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Merge branch 'vgeza_fix_blayer_limiting' into 'master'
Boundary layer thickness limiting fixes See merge request ngsolve/netgen!596
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3ff2e46ddd
@ -42,15 +42,26 @@ namespace netgen
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if(!isIntersectingPlane(seg, trig, lam))
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return false;
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//buffer enlargement of triangle
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auto pt0 = trig[0];
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auto pt1 = trig[1];
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auto pt2 = trig[2];
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Point<3> center = { (pt0[0] + pt1[0] + pt2[0]) / 3.0, (pt0[1] + pt1[1] + pt2[1]) / 3.0, (pt0[2] + pt1[2] + pt2[2]) / 3.0 };
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array<Point<3>, 3> larger_trig = {
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center + (pt0 - center) * 1.1,
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center + (pt1 - center) * 1.1,
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center + (pt2 - center) * 1.1, };
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auto p = seg[0] + lam/0.9*(seg[1]-seg[0]);
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auto n_trig = Cross(trig[1]-trig[0], trig[2]-trig[0]).Normalize();
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for(auto i : Range(3))
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{
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// check if p0 and p are on same side of segment p1-p2
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auto p0 = trig[i];
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auto p1 = trig[(i+1)%3];
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auto p2 = trig[(i+2)%3];
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auto p0 = larger_trig[i];
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auto p1 = larger_trig[(i+1)%3];
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auto p2 = larger_trig[(i+2)%3];
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auto n = Cross(p2-p1, n_trig);
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auto v0 = (p2-p1).Normalize();
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@ -147,6 +158,91 @@ namespace netgen
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limits.SetSize(np);
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limits = 1.0;
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// Function to calculate the dot product of two 3D vectors
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// Is there netgen native function for this?
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const auto Dot = [](Vec<3> a, Vec<3> b) {
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return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
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};
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auto parallel_limiter = [&](PointIndex pi1, PointIndex pi2, SurfaceElementIndex si) {
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MeshPoint& a_base = mesh[pi1];
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MeshPoint& b_base = mesh[pi2];
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MeshPoint a_end = mesh[pi1] + height * limits[pi1] * growthvectors[pi1];
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MeshPoint b_end = mesh[pi2] + height * limits[pi2] * growthvectors[pi2];
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double ab_base = (b_base - a_base).Length();
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Vec<3> a_vec = (a_end - a_base);
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Vec<3> b_vec = (b_end - b_base);
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// Calculate parallel projections
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Vec<3> ab_base_norm = (b_base - a_base).Normalize();
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double a_vec_x = Dot(a_vec, ab_base_norm);
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double b_vec_x = Dot(b_vec, -ab_base_norm);
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double ratio_parallel = (a_vec_x + b_vec_x) / ab_base;
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double PARALLEL_RATIO_LIMIT = 0.85;
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if (ratio_parallel > PARALLEL_RATIO_LIMIT) {
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// Adjust limits, vectors, and projections if parallel ratio exceeds the limit
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double corrector = PARALLEL_RATIO_LIMIT / ratio_parallel;
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limits[pi1] *= corrector;
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limits[pi2] *= corrector;
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}
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};
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auto perpendicular_limiter = [&](PointIndex pi1, PointIndex pi2, SurfaceElementIndex si) {
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// this part is same as in parallel limiter, but note that limits contents are already changed
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MeshPoint& a_base = mesh[pi1];
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MeshPoint& b_base = mesh[pi2];
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MeshPoint a_end = mesh[pi1] + height * limits[pi1] * growthvectors[pi1];
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MeshPoint b_end = mesh[pi2] + height * limits[pi2] * growthvectors[pi2];
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double ab_base = (b_base - a_base).Length();
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Vec<3> a_vec = (a_end - a_base);
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Vec<3> b_vec = (b_end - b_base);
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// Calculate parallel projections
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Vec<3> ab_base_norm = (b_base - a_base).Normalize();
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double a_vec_x = Dot(a_vec, ab_base_norm);
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double b_vec_x = Dot(b_vec, -ab_base_norm);
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double ratio_parallel = (a_vec_x + b_vec_x) / ab_base;
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// Calculate surface normal at point si
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Vec<3> surface_normal = getNormal(mesh[si]);
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double a_vec_y = abs(Dot(a_vec, surface_normal));
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double b_vec_y = abs(Dot(b_vec, surface_normal));
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double diff_perpendicular = abs(a_vec_y - b_vec_y);
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double tan_alpha = diff_perpendicular / (ab_base - a_vec_x - b_vec_x);
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double TAN_ALPHA_LIMIT = 0.36397; // Approximately 20 degrees in radians
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if (tan_alpha > TAN_ALPHA_LIMIT) {
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if (a_vec_y > b_vec_y) {
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double correction = (TAN_ALPHA_LIMIT / tan_alpha * diff_perpendicular + b_vec_y) / a_vec_y;
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limits[pi1] *= correction;
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}
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else {
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double correction = (TAN_ALPHA_LIMIT / tan_alpha * diff_perpendicular + a_vec_y) / b_vec_y;
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limits[pi2] *= correction;
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}
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}
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};
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auto neighbour_limiter = [&](PointIndex pi1, PointIndex pi2, SurfaceElementIndex si) {
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parallel_limiter(pi1, pi2, si);
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perpendicular_limiter(pi1, pi2, si);
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};
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auto modifiedsmooth = [&](size_t nsteps) {
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for (auto i : Range(nsteps))
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for (SurfaceElementIndex sei : mesh.SurfaceElements().Range())
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{
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// assuming triangle
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neighbour_limiter(mesh[sei].PNum(1), mesh[sei].PNum(2), sei);
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neighbour_limiter(mesh[sei].PNum(2), mesh[sei].PNum(3), sei);
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neighbour_limiter(mesh[sei].PNum(3), mesh[sei].PNum(1), sei);
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}
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};
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auto smooth = [&] (size_t nsteps) {
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for(auto i : Range(nsteps))
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@ -189,9 +285,11 @@ namespace netgen
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bool limit_reached = true;
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double lam_lower_limit = 1.0;
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int step = 0;
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while(limit_reached || step<2)
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while(limit_reached || step<3)
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{
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if(step>0)
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if(step>1)
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lam_lower_limit *= 0.8;
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limit_reached = false;
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@ -241,7 +339,18 @@ namespace netgen
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double lam_ = 999;
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bool is_bl_sel = params.surfid.Contains(sel.GetIndex());
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if(step==0)
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if (step == 0)
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{
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face = GetMappedFace(sei, -1);
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if (isIntersectingFace(seg, face, lam_))
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{
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if (is_bl_sel)
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lam_ *= 0.5;
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lam = min(lam, lam_);
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}
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}
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if(step==1)
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{
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if(isIntersectingFace(seg, face, lam_))
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{
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@ -251,7 +360,7 @@ namespace netgen
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}
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}
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// if the opposing surface element has a boundary layer, we need to additionally intersect with the new faces
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if(step>0 && is_bl_sel)
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if(step>1 && is_bl_sel)
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{
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for(auto facei : Range(-1, sel.GetNP()))
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{
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@ -278,7 +387,7 @@ namespace netgen
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}
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self_intersection();
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smooth(3);
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modifiedsmooth(3);
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for(auto pi : Range(growthvectors))
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growthvectors[pi] *= limits[pi];
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