[Gmsh] Fan error in BL high order mesh

Alberto d039007 at polito.it
Tue Feb 6 14:31:26 CET 2018


Dear Gmsh-list,


I'm using Gmsh 2.10.1 to create a 2D mesh for a CFD viscous analisys of 
a turbine vane.

To create the mesh I've used Delaunay for quad (2D algorithm) and 
Blossom (2D recombination algorithm).

I've a problem with the 2° order grid, in the boundary layer, near the 
fan. The second order grid creates a strange element that isn't a hole 
or an element with zero volume and there aren't warning or error during 
the grid creation process. You could see in the file.png what's happen.

The same problem happen with different 2D algorithm or recombination 
algorithm and also with the version 3.0.2.

You could find the file.geo (and the file Profilo.dat with the point's 
coordinates) to create the mesh, the file.msh with the problem and also 
some pictures with the details of the cells near the fan.

Have anyone seen something like this?

Thank you for your help!

Alberto
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// ATTENZIONE: USARE GMSH 2.11.0, 2d ALGORITHM = FRONTAL, 2D RECOMB. ALG. = STANDARD



alpha=75/57.3;
alpha2=60/57.3;
h=0.2;
periodo=60.028889999999997-34.780360000000002;
cordax= 9.9999909999999996;
lcw=0.04*cordax;
lcff=0.16*cordax;
Include "Profilo.dat";

BSpline(10) = {1:4,13,17,18};
Line(9) = {18:19};
Line(5) = {1,247};
BSpline(8) = {19,25,150,180,210,230,240:247};


delta=10;

Point(10001) = { -cordax, -cordax*Tan(alpha2)-delta, 0.0000000, 2*lcff};
Point(10002) = { -cordax, -cordax*Tan(alpha2)+periodo-delta, 0.0000000, 2*lcff};
Point(10004) = { 0.6*cordax, -cordax*Tan(alpha2)-delta+1.6*cordax*Tan(alpha2), 0.0000000, lcff};
Point(10003) = { 0.6*cordax, -cordax*Tan(alpha2)-delta+1.6*cordax*Tan(alpha2)+periodo, 0.0000000, lcff};
Point(10005) = { 2*cordax, 2*cordax*Tan(alpha)-delta, 0.0000000, lcff};
Point(10006) = { 2*cordax, 2*cordax*Tan(alpha)+periodo-delta, 0.0000000, lcff};


Point(10007) = { 0.6*cordax+0.25*cordax,0.85*cordax*Tan(alpha)-delta-0.6*cordax*Tan(alpha2)+0.3, 0.0,2*lcff};
Point(10008) = { 0.6*cordax+cordax/250, -cordax*Tan(alpha2)-delta+1.6*cordax*Tan(alpha2)+Tan(alpha)*cordax/250, 0.0000000, 2*lcff};
Point(10009) = { 0.06*cordax, 0.06*cordax*Tan(alpha2)-delta, 0.0000000, 2*lcff};
Point(10010) = { -0.1*cordax, -0.1*cordax*Tan(alpha2)-delta, 0.0000000, 2*lcff};
Point(10011) = { cordax, 34.780360000000002-0.5, 0.0000000, lcff};

Line(1) = {10001,10002};
Line(2) = {10002,10003};
Line(3) = {10003,10006};
Line(4) = {10006,10005};
Line(6) = {10005,10004};
Line(7) = {10004,10001};

Periodic Line { 2} = {-7};
Periodic Line { 3} = {-6};


//Define bounding box outer boundary
Line Loop(101) = {1, 2,3,4,6,7};

//Define foil boundary
Line Loop(102) = {10,9,8,-5};


Plane Surface(201) = {101, 102};



//Define physical surfaces - numeric designations from GUI
Physical Surface(1) = {201};	//superficie fluida
Physical Line(33) = {1};	//inlet
Physical Line(22) = {4}; 	//outlet
Physical Line(99) = {9,10,5,8};	//adiabatic solid wall
Physical Line(105) = {2,3};	//perio2
Physical Line(106) = {6,7};	//perio1

Transfinite Line{1} = 20 Using Progression 1.0;
Transfinite Line{4} = 20 Using Progression 1.0;

Field[6]         = Cylinder ;
Field[6].XCenter = cordax;
Field[6].YCenter = 34.780360000000002;
Field[6].ZCenter = 0.000000e+00;
Field[6].XAxis = 0.000000e+00;
Field[6].YAxis = 0.000000e+00;
Field[6].ZAxis = 1;
Field[6].Radius = 2.3;
Field[6].VIn = 0.5*lcw;
Field[6].VOut =lcff;

Field[22] = Attractor;
Field[22].NodesList = {1,247};

