Meaning of uu, vv after fespace is defined

Hello everyone.

Look probably this question was already asked before, (I am pretty sure it was),

But I’ve been following the tutorials, however I have a question in the theory of elasticity.

The fespace is defined then the variables u and v are defined as well. However, there are also uu, and vv variables.

What are those (uu, vv)? What are the purpose of them?.

In a 3d case what are the variables? What are the meaning of them?.

Sorry for the silly question, I think this was already asked before, but I could not find the answer.

Thanks in advance

Hi Alberto,

The uu and vv from the tutorial are there in order to define the bilinear form needed for the weak formulation of the problem. For an introduction see : Weak formulation - Wikipedia. The (u,v) from your question is the “u” from the General Concept section, while the (uu,vv) from your question is the “v” from the General Concept section.

In the 3D case you can call the 3 unknown components of the displacement vector (u,v,w) and of course you can call them (Alex1, Alex2, Alex3) since it is just a name… In addition, you need also a vector test function that you can call (uu,vv,ww), or any other name like (u1,v1,w1).

Best regards, Alex

thank you very much now i am understood