# Tag Info

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### Under what circumstances is parallel scaling of the finite element method not "solved"?

There are multiple questions in the post, so let me address these separately: Scaling: Every parallel program is composed of sequential and parallel tasks, and Amdahl's law then guarantees that there ...
Accepted

### FEM for vector valued problems: reference request

Short answer: Just replicate the vector of interpolation functions into a block-diagonal matrix, as showed e.g. on page 5 in this lecture note. Detailed answer: Mathematically oriented texts typically ...

### Comparing various implementations/software packages for large-scale finite element simulations

As one of the library's authors, I would of course love for deal.II to come out on top with this comparison. But I suspect it may not, and the answer lies in a factor you omit from your comparison: ...

### Spectral Element vs Finite Element

The SEM is a FEM! It's almost like all these different names are designed to confuse the newcomer. I will speak primarily about the most popular form which uses a tensor product Lagrange basis with ...
Accepted

### Spectral Element vs Finite Element

The main advantage is that it reduces the Runge phenomenon and leads to faster convergence rates. It also presents less numerical dispersion and need less nodes per wavelength (see 1 and 2). So, I ...

1 vote

### deal.ii - ParaView "warp by scalar" of my output is not continuous

It seems like you are using deal-ii for your simulations. Its a well established fem solver and there is a very less chance that the mistake is with the FEM solver. However, Please check the BC that ...
1 vote
Accepted

### Displacement field not correct?

As mentioned by @Wolfgang Bangerth , the value may be at the interior points. However, to visualise that better in paraview, You can use a filter called "plot over line" which plots the data ...
1 vote

Its not the summation that is wrong, but the lack of indices inside it. Below this expression on their site they define: $$\epsilon(\mathbf{u})=\frac{1}{2}([\nabla\mathbf{u}]+[\nabla\mathbf{u}]^{\... 1 vote Accepted ### Manufactured solution for -\operatorname{div}(a(x) \nabla{u}) = f when \alpha(x) is discontinuous @cfdlab's answer gives a general way to construct solutions for discontinuous coefficients, but here is a slightly more theoretical perspective to it as well. All of this can be understood in 1d, so ... 1 vote ### Manufactured solution for -\operatorname{div}(a(x) \nabla{u}) = f when \alpha(x) is discontinuous If you want to use the coefficient of the form$$ \alpha = \begin{cases} \alpha_1 & r < 0.5 \\ \alpha_2 & r > 0.5 \end{cases} $$it is useful to work in polar coordinates. You build two ... 1 vote ### Developing a C++ solid mechanics program This is not really a program as much as a big repository of codes. John Burkardt from Florida State University maintains a rich collection of scripts in C++, Matlab and Fortran for a large range of ... 1 vote ### Boundary elements method -- calculation of solid angle If a homogeneous Neumann problem is considered, i.e. f=0 in \Omega and \mathbf{n}\cdot\nabla\phi on \Gamma, one solution is given by the constant function$$ \phi\left(\mathbf{x}\right)=\...

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