# To replace Gmsh **URL:** \ **Category:** General Discussion\ **Created:** [January 30, 2025, 4:10pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716 "2025-01-30T16:10:52Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 30, 2025, 4:10pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/1 "2025-01-30T16:10:52Z")
Hi all, In FreeFEM I have problems reading meshes generated by Gmsh as soon as there are labelled surfaces (e.g. Physical Surface(“inlet”, 26) = {7};). Reading the posts in this forum, I have the feeling that no solution has been yet identified (?). Am I right concerning the problem with labelled surfaces in Gmsh (my version is v4.11.1) ? Is there another open source candidate to replace Gmsh ? Thanks Dominique ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 30, 2025, 5:19pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/2 "2025-01-30T17:19:28Z")
Could you please share a small mesh example reproducing the behavior? ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 31, 2025, 7:06am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/3 "2025-01-31T07:06:03Z")
Below the gmsh geo file: SetFactory(“OpenCASCADE”); // Parameters r\_cylinder = 0.2; // Radius of the main cylinder h\_cylinder = 1.0; // Height of the main cylinder r\_inlet = 0.05; // Radius of the inlet pipe h\_inlet = 0.3; // Length of the inlet pipe r\_outlet\_gas = 0.04; // Radius of the gas outlet pipe h\_outlet\_gas = 0.4; // Length of the gas outlet pipe r\_outlet\_liquid = 0.04; // Radius of the liquid outlet pipe h\_outlet\_liquid = 0.3; // Length of the liquid outlet pipe // Main cylinder Cylinder(1) = {0, 0, 0, 0, 0, h\_cylinder, r\_cylinder, 2\*Pi}; // Tangential inlet pipe inlet\_offset = r\_cylinder - r\_inlet; // Offset to ensure tangential alignment Cylinder(2) = {0, inlet\_offset, 2 \* h\_cylinder / 3, h\_inlet, 0, 0, r\_inlet, 2\*Pi}; // Gas outlet pipe //Cylinder(3) = {0, 0, h\_cylinder + h\_outlet\_gas, 0, 0, -h\_outlet\_gas, r\_outlet\_gas, 2_Pi}; Cylinder(3) = {0, 0, h\_cylinder, 0, 0, h\_outlet\_gas, r\_outlet\_gas, 2_Pi}; // Liquid outlet pipe Cylinder(4) = {0, 0, -h\_outlet\_liquid, 0, 0, h\_outlet\_liquid, r\_outlet\_liquid, 2\*Pi}; BooleanUnion(20) = { Volume{1}; Delete; }{ Volume{2}; Delete; }; BooleanUnion(21) = { Volume{20}; Delete; }{ Volume{3}; Delete; }; BooleanUnion(22) = { Volume{21}; Delete; }{ Volume{4}; Delete; }; ## Physical Surface(“inlet”, 26) = {7}; Physical Surface(“liqoutlet”, 28) = {8}; Physical Surface(“gasoutlet”, 23) = {9}; In freefem, I tried to read directly the msh file: mesh3 Th = gmshload3(“glcc.msh”); or to generate it: lockOrientation = false; system(“gmsh -format msh22 -3 -o glcc.msh glcc.geo”); mesh3 Th = gmshload3(“glcc.msh”); lockOrientation = true; Thanks ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 31, 2025, 7:06am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/4 "2025-01-31T07:06:25Z")
Can’t copy/paste your code =\> can’t help. Put everything in between code blocks. ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 31, 2025, 7:08am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/5 "2025-01-31T07:08:15Z")
hoping it’s getting better ```auto SetFactory("OpenCASCADE"); // Parameters r_cylinder = 0.2; // Radius of the main cylinder h_cylinder = 1.0; // Height of the main cylinder r_inlet = 0.05; // Radius of the inlet pipe h_inlet = 0.3; // Length of the inlet pipe r_outlet_gas = 0.04; // Radius of the gas outlet pipe h_outlet_gas = 0.4; // Length of the gas outlet pipe r_outlet_liquid = 0.04; // Radius of the liquid outlet pipe h_outlet_liquid = 0.3; // Length of the liquid outlet pipe // Main cylinder Cylinder(1) = {0, 0, 0, 0, 0, h_cylinder, r_cylinder, 2*Pi}; // Tangential inlet pipe inlet_x_offset = r_cylinder - r_inlet; // Offset to ensure tangential alignment Cylinder(2) = {0, inlet_x_offset, 2 * h_cylinder / 3, h_inlet, 0, 0, r_inlet, 2*Pi}; // Gas outlet pipe //Cylinder(3) = {0, 0, h_cylinder + h_outlet_gas, 0, 0, -h_outlet_gas, r_outlet_gas, 2*Pi}; Cylinder(3) = {0, 0, h_cylinder, 0, 0, h_outlet_gas, r_outlet_gas, 2*Pi}; // Liquid outlet pipe Cylinder(4) = {0, 0, -h_outlet_liquid, 0, 0, h_outlet_liquid, r_outlet_liquid, 2*Pi}; BooleanUnion(20) = { Volume{1}; Delete; }{ Volume{2}; Delete; }; BooleanUnion(21) = { Volume{20}; Delete; }{ Volume{3}; Delete; }; BooleanUnion(22) = { Volume{21}; Delete; }{ Volume{4}; Delete; }; Physical Surface("inlet", 26) = {7}; Physical Surface("liqoutlet", 28) = {8}; Physical Surface("gasoutlet", 23) = {9}; ``` ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 31, 2025, 7:33am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/6 "2025-01-31T07:33:01Z")
