Tall towers do not only block the wind: they deflect it down onto the street and squeeze it around their corners. Move the towers, add a canopy or trees, and see which parts of the plaza stay comfortable.
Each button recomputes the full comfort map for several values (all eight wind directions weighted by the climate).
The science
Wind profile. The approach wind follows a power law U(z) = U10 (z / 10 m)α with the exponent from the terrain roughness z0 (Counihan form α = 0.24 + 0.096 log10 z0 + 0.016 (log10 z0)²). Pedestrians feel z = 2 m, where the wind is much weaker than at 10 m or at tower-top height.
Corner acceleration. Each tower is a circular cylinder of radius R in 2-D potential flow: complex velocity w = U (1 − Σ R² / (z − zi)²). For a single cylinder the speed on the sides is exactly 2 U (at 90° from the stagnation point) and zero at the upstream stagnation point, where the pressure coefficient is Cp = 1 − (V/U)² = 1. Superposing the doublets of several towers is an approximation: it is divergence-free but each tower only roughly satisfies no-penetration in the presence of the others.
Downwash. On the upwind face the stagnation pressure rises with height (½ ρ U(z)²), so air flows down the face and spreads along the ground. Illustrative empirical model: ΔV = cdw fH fw exp(−((d − R)/(2.2 R))²) (U(0.67 H) − U(2 m)), with cdw = 0.45, fH = clamp(H/B − 0.5, 0, 1) (towers lower than about 1.5 × their width give none), fw = the upwind-side weight, d the distance from the tower axis. A podium canopy or a stepped base cuts cdw by 65 % (typical qualitative guidance, not a measurement).
Trees. Each tree sheltering factor is 1 − 0.35 ρt exp(−(d/12 m)²), multiplied over nearby trees (ρt = density slider; illustrative).
Comfort. Hourly mean wind speeds at the site follow a Weibull law P(V > v) = exp(−(v/c)k) with k = 2. At a spot the local speed is Ad × the 10 m wind for wind direction d, so P(V > v) = Σd pd exp(−(v / (Ad c))²) over eight directions (wind rose: 0.35 prevailing, ±45° 0.17 each, ±90° 0.09, ±135° 0.05, 180° 0.03). Lawson (LDDC) categories use thresholds exceeded for less than 5 % of hours: sitting 4 m/s, standing 6, strolling 8, business walking 10, otherwise uncomfortable.
Simplifications. 2-D flow at one height (no wake, no vortex shedding, no gusts beyond the Weibull spread, no building shape effects such as chamfers), towers as circles, stable neutral atmosphere, one wind rose for all hours. Constants are typical order-of-magnitude values: a real study uses a wind tunnel or CFD. Assets built with Blender; scene by Three.js.