# Mesh refinement not working?
**URL:** https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199
**Category:** mesh
**Created:** [May 14, 2020, 10:40am UTC](https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199 "2020-05-14T10:40:00Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@mackenzie](https://fenicsproject.discourse.group/u/mackenzie)
#### Post date: [May 14, 2020, 10:40am UTC](https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199/1 "2020-05-14T10:40:00Z")
I’m using a simple 1D mesh which I refine in a specific zone using the recommended marking and refine method:
size = 4e-3
nb\_cells\_init = 4000
mesh = IntervalMesh(nb\_cells\_init,0, size)
Adding at least 100 cells in the first 50e-8m:
```
nb_cells = 100
distance = 50e-8
while count < nb_cells and nb_cells > 0:
count = 0
cell_markers = MeshFunction("bool", mesh, mesh.topology().dim())
cell_markers.set_all(False)
for cell in cells(mesh):
if cell.midpoint().x() < distance:
count = count+1
cell_markers_left[cell] = True
if count == 0:
for cell in cells(mesh):
if cell.midpoint().x() < size/nb_cells_init:
cell_markers[cell]=True
mesh = refine(mesh, cell_markers)
print("Nb of cells in the mesh:" + str(len(mesh.cells())))
```
The print allows me to check that the mesh has more cells than initially.
In postprocessing, I use a XDMF/h5 file to save my solution. This file is initialized with
```
xdmf_sol = XDMFFFile(mesh.mpi_comm(), "solution.xdmf")
```
and updated at each timestep:
```
xdmf_sol.write(solution, t)
```
However when I check the output file with Paraview, the solution is only plotted over the points of the unrefined mesh.
I printed mesh.coordinates() in order to check that there are some added points and noticed that they are put at the end of the array:
> [[0.00000000e+00]
> [1.00000000e-06]
> [2.00000000e-06]
> …
> [3.37890625e-07]
> [3.30078125e-07]
> [3.33984375e-07]]
Using mesh.order() does not change this.
In the h5 file, the mesh is refined and the solution matches the refined mesh.
What am I missing here? Is it just a Paraview issue ?
---
### Author:  [@dokken](https://fenicsproject.discourse.group/u/dokken)
#### Post date: [May 14, 2020, 10:59am UTC](https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199/2 "2020-05-14T10:59:45Z")
You need to supply a minimal working example for anyone to help you with this particular issue.
---
### Author:  [@mackenzie](https://fenicsproject.discourse.group/u/mackenzie)
#### Post date: [May 14, 2020, 12:23pm UTC](https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199/3 "2020-05-14T12:23:55Z")
My apologies, I edited my question
---
### Author:  [@dokken](https://fenicsproject.discourse.group/u/dokken)
#### Post date: [May 14, 2020, 4:08pm UTC](https://fenicsproject.discourse.group/t/mesh-refinement-not-working/3199/4 "2020-05-14T16:08:57Z")
You need to make your example reproducable. As you have ignored defining several variables, I cannot run your code.
I have created a proper minimal working example to illustrate how this should work:
```auto
from dolfin import *
size = 0.1
nb_cells_init = 10
mesh = IntervalMesh(10,0, 0.1)
x = SpatialCoordinate(mesh)
V = FunctionSpace(mesh, "CG", 1)
u = project(x[0], V)
xdmf_sol = XDMFFile("solution_pre.xdmf")
xdmf_sol.write(u, 0)
print("Nb of cells in the mesh:" + str(len(mesh.cells())))
cell_markers = MeshFunction("bool", mesh, mesh.topology().dim())
cell_markers.set_all(False)
for cell in cells(mesh):
if cell.midpoint().x() < 0.05:
cell_markers[cell] = True
mesh = refine(mesh, cell_markers)
print("Nb of cells in the mesh:" + str(len(mesh.cells())))
x = SpatialCoordinate(mesh)
V = FunctionSpace(mesh, "CG", 1)
u = project(x[0], V)
xdmf_sol = XDMFFile("solution_post.xdmf")
xdmf_sol.write(u, 0)
```
This produces two paraview files, and I have attached an image of the points where the solution is saved (refined left, unrefined right).