You have not defined the volume to mesh, so Gmsh is not producing a 3D mesh. ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 31, 2025, 7:34am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/7 "2025-01-31T07:34:57Z")
The surface is also not well-defined: ```auto Info : - Creating surface mesh Info : Found two duplicated facets. Info : 1st: [62, 137, 142] #5 Info : 2nd: [62, 137, 142] #5 Error : Invalid boundary mesh (overlapping facets) on surface 5 surface 5 Error : No elements in volume 22 Info : Done meshing 3D (Wall 0.00305525s, CPU 0.00282s) Info : 183 nodes 436 elements Error : ------------------------------ Error : Mesh generation error summary Error : 0 warnings Error : 2 errors Error : Check the full log for details Error : ------------------------------ ``` ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 31, 2025, 7:58am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/8 "2025-01-31T07:58:16Z")
Thank prj, I’m going to investigate ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 31, 2025, 11:23am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/9 "2025-01-31T11:23:06Z")
the code below does not provide errors. FreeFem is able to load, but it detects only one label instead of three: ```auto SetFactory("OpenCASCADE"); DefineConstant[ N = {10, Name "input/1N"}, Li = {0.2, Name "input/2length inlet "}, ri = {0.05, Name "input/3radius inlet "}, hi = {1.0, Name "input/4height inlet "}, Lg = {0.2, Name "input/5length gas out "}, rg = {0.05, Name "input/6radius gas out "}, Ll = {0.2, Name "input/7length liquid out "}, rl = {0.05, Name "input/8radius liquid out "}, Lc = {1, Name "input/9length cylinder "}, rc = {0.2, Name "input/10radius cylinder "} ]; Cylinder(1) = {0, 0, 0, 0, 0, Ll, rl, 2*Pi}; Cylinder(2) = {0, 0, Ll, 0, 0, Lc, rc, 2*Pi}; Cylinder(3) = {0, 0, Ll+Lc, 0, 0, Lg, rg, 2*Pi}; Cylinder(4) = {-Li, rc-ri, hi, Li, 0, 0, ri, 2*Pi}; //+ BooleanUnion(5) = { Volume{2}; Delete; }{ Volume{4}; Delete; }; BooleanUnion(6) = { Volume{5}; Delete; }{ Volume{1}; Delete; }; BooleanUnion(7) = { Volume{6}; Delete; }{ Volume{3}; Delete; }; //+ Physical Surface("inlet", 14) = {7}; Physical Surface("liquid", 15) = {8}; Physical Surface("gas", 16) = {9}; ``` ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 31, 2025, 1:53pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/10 "2025-01-31T13:53:40Z")
You still have no physical volume, so this can’t be used for a `mesh3`. ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [January 31, 2025, 2:12pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/11 "2025-01-31T14:12:38Z")
same behavior when adding the following line : ```auto Physical Volume("glcc", 17) = {7}; ``` To check whether the labels are considered, I have written the following in the edp file: ```auto int[int] labs = labels(Th); cout << "List of labelled surfaces:" << endl; for (int i = 0; i < labs.n; i++) { cout << "Label: " << labs[i] << endl; } ``` ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [January 31, 2025, 2:42pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/12 "2025-01-31T14:42:13Z")
We are starting to get somewhere. Your mesh is not a closed surface, you are missing surface elements everywhere outside of your current three labels. ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [February 4, 2025, 8:27am UTC](https://community.freefem.org/t/to-replace-gmsh/3716/13 "2025-02-04T08:27:03Z")
