Laminar cylinder
In one minuteA viscous case with separation — the steady wake of a circular cylinder at Reynolds number 40 — showing no-slip walls, skin friction and the separation point.
Fields: velocity_x [-0.0964, 1.161], mach [8.03e-05, 0.2359], pressure [17.38, 18.49], temperature [0.9974, 1.009]. Raw sample (JSON)
gyre 0.4.0 · 39979fcf90 · · cpu · example_cylinder/field.jsonSame code as this build
Steady separated flow past a circular cylinder at Re_D = 40, Mach 0.2 (p = 3, 24 x 10 curved elements). Surface pressure and skin friction over the upper half, from the front stagnation point (0°) to the rear (180°).
- convergedyesexpected truepass
- drag coefficient1.537expected 1.45 … 1.65pass
- front stagnation cp1.153expected 1.0 … 1.25pass
- separation angle from the rear stagnation point [deg]53.75expected 45 … 60pass
gyre 0.4.0 · 39979fcf90 · · cpu · quick suite · record (JSON)Same code as this build
gyre run cylinder_re40 -o runs/cylinder
The preset uses a 24 × 10 curved O-mesh reaching 40 diameters, , an adiabatic no-slip wall and a far-field boundary at Mach 0.2.
| cd | cl | separation from rear [deg] | Newton steps | DOF | field |
|---|---|---|---|---|---|
| 1.53727 | -1.7153e-14 | 53.7473 | 16 | 15360 | example_cylinder/field.json |
gyre 0.4.0 · 39979fcf90 · · cpu · quick suite · record (JSON)Same code as this build
Data table
| θ from front stagnation [deg] | cp |
|---|---|
| 4.1459 | 1.15293 |
| 10.8541 | 1.07967 |
| 15 | 1.00662 |
| 15 | 1.00292 |
| 19.1459 | 0.905836 |
| 25.8541 | 0.710071 |
| 30 | 0.573596 |
| 30 | 0.567372 |
| 34.1459 | 0.419849 |
| 40.8541 | 0.165764 |
| 45 | 0.00371642 |
| 45 | 0.0107632 |
| 49.1459 | -0.145918 |
| 55.8541 | -0.377553 |
| 60 | -0.502503 |
| 60 | -0.508746 |
| 64.1459 | -0.615786 |
| 70.8541 | -0.761584 |
| 75 | -0.825954 |
| 75 | -0.829818 |
| 79.1459 | -0.874213 |
| 85.8541 | -0.916813 |
| 90 | -0.922989 |
| 90 | -0.922387 |
| 94.1459 | -0.91662 |
| 100.854 | -0.887142 |
| 105 | -0.861206 |
| 105 | -0.859542 |
| 109.146 | -0.830883 |
| 115.854 | -0.777551 |
| 120 | -0.747173 |
| 120 | -0.744984 |
| 124.146 | -0.715562 |
| 130.854 | -0.668527 |
| 135 | -0.644654 |
| 135 | -0.643014 |
| 139.146 | -0.620141 |
| 145.854 | -0.586121 |
| 150 | -0.567973 |
| 150 | -0.56663 |
| 154.146 | -0.550636 |
| 160.854 | -0.526003 |
| 165 | -0.514384 |
| 165 | -0.513175 |
| 169.146 | -0.504217 |
| 175.854 | -0.494036 |
| 180 | -0.492681 |
| 180 | -0.492681 |
gyre 0.4.0 · 39979fcf90 · · cpu · quick suite · record (JSON)Same code as this build
The sign change marks separation; literature places it about 53° from the rear stagnation point at Re = 40.
Data table
| θ from front stagnation [deg] | cf |
|---|---|
| 4.1459 | 0.0734808 |
| 10.8541 | 0.185903 |
| 15 | 0.258294 |
| 15 | 0.250527 |
| 19.1459 | 0.318278 |
| 25.8541 | 0.40863 |
| 30 | 0.460132 |
| 30 | 0.456147 |
| 34.1459 | 0.49935 |
| 40.8541 | 0.548881 |
| 45 | 0.568988 |
| 45 | 0.568032 |
| 49.1459 | 0.578289 |
| 55.8541 | 0.576352 |
| 60 | 0.559642 |
| 60 | 0.564671 |
| 64.1459 | 0.539849 |
| 70.8541 | 0.49041 |
| 75 | 0.44672 |
| 75 | 0.452809 |
| 79.1459 | 0.406092 |
| 85.8541 | 0.331474 |
| 90 | 0.284805 |
| 90 | 0.280959 |
| 94.1459 | 0.236672 |
| 100.854 | 0.167521 |
| 105 | 0.128622 |
| 105 | 0.129719 |
| 109.146 | 0.0947858 |
| 115.854 | 0.0488208 |
| 120 | 0.0265861 |
| 120 | 0.0265019 |
| 124.146 | 0.00717135 |
| 130.854 | -0.0156629 |
| 135 | -0.0251225 |
| 135 | -0.0255124 |
| 139.146 | -0.033027 |
| 145.854 | -0.0402093 |
| 150 | -0.0415744 |
| 150 | -0.0418127 |
| 154.146 | -0.041486 |
| 160.854 | -0.0368469 |
| 165 | -0.0307411 |
| 165 | -0.0314626 |
| 169.146 | -0.0240381 |
| 175.854 | -0.00990457 |
| 180 | -5.8400e-04 |
| 180 | 5.8400e-04 |
gyre 0.4.0 · 39979fcf90 · · cpu · quick suite · record (JSON)Same code as this build
- Pressure recovers only partly on the rear half: the flow has separated.
- The skin friction changes sign where the flow separates. Its location is reported in the table as the angle from the rear stagnation point.
- The drag coefficient is compared with the literature in Physical validation.
The wall imposes zero velocity through the BR2 lifting and zero heat flux through the viscous
boundary flux (boundary conditions). The numerical energy
flux through the adiabatic wall is zero by construction, for any state. The
validation study checks instead that the conduction the
converged solution carries at the wall, which vanishes for the exact solution, decreases with
the polynomial degree. The Reynolds number is a differentiable input: --gradients --of cd --wrt re,mach.