# [Gmsh] Problem with geometry.

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 January 6, 2011, 04:56 Problem with geometry. #1 Senior Member   Andrea Ferrari Join Date: Dec 2010 Posts: 319 Rep Power: 15 Hi all, I built a simple geometry consisting of a circle inside a square. Then i extruded my geometry with 1 layer to have a 2D problem. Here my .geo file: // Gmsh project created on Tue Jan 4 16:30:24 2011 lc = 0.0001; d1 = 0.001; r = 0.00014142; c = 0.0005; Point(1)={0, 0, 0, lc}; Point(2)={d1-0.0003, 0, 0, lc}; Point(3)={d1-0.0003, d1-0.0003, 0, lc}; Point(4)={0, d1-0.0003, 0, lc}; Point(5)={c+r-0.00015, c+r-0.00015, 0, lc}; Point(6)={c+r-0.00015, c-r-0.00015, 0, lc}; Point(7)={c-r-0.00015, c-r-0.00015, 0, lc}; Point(8)={c-r-0.00015, c+r-0.00015, 0, lc}; Point(9)={c-0.00015, c-0.00015, 0, lc}; Circle(1) = {5, 9, 8}; Circle(2) = {8, 9, 7}; Circle(3) = {7, 9, 6}; Circle(4) = {6, 9, 5}; Line(5) = {2, 3}; Line(6) = {3, 4}; Line(7) = {4, 1}; Line(8) = {1, 2}; Line Loop(9) = {1, 2, 3, 4}; Ruled Surface(10) = {9}; Line Loop(11) = {7, 8, 5, 6}; Plane Surface(12) = {11,9}; Extrude {0, 0, 0.00001} { Surface{12}; Layers{1}; Recombine; } Extrude {0, 0, 0.00001} { Surface{10}; Layers{1}; Recombine; } Physical Surface("top") = {37}; Physical Surface("bottom") = {29}; Physical Surface("left") = {25}; Physical Surface("right") = {33}; Physical Surface("front") = {54}; Physical Surface("back") = {12}; Physical Surface("obstacle") = {53, 49, 45, 41}; Physical Volume("internal") = {1}; OpenFoam impot the geometry without any problem and if i do CheckMesh everything is ok. I run the simulation (fluid enter on the top and displace another fluid) but something strange happens. The flow stops when it reaches exactly one of the points used to define the circle (point 5). When I built the mesh I used the option "Mesh from curvature" in the mesh option in order to have these 4 (8 in 2D) points on the circle exactly on the edges of the prisms and not on the side but i got the same problem if I do not. Maybe is a problem with boundary condition because i have to define 4 surfaces on the disc and not only one, but all 4 have the same patch "wall". Is there a way to define a single surface or otherwise any suggestion to solve the problem?? Thanks Andrea

 January 6, 2011, 08:34 #2 Senior Member   Andrea Ferrari Join Date: Dec 2010 Posts: 319 Rep Power: 15 I solved it!