@Markiyan Hirnyk It's not in the code. The difficulty is for example create a mesh with more accuracy in the one border, resolve a PDE with Neumman resolution/solution, apply the contour conditions. 

For create a mesh

Needs["NDSolve`FEM`"] 

Minarea = 10^-5 L H (* LH = Área que ocupa la pieza *);
Maxarea = 10^-3 L H;
g = Function[{vertices, area},
Block[{x, y}, {x, y} = Mean[vertices];
area > (Maxarea - Minarea)/H y + Minarea]];
mesh = ToElementMesh[FullRegion[2], {{-L/2, L/2}, {0, H}},
"MeshElementType" -> TriangleElement, MeshRefinementFunction -> g,
MeshQualityGoal -> "Maximal"];

Operator

op = k \!\(
\*SubsuperscriptBox[\(\[Del]\), \({x, y}\), \(2\)]\(T[x, y]\)\) +
Subscript[v, d] \!\(
\*SubscriptBox[\(\[PartialD]\), \(x\)]\(T[x, y]\)\);

This is some example of the program. Someone can help me?