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Imposing perfect slip boundary conditions in Stokes equations with Nitsche's method

I am working with a 2d mesh, given by a square with a circular hole placed in the middle. Let me call $\partial \Omega$ the boundary at the circle. I have a PDE for a vector field $\vec{v}$, and I ...
James's user avatar
  • 343
1 vote
0 answers
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Formulation of multipoint constraints using Lagrange multipliers for a time dependent problem (with the Finite Element Method)

Intro Suppose we have the following static linear equations (e.g. of an elastostatic problem): $$\mathbf{K}\boldsymbol{u}=\boldsymbol{f}$$ We want a multipoint constraint of the type $$\boldsymbol{\...
Breno's user avatar
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4 votes
1 answer
210 views

Is Stokes equation a saddle point problem or a minimum problem?

Consider $\Omega \subset \mathbb{R}^2 $ (or $\mathbb{R}^3$). The well known stationary Stokes equations in the incompressible case are \begin{equation} \begin{cases} - \Delta u + \nabla p = f \text{ ...
tommy1996q's user avatar
4 votes
1 answer
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Difference between variation and differential

Been trying to understand how the numerical formulation for structural elements used in FEM are derived. Came across this piece from "Fundamentals of FEM for Heat and Fluid Flow" by Roland ...
Fady Megally's user avatar
1 vote
1 answer
207 views

How to solve Poissons equation using FEM with integral BC?

I have a 3-dimensional domain D, with 3 types of BC which I am trying to solve the Poisson equation on. $$-\nabla \cdot (\sigma(x,y,z)\nabla u)=0$$ Insulator (Neumann BC) Electrode set at some ...
Pelle's user avatar
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1 vote
1 answer
441 views

Generalized Lax-Milgram for Weak Formulation of 1D Linear Schrodinger

I am interested in the variational formulation of the 1D Schrodinger equation: $i u_t- \beta u_{xx} = 0 $ and $u(x,0)=u_0(x)$ which upon integration by parts yields: $i(u_t,v) + \beta (u_x,v_x) = 0$ ...
Sriram Nagaraj's user avatar