[Gmsh] Different threshold fields around one attractor

[Moritz Nadler]

Hallo,

I still do not know how to do it. Maybe my question was badly formulated, so I 
retry:

What I want is a mesh density around a an area that goes like this:


Mesh density
^
| ----------------
|                 \
|                  \
|                   \
|                    -----------
|                               \
|                                \
|                                 \
|                                  -------------
|
|                 ^ DistMin 1
|                     ^ DistMax 1
|                               ^ DistMin 2
|                                  ^ DistMax 2
_________________________________________________> Distance from attractor

This is what I tried to get it:

Field[2] = Threshold;
Field[2].IField = 1;
Field[2].LcMin = 0.001;
Field[2].LcMax = 0.005;
Field[2].DistMin = 0.05;
Field[2].DistMax = 0.2;

Field[3] = Attractor;
Field[3].NodesList = {5};

Field[4] = Threshold;
Field[4].IField = 3;
Field[4].LcMin = 0.005;
Field[4].LcMax = 0.1;
Field[4].DistMin = 0.3;
Field[4].DistMax = 0.5;

Field[5] = Min;
Field[5].FieldsList = {2,4};

Background Field = 5;

But it does not work. It creates only ONE area with higher density around the 
point 5.

What do have have to do to make it work?



thanks it advance and

kind regards

Moritz Nadler


Moritz Nadler wrote:
> Hallo,
> 
> I want to have 2 threshold fields around one attractor so I get get
> one area with very fine mesh directly around the attractor point
> from the attractor point to the DistMin value of the inner threshold field.
> Then a linear mesh density gradient from the DistMin to DistMax value of 
> the first threshold field where at DistMax the mesh density of the 
> second threshold field is reached and stays until the DistMin value of 
> the second threshold is reached
> And then a linear density gradient from DistMin to DistMax of the second 
> threshold field.
> 
> What I thourght is the obvous way to do this did not work:
> 
> Field[1] = Attractor;
> Field[1].NodesList = {5};
> 
> Field[2] = Threshold;
> Field[2].IField = 1;
> Field[2].LcMin = 0.001;
> Field[2].LcMax = 0.005;
> Field[2].DistMin = 0.05;
> Field[2].DistMax = 0.2;
> 
> Field[3] = Attractor;
> Field[3].NodesList = {5};
> 
> Field[4] = Threshold;
> Field[4].IField = 3;
> Field[4].LcMin = 0.005;
> Field[4].LcMax = 0.1;
> Field[4].DistMin = 0.3;
> Field[4].DistMax = 0.5;
> 
> Field[5] = Min;
> Field[5].FieldsList = {2,4};
> 
> Background Field = 5;
> 
> Because only when both threshold fields have the same LcMax value I get 
> 2 circles around the attractor point. If I use the above posted values 
> the general mesh denstiy is way to high and there is only one circle in 
> the middle.
> 
> Does anybody know what the right gmsh semantics for my problem are?
> 
> 
> kind regards
> 
> 
> Moritz
> 
> 
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> 
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