Field[33] = Threshold;
Field[33].IField = 22;
Field[33].LcMin = 0.15*lcw;
Field[33].LcMax = lcff;
Field[33].DistMin = 0.05;
Field[33].DistMax = 0.5;


Field[4] = Attractor;
Field[4].NNodesByEdge = 50000;
Field[4].EdgesList = {9,10,8,5};

Field[5] = Threshold;
Field[5].IField = 4;
Field[5].LcMin = 0.331*lcw;
Field[5].LcMax = lcff;
Field[5].DistMin = 0.05;
Field[5].DistMax = 2;

Field[14] = Attractor;
Field[14].NNodesByEdge = 5000;
Field[14].EdgesList = {5};

Field[15] = Threshold;
Field[15].IField = 14;
Field[15].LcMin = 0.1*lcw;
Field[15].LcMax = lcff;
Field[15].DistMin = 0.3;
Field[15].DistMax = 2;


Line(202)={10007,10004};
Line(200)={10004,10010};
Field[18] = Attractor;
Field[18].NNodesByEdge = 1000;
Field[18].EdgesList = {200,202};

Field[19] = Threshold;
Field[19].IField = 18;
Field[19].LcMin = 0.55*lcw;
Field[19].LcMax = lcff;
Field[19].DistMin = 0.01;
Field[19].DistMax = 2;

//Field[10] = MathEval;
//Field[10].F = "Max(0.1,0.2)";


Line(15) = {1,10011};
Field[26] = Attractor;
Field[26].NNodesByEdge = 4000;
Field[26].EdgesList = {15};

Field[37] = Threshold;
Field[37].IField = 26;
Field[37].LcMin = 0.0009*cordax;
Field[37].LcMax = lcff;
Field[37].DistMin = 0.001;
Field[37].DistMax = 0.05;


//Define Boundary Layer
Field[1] = BoundaryLayer;
Field[1].EdgesList = {5, 8,10,9};
Field[1].FanNodesList = {1,247,18,19};
Field[1].hwall_n = 0.000035*cordax;
Field[1].thickness = 0.0027*cordax;
Field[1].ratio = 1.2;
Field[1].AnisoMax = 5;
Field[1].Quads = 1;
Field[1].IntersectMetrics = 0;
BoundaryLayer Field = 1;



Field[7] = Min;
Field[7].FieldsList = {8,6,3,5,10,15,17,19,34,33,35,36,37};
Background Field = 7;

Coherence;
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 Point(           1 )={   9.9999909999999996      ,   34.780360000000002      ,0,lcw};
 Point(           2 )={   9.8694620000000004      ,   34.378639999999997      ,0,lcw};
 Point(           3 )={   6.7950840000000001      ,   24.916670000000000      ,0,lcw};
 Point(           4 )={   6.7913329999999998      ,   24.905130000000000      ,0,lcw};
 Point(          13 )={   1.2988430000000000      ,   14.125510000000000      ,0,lcw};
 Point(          17 )={   6.6970824999999998E-002 ,   12.187290000000001      ,0,lcw};
 Point(          18 )={  -9.5367432000000010E-007 ,   11.710760000000001      ,0,lcw};
 Point(          19 )={   0.0000000000000000      ,   0.0000000000000000      ,0,lcw};
 Point(          25 )={   1.5131530000000000      ,  -2.2433429999999999      ,0,lcw};
 Point(         150 )={   4.8530980000000001      ,   4.0859990000000002      ,0,lcw};
 Point(         180 )={   4.7250719999999999      ,   9.6237309999999994      ,0,lcw};
 Point(         210 )={   5.5835710000000001      ,   17.290250000000000      ,0,lcw};
 Point(         230 )={   7.2396380000000002      ,   24.753430000000002      ,0,lcw};
 Point(         240 )={   8.6221390000000007      ,   29.524260000000002      ,0,lcw};
 Point(         241 )={   8.7870570000000008      ,   30.047329999999999      ,0,lcw};
 Point(         242 )={   8.9572979999999998      ,   30.579170000000001      ,0,lcw};
 Point(         243 )={   9.0296439999999993      ,   30.793930000000000      ,0,lcw};
 Point(         244 )={   9.2722309999999997      ,   31.540540000000000      ,0,lcw};
 Point(         245 )={   9.5148189999999992      ,   32.287149999999997      ,0,lcw};
 Point(         246 )={   9.7574059999999996      ,   33.033760000000001      ,0,lcw};
 Point(         247 )={   9.9999939999999992      ,   33.780360000000002      ,0,lcw};
 Point(         248 )={   9.9999909999999996      ,   34.780360000000002      ,0,lcw};



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