gmsh_cheatsheet

Short overview of basic commands in gmsh. The official manual you can find here

Geometry

Points

create point id

// <IDENTIFIER> = newp;
P1 = newp;

create point

// Point(<POINT_ID>) = {<X>, <Y>, <Z>};
Point(P1) = {1.0, 0.0, 0.0};

get coordinates of a point

// <IDENTIFIER>[] = Point{<POINT_ID>};
coordinates[] = Point{P1};

Curves

create new line id

// <IDENTIFIER> = newl;
L1 = newl;

create line

// Line(<LINE_ID>) = {<POINT_1_ID>, <POINT_2_ID>};
Line(L1) = {P1, P2};

create new line loop id

// <IDENTIFIER> = newll;
LL1 = newll;

create new line loop

Creating a line loop demands that the are continous and direction can not be neglected.

// Curve Loop(<LINE_LOOP_ID>) = {<LINE_1_ID>, ..., <LINE_N_ID>};
Curve Loop(LL1) = {L1, L2, L3};

get points of a line

// <IDENTIFIER>[] = PointsOf{Line{<LINE_1_ID>, ..., <LINE_N-1_ID>}; Line{<LINE_N_ID>}; };
line_points[] =  PointsOf{
  Line{
    L1,
    L2
  };
  Line{L3};
};

Surfaces

create new surface id

// <IDENTIFIER> = news;
S1 = news;

create new surface

// Surfaces(<SURFACE_ID> = {<LINE_LOOP_ID>})
Surface(S1) = {LL1};

get points of a surface

// <IDENTIFIER>[] = PointsOf{Surface{<SURFACE_1_ID>, ..., <SURFACE_N-1_ID>}; Surface{<SURFACE_N_ID>}; };
surface_points[] = PointsOf{
  Surface{
    S1,
    S2
  };
};

Volumes

create new volume id

// <IDENTIFIER> = newv;
V1 = newv;

create new volume

// Volume(<VOLUME_ID>) = {<SURFACE_LOOP_ID>};
 Volume(V1) = {SL1};

Miscellaneous

Print to terminal

print text to terminal

  // Printf("<TEXT>");
  Printf("Hello Wourld!");

print variable to terminal

  // Printf("<FORMATTING_CHARACTER>", <>);
  Printf("%g", V1);

Lists

define a list

// <IDENTIFIER>[] = {<ITEM_1>, ..., <ITEM_N>};
  list[] = {4, 6, 8, 10, 12, 14};

access a single item from a list

  // <IDENTIFIER>[<ITEM_ID>];
  list_item = list[0];

access a sequence of items from a list

  // <IDENTIFIER>[{<ITEM_1>:<ITEM_N>:<SEQUENCE_STEP>}];
  list1[] = list[{0:5}]; // 4, 6, 8, 10, 12, 14
  list2[] = list[{0:5:2}]; // 4, 8, 12

access all items form a list

  // <IDENTIFIER>[];
  list3[] = list[];

get the size of a list

  // #<LIST>[];
  size_list = #list[];

Mesh

Structured Mesh

create structured mesh for a 1D element

// Transfinite Curve {<CURVE_1_ID>, ... <CURVE_N_ID>} = <NUMBER_OF_NODES> Using Progression <PROGRESSION_FACTOR> []
Transfinite Curve {L1, L2, L3, L4, L5, L6} = 10 Using Progression 1;

create structures mesh for a 2D element

// Transfinite Surface {<SURFACE_ID>} = [{<POINT_1_ID>, <POINT_2_ID>, <POINT_3_ID> [, <POINT_4_ID>]}]
Transfinite Surface {S1} = {P1, P2, P3};