[Gmsh] Forcing only the geometry points to be part of the mesh

[Parvez Ahmed]

Hello everyone,

I am using Gmsh for the purpose of 2D free meshing with only quad elements.

For the geometry, I have a circle (which has been halved to a semicircle to
reduce the computing time) which is at the centre of a bigger square and
first of all, the outer square is meshed using structured meshing
technique. Then, the coordinates of the inner circle are obtained and this
circle needs to be freely meshed. To ensure continuity, only the geomtery
points of the circles (i.e. the points used to generate the circle) need to
be part of the mesh and there should not be any other mesh points in the
middle of two geometry points.

2D meshing algorithm being used is either 'Delaunay for Quad', 'Frontal'
and 'Delaunay'.

Intially it works well when the element sizes are big, but after splitting
a couple of times to adjust with the geometry points, Gmsh inserts mesh
points(nodes) in the middle and also triangular elements.

I have used 'Point In Surface' and 'Line In Surface' till now but not
getting the desired results.

Can anyone kindly tell me how to go about this?

Please find attached the .geo file and also a couple of screenshots to
illustrate what I am trying to do.

Thanks a lot in advance and have a good day everone.
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