# Re: [deal.II] Interpolating values of the neighbor cells in DG

```Dear Prof. Bangerth,

I will have to use arbitrary meshes, because I have solid particles moving
in the mesh and```
```
have to refine the mesh adaptively. Later, I will need to move the mesh and
even regenerate

the mesh if the cells are too distorted.

Best,
Jiaqi

2016-09-19 23:26 GMT-04:00 Wolfgang Bangerth <bange...@colostate.edu>:

>
> Jiaqi,
>
> Yes, I want to extend the solution from the neighboring cells to the
>> current
>> cell. I know different cells have different polynomial descriptions,
>> but in order to apply the limiters, information from the neighbor cells is
>> required. Is it possible to extend the solutions from neighbors through
>> interpolation? I am not sure how to do that in deal.II.
>>
>
> This is one of those operations that are easy to write down in formulas
> and difficult to implement.
>
> Are you using arbitrary meshes, or rectangular ones? I ask because what
> you really want to do is evaluate the solution on one cell at points
> *outside this cell*. That's possible, but you will need to know the
> reference coordinates of a point on a neighboring cell in the coordinate
> system of the current cell. This is simple if you are on a rectangular
> mesh, but not so simple in the general case.
>
> Best
>  W.
>
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth          email:                 bange...@colostate.edu
>                            www: http://www.math.colostate.edu/~bangerth/
>
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--
Jiaqi Zhang
Department of Mathematics
Virginia Tech

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