
29. dis1.set('numelem',2);
    
30. mesh1.feature.create('map1','Map');
    
31. mesh1.run;
    
32. mphmesh(model,'mesh1')%visualize the mesh
    
33. %% Solve the problem
    
34. std1 = model.study.create('std1');
    
35. std1.feature.create('stat','Stationary');
    
36. std1.run;
    
37. %% Extract results
    
38. U = mphgetu(model); %get the temperature
    
39. model.sol('sol1').feature('v1').set('scalemethod','none');
    
40. MA = mphmatrix(model,'sol1','Out',{'K','L'});
    
41. size(MA.K)

复制代码

hhp886

单元类型为二阶单元
如若是一阶线性单元 输出就是9个自由度

NoEureka

hhp886 发表于 2013-9-26 19:15
单元类型为二阶单元
如若是一阶线性单元 输出就是9个自由度

哦哦，谢谢提醒，之前不知道它默认的单元是二次的。