Hello, I am recently new to using fenics. I would like to solve the stationary Navier-Stokes equations. I have found some posts from the legacy fenics, but it seems that in the new fenics it is not as straight-forward. My starting point is a working example of the Stokes equation with an inlet and…

please use the search button, there were posts about stationary NS equations in dolfinx in the last month or so, to which I (and others) replied.

I spent some time searching through the forum, but the only similar topic I could find is Convergence problem solving steady Navier-Stokes with multiphenicsx but even there the multiphenicsx library is used, so i was hoping somebody could provide some minimalistic example, just to get the basic idea…

[image] Newton iteration against time-stepping for steady solution of the incompressible Navier-Stokes equations General Hi! I’m interested in using FEniCSx to compute the steady solution of incompressible Navier-Stokes equations. I’ve found several examples (in the tutor…

[image] marhatom: a_uu = ufl.inner(ufl.grad(u), ufl.grad(v)) * ufl.dx + ufl.dot(ufl.dot(u, ufl.grad(u)), v)*ufl.dx Please note that you need to replace you trial function definition by a function definition in the case of a non-linear problem [image] marhatom: u, p = ufl.TrialFunction(V)…

Thank you guys for help, but I was thinking something more like this u_old = fem.Function(V) u, p = ufl.TrialFunction(V), ufl.TrialFunction(Q) v, q = ufl.TestFunction(V), ufl.TestFunction(Q) a_uu = ufl.inner(ufl.grad(u), ufl.grad(v)) * ufl.dx + ufl.dot(ufl.dot(u_old, ufl.grad(u)), v)*ufl.dx a_up …

[image] marhatom: for i in range(niter): A = fem.petsc.assemble_matrix_nest(a, bcs=bc) A.assemble() b = fem.petsc.assemble_vector_nest(L) fem.petsc.apply_lifting_nest(b, a, bcs=bc) for b_sub in b.getNestSubVecs(): b_sub.ghostUpdate(ad…

I am sorry, but I dont think I follow, how can I assemble the matrix in the loop, when I zero out all entries.

See for instance the loop in: Test problem 2: Flow past a cylinder (DFG 2D-3 benchmark) — FEniCSx tutorial

Ok, I see. So my aim is to solve dfg_benchmark1_re20 . My current code looks like this from mpi4py import MPI from petsc4py import PETSc from dolfinx import fem, io import dolfinx.fem.petsc import ufl import numpy as np msh, cell_markers, facet_markers = io.gmshio.read_from_msh("mesh/DFG.msh", M…

Hi, I referenced your code. But when the kinematic viscosity is very small (such as 1e-6), the result will not converge.

Stationary Navier-Stokes equations

General

francesco-ballarin March 24, 2024, 6:00am 4

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Stationary Navier-Stokes equations

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