Questions tagged [fenics]
Questions about the finite element method software FEniCS and its subpackages (Dolfin, UFL, FFC).
24
questions with no upvoted or accepted answers
9
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0
answers
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Simple turbulence model appropriate for buoyancy-driven cavity like problem
Which turbulence model is suitable for resolving incompressible buoyancy-driven flow of a fluid within an cylindrical ampoule?
I prefer turbulence model which is sufficiently simple so that fully ...
- 917
6
votes
0
answers
687
views
Stochastic Galerkin projection approach for using generalized polynomial chaos expansion (GPCE) in solving PDE
I want to know if there is any way to define the test and trial function in the way that I want instead of using the default functions. So if I want define the polynomial and basis and coefficient, ...
- 111
5
votes
0
answers
1k
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Poisson equation with pure Neumann boundary conditions (using FEM)
I am trying to derive the correct variational form for the Poisson equation with pure Neumann boundary conditions, and an additional contraint $\int_{\Omega} u \, {\rm d} x = 0$, as described in this ...
- 51
4
votes
0
answers
539
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Fenics: Result of Steady state dynamic linear elastic doesn't match with actual values
I solved the steady state dynamic linear elastic model in a solid. My equation is a function of frequency and the strong form is:
$$\operatorname{div}(\operatorname{stress}(\vec x, w)) + w^2 \rho u( \...
- 111
3
votes
0
answers
155
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Petrov-Galerkin enrichment method for Darcy equation
I was reading about Petrov-Galerkin Enrichment Method for Darcy equations. Here are a couple papers that discuss this in detail:
A Petrov–Galerkin enriched method: A mass conservative finite element ...
- 781
3
votes
0
answers
426
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A Question About Weak Forms in Fenics
Is it possible to use test and trial functions from two different function spaces (defined over two different meshes) in a single weak form? Under what conditions can I do this (eg., each term in the ...
- 181
2
votes
0
answers
372
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Stationary 2D/3D Navier-Stokes source code
Trying to solve stationary Navier-Stokes problem for incompressible laminar Newtonian fluid.
I've found a couple solutions for instationary Navier-Stokes equations (like FeniCS examples or CFD Python)...
- 121
1
vote
0
answers
56
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Accessing nodal and degree of freedom organisation in the solution vector in Fenics and Firedrake
Context
Let suppose a solution to a finite element problem (associated to a mesh) stored in a vector $X$ of size $(N \cdot d)$ corresponding to $N$ nodes in the mesh and $d$ degrees of freedom for ...
1
vote
0
answers
187
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Solving coupled PDEs with self-consistency condition
I am figuring out how to attack a problem (the Usadel equations of superconductivity) in which I need to solve a set of nonlinear PDEs for the fields $\{G_i (r)\}$
$$ U(G_i(r), \nabla G_i(r), \Delta(r)...
- 161
1
vote
0
answers
51
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Add orthogonality constraint to PDE over entire domain finite element
I have a nonlinear differential equation for $u:\mathbb{R}^2\rightarrow\mathbb{R}^3$ that I can express in the form:
$ \nabla (g(u)_{ij} \nabla(u)^j) = 0 $
which is similar to the "Nonlinear Poisson" ...
- 121
1
vote
0
answers
462
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Immersed boundary method in FEniCS?
I have looked at the FEniCS tutorials and documentation but I cannot find any mention to the possibility of implementing an immersed boundary method (IBM) for fluid dynamics.
In particular, I want ...
- 155
1
vote
0
answers
41
views
Setting up diffusion with integral B.C. in Fenics
I'm trying to model diffusion through a cylindrical domain $D = \{ (x,y,z) : x^2 + y^2 \leq 1, \;\; 0 \leq z \leq 1\}$.
The is an initial concentration of the diffusant at the upper flat surface, ...
- 111
1
vote
0
answers
133
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computational tool for higher order Lagrangian interpolation for finite element
In finite element, I can calculate the Lagrangian interpolation shape functions for each degree of freedom in an element, from the the number of nodal degrees of freedom and the number of nodes ...
- 53
1
vote
0
answers
385
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How to add a Ricker Wavelet (Mexican Hat) to a 2D/ 3D fem mesh?
I have a 2D square mesh and a 3D beam shaped mesh and I want to propagate a seismic wave in them. I am trying to simulate them using Open source FEM codes (fenics). I have left the top surface to be ...
- 347
1
vote
0
answers
211
views
Weak form for elastoplastic wave propagation
I am trying to simulate elastoplastic seismic wave propagation using Fenics Solid Mechanics Application.
The app. provides some quasi-static demos to show elastoplastic behaviour in a cube/ beam/ ...
- 347
0
votes
0
answers
57
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It is possible to solve integro-differential equations using in Fenics?
I am interested in solve the following integro-differential equation:
\begin{align}
\frac{\partial{\rho(\theta, t)}}{\partial{t}} = D \frac{\partial{\rho(\theta, t)}}{\partial{\theta^2}} - \beta \...
- 111
0
votes
0
answers
103
views
Dolfin convert : How to interpolate data at vertices of (3D) cells?
I hope that one of you guys can help me because i have been stuck here for a week.
I am trying to read a gmsh file (.msh) using dolfin convert to XML and then download it with dolfin.
The thing is ...
- 1
0
votes
0
answers
178
views
How to use FEniCS to calculate the electric field of an isolated charged sphere
Initially I thought that this is the kind of question which ought to have already been answered in the form of an example online, but so far I haven't found one. I will admit that I am very new to ...
- 11
0
votes
0
answers
424
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Time-dependent Schrodinger equation implementation in FEniCS
For our Bachelors thesis we're trying to solve the Schrodinger equation $i\partial_tu = -\nabla^2u+Vu$ in FEniCS. Given the domain $[-5, 5]^2$ with an initial value of $u_0(x, y)=e^{(-2(x^2+y^2))}$ ...
- 109
0
votes
0
answers
389
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Heat diffusion simulation in a 3D piston using FENICS
I'm trying to simulate the heat diffusion in a 3D piston. I marked the boundaries on GMSH.
I have used a Dirichlet BC of 300 on the top face of piston. But the results look abnormal. There is a ...
- 119
0
votes
0
answers
143
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FEniCS, refinement not 'respecting' domain boundary
Short question: how to ensure that extra points are not included as 'boundary' points after calling the refine function.
More details.
I am working with a hexahedral mesh in $3$d. Let $X$ be the set ...
- 159
0
votes
0
answers
149
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FEniCS implementation of Maxwell equations for a dipole antenna
someone knows where I can find a FEniCS implementation of Maxwell equations for a dipole or other type of antenna? I mean a dipole antenna with an arbitrary geometry of every 'leg' in the dipole.
- 111
0
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0
answers
78
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Coupling 1D-3D problem in FENICS
I was wondering whether any of you knew if FENICS has the capability to solve coupled 1D-3D problems that are linear non-iteratively? As an example, pipes embedded in a porous domain will provide ...
0
votes
0
answers
93
views
Stokes Equation fails to converge for an ellipse
This might be because of the mesh, but the following code blows up for all values of b not 1. Does anybody have any experience working with the ellipse mesh in Fenics?
...