Hello, I am trying to figure out a way to calculate the (approximated) area of a 2D field that meets certain criteria, for example, area in the field that has field value greater than zero. I was thinking that solving the problem with constant elements, and if that value in that element is greater…

The R space is a constant single constant for the whole mesh, not per element. A per element function space is the DG, 0 space: from dolfin import * mesh = UnitSquareMesh(100, 100) R = 0.2 V = FunctionSpace(mesh, 'Lagrange', 1) u0 = Expression('(pow(x[0]-0.5,2) + pow(x[1]-0.5,2) > pow(R,2)) ? m : …

Hello Dokken Thanks for correcting my misunderstanding of the R space! I like your approach to calculate the area! However, this approach only works with this particular test case where the field of interest is a binary field. If the parameter n is changed to 2.0 in u0, or m is changed to -1.0, …

Please provide a minimal example of such a field, as I do not understand what you want to do. The resulting DG 0 function is a binary function, that is one or zero on each element (or 2 and -1 if you change m and n).

One example of such field would be: R=0.2 u0 = Expression('(pow(x[0]-0.5,2) + pow(x[1]-0.5,2) > pow(R,2)) ? m*x[0] : n*x[0]', degree=2,R=R,m=-1.5,n=2.0) u = interpolate(u0, V) I just tried something with Conditional(), it works to convert the field to binary, but the calculation a…

I just did another test using Conditional() on the DG,0 space, the accuracy seems to improve a lot, but I ran into plotting issue: Object cannot be plotted directly, projecting to piecewise linears. Traceback (most recent call last): File "foo.py", line 56, in <module> h = plot(u_DG, mode='co…

You can visualize DG in paraview using XDMFFile.write_checkpoint: [image] Load DG0 Function from parallelly saved XDMF file I would not plot with matplotlib in parallel. Usually, one should look at output from parallel computations in Paraview, for instance by adding: x…

Approximate area in a 2D field

dokken September 17, 2020, 12:23pm 7

You can visualize DG in paraview using XDMFFile.write_checkpoint:

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Approximate area in a 2D field

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