Displacement ventilation

Displacement ventilation supplies relatively cool air at low level and removes warmer air at high level. In the ideal two-layer model, buoyant plumes feed a warm upper layer above a sharp density interface while the supply occupies the lower layer.

At steady state, the displacement-ventilation interface lies where the total plume volume flux equals the imposed ventilation flux. For one triangular-profile wall line plume with kinematic buoyancy flux $B_0$, entrainment coefficient $\alpha$, and ventilation flux $A$ per unit span,