Hi Christophe, Thanks for the prompt reply. I have tried the Extrude option for boundary layer. It works perfect. But the normal direction is the issue.
I am working on a project where my input geometry is always in .stl format and I create compound surfaces to generate surface mesh. During this process, the normal direction is disturbed or random, even if I provide the input stl with normal facing inward. I can add a -ve sign for the outward facing surfaces, while extruding boundary layer. But I want to write a generic code that works fine for all the stl geometries I import. Is there a way to re-orient all the surface normals inwards? Best regards Praveen On Thu, Sep 15, 2016 at 1:13 PM, Christophe Geuzaine <[email protected]> wrote: > > Dear Praveen, > > The Boundary Layer field was an experiment: the 3D version was not > functional and has been removed in recent versions. The 2D version is > fairly usable. New implementation of boundary layers are forthcoming. In > 3D, I currently advise simply using the Extrude command: it will not create > fans, but for simple geometries like yours it should be sufficient. > > Here's an example: > > // create a square > lc = 0.3; > Point(1) = {0.0,0.0,0.0,lc}; > Point(2) = {1,0.0,0.0,lc}; > Point(3) = {1,1,0.0,lc}; > Point(4) = {0,1,0.0,lc}; > Line(1) = {4,3}; > Line(2) = {3,2}; > Line(3) = {2,1}; > Line(4) = {1,4}; > Line Loop(1) = {2,3,4,1}; > Plane Surface(1) = {1}; > > // create a cube > Extrude {0,0.0,1} { Surface{1}; } > > // remove the volume > Delete { Volume{1}; } > > // extrude the boundary of the cube inwards by 0.05, with 5 layers of > elements > Extrude { Surface{26, -1, 13, 17, 21, 25}; Layers{5, 0.05}; } > > // create the inner volume > Surface Loop(159) = {92, 158, 70, 48, 136, 114}; > Volume(160) = {159}; > > General.ExpertMode = 1; // disable warning about mixing Delaunay and > extrusion > > > > > On 14 Sep 2016, at 10:52, Praveen Kumar <[email protected]> wrote: > > > > Hi, > > > > I am trying to generate boundary layers on all the surfaces of a simple > rectangular duct geometry (imported stl). The prism layers are not getting > connected on the edges/corners between each surfaces. > > > > <BL-issue.JPG> > > > > > > Can someone help me understand what is missing here? Please Note, I am > using 2.11.0 version of gmsh as this is not working at all in the latest > version > > > > -------------------------------------- > > Merge "duct.stl"; > > CreateTopology; > > > > ll[] = Line "*"; > > l = newl; > > For j In {0 : #ll[]-1} > > Compound Line(l+j) = ll[j]; > > EndFor > > > > ss[] = Surface "*"; > > s = news; > > For i In {0 : #ss[]-1} > > Compound Surface(s+i) = ss[i]; > > EndFor > > > > bl = newl; > > bs = news; > > > > Field[1] = MathEval; > > Field[1].F = "0.1"; > > > > Background Field = 1; > > > > Mesh.CharacteristicLengthExtendFromBoundary = 0; > > > > Physical Surface("Side-01") = {s}; > > Physical Surface("Top") = {s+1}; > > Physical Surface("Side-02") = {s+2}; > > Physical Surface("Outlet") = {s+3}; > > Physical Surface("Bottom") = {s+4}; > > Physical Surface("Inlet") = {s+5}; > > > > sl = newsl; Surface Loop(sl) = {s:s+5}; > > vo = newv; Volume(vo) = {sl}; > > > > //Physical Volume("V_Fluid") = {vo}; > > > > pp[] = Point "*"; > > > > Field[2] = BoundaryLayer; > > //Field[2].AnisoMax = 60; > > Field[2].FacesList = {s:bs-1}; > > Field[2].EdgesList = {l:bl-1}; > > Field[2].NodesList = {pp[0]:pp[7]}; > > //Field[2].FanNodesList = {pp[0]:pp[7]}; > > //Field[2].IntersectMetrics = 0; > > //Field[2].Quads = 0; > > //Field[2].hfar = 0.1; > > Field[2].hwall_n = 0.025; > > //Field[2].hwall_t = 0.1; > > Field[2].ratio = 1.1; > > Field[2].thickness = 0.05; > > BoundaryLayer Field = 2; > > //Background Field = 2; > > > > ---------------------------------------------- > > > > -- > > Praveen Kumar R | Technical Manager > > Centre for Computational Technologies - CCTech > > 1 Akshay Residancy | 50 Anand Park | Aundh | Pune | 411007 | India > > Ph: +91 20 40098381/82 | M: +91-9923406816 | www.cctech.co.in > > CCTech – "Transforming human life by democratization of technology" > > > > > > <duct.geo><duct.stl><BL-issue.JPG>__________________________ > _____________________ > > gmsh mailing list > > [email protected] > > http://onelab.info/mailman/listinfo/gmsh > > -- > Prof. Christophe Geuzaine > University of Liege, Electrical Engineering and Computer Science > http://www.montefiore.ulg.ac.be/~geuzaine > > Free software: http://gmsh.info | http://getdp.info | http://onelab.info > > -- Praveen Kumar R | Technical Manager *Centre for Computational Technologies - CCTech * 1 Akshay Residancy | 50 Anand Park | Aundh | Pune | 411007 | India Ph: +91 20 40098381/82 | M: +91-9923406816 | www.cctech.co.in *CCTech – "* *Transforming human life by democratization of technology"*
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