prj, thanks for your feedback. Below a version where a volume is defined, including all the elements (I think so), but still only one label detected with freefem++. ```auto SetFactory("OpenCASCADE"); DefineConstant[ N = {10, Name "input/1N"}, Li = {0.2, Name "input/2length inlet "}, ri = {0.05, Name "input/3radius inlet "}, hi = {1.0, Name "input/4height inlet "}, Lg = {0.2, Name "input/5length gas out "}, rg = {0.05, Name "input/6radius gas out "}, Ll = {0.2, Name "input/7length liquid out "}, rl = {0.05, Name "input/8radius liquid out "}, Lc = {1, Name "input/9length cylinder "}, rc = {0.2, Name "input/10radius cylinder "} ]; Cylinder(1) = {0, 0, 0, 0, 0, Ll, rl, 2*Pi}; Cylinder(2) = {0, 0, Ll, 0, 0, Lc, rc, 2*Pi}; Cylinder(3) = {0, 0, Ll+Lc, 0, 0, Lg, rg, 2*Pi}; Cylinder(4) = {-Li, rc-ri, hi, Li, 0, 0, ri, 2*Pi}; //+ BooleanUnion(5) = { Volume{2}; Delete; }{ Volume{4}; Delete; }; Coherence; Physical Volume("glcc", 17) = {3, 5, 1}; Physical Surface("liquid", 18) = {3}; Physical Surface("gas", 19) = {8}; Physical Surface("inlet", 20) = {14}; ``` ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [February 4, 2025, 12:03pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/14 "2025-02-04T12:03:32Z")
This is still not a closed surface. ![Screenshot 2025-02-04 at 1.03.01 PM](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/e/e40216ec3f09e13feb8dc75003cc8de45fc856cd.jpeg) ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [February 4, 2025, 1:14pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/15 "2025-02-04T13:14:51Z")
Sorry to bother again. I guess that I have now closed surface (?), but still problem of label with freefem++. ```auto SetFactory("OpenCASCADE"); DefineConstant[ N = {10, Name "input/1N"}, Li = {0.2, Name "input/2length inlet "}, ri = {0.05, Name "input/3radius inlet "}, hi = {1.0, Name "input/4height inlet "}, Lg = {0.2, Name "input/5length gas out "}, rg = {0.05, Name "input/6radius gas out "}, Ll = {0.2, Name "input/7length liquid out "}, rl = {0.05, Name "input/8radius liquid out "}, Lc = {1, Name "input/9length cylinder "}, rc = {0.2, Name "input/10radius cylinder "} ]; Cylinder(1) = {0, 0, 0, 0, 0, Ll, rl, 2*Pi}; Cylinder(2) = {0, 0, Ll, 0, 0, Lc, rc, 2*Pi}; Cylinder(3) = {0, 0, Ll+Lc, 0, 0, Lg, rg, 2*Pi}; Cylinder(4) = {-Li, rc-ri, hi, Li, 0, 0, ri, 2*Pi}; //+ BooleanUnion(5) = { Volume{2}; Delete; }{ Volume{4}; Delete; }; Coherence; Physical Volume("glcc", 22) = {3, 5, 1}; Physical Surface("liquid", 18) = {3}; Physical Surface("gas", 19) = {8}; Physical Surface("inlet", 20) = {14}; Physical Surface("wall", 21) = {12, 7, 10, 13, 11, 1}; ``` ![closedsurface](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/0/0f9115fd48c7124454538651674a57c501ba8864.png) ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [February 4, 2025, 2:09pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/16 "2025-02-04T14:09:16Z")
And what is the problem precisely? Here is what I get as list of labels with your mesh. ```auto 4 18 19 20 21 ``` This is OK, isn’t it? ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [February 4, 2025, 2:25pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/17 "2025-02-04T14:25:43Z")
You got those labels using freefem++ ? Below is how I check the labels using freefem++, it might be an error ```auto load "msh3" load "gmsh" load "medit" mesh3 Th = gmshload3("glcc.msh"); plot(Th,wait=1); int[int] labs = labels(Th); cout << "List of labelled surfaces:" << endl; for (int i = 0; i < labs.n; i++) { cout << "Label: " << labs[i] << endl; } medit("glcc",Th,wait=1); ``` ---
**Author:** ![dominiquebodin](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@dominiquebodin](https://community.freefem.org/u/dominiquebodin)\ **Post date:** [February 4, 2025, 2:39pm UTC](https://community.freefem.org/t/to-replace-gmsh/3716/18 "2025-02-04T14:39:55Z")
I’ve been able to retrieve the labels using the lines: ```auto lockOrientation = false; system("gmsh -format msh22 -3 -o glcc.msh glcc.geo"); mesh3 Th = gmshload3("glcc.msh"); lockOrientation = true; ``` prj, many thanks for your patience, you helped a lot