Table 1.

Regularized dichotomous model of acinar airways from the transitional bronchiole (generation z’= 0) and terminal alveolar sacs (generation z’=8) (Weibel et al., 2005).

z’	N	L (mm)	D (mm)	Salv (mm2)	qa	qdi	qde	${\overline{v}}_d$
0	1	1.40	0.50	7	1.30E-03	1.00E+00	9.99E-01	9.99E-01
1	2	1.33	0.50	23	4.28E-03	4.99E-01	4.97E-01	4.98E-01
2	4	1.12	0.49	67	1.25E-02	2.49E-01	2.45E-01	2.47E-01
3	8	0.93	0.40	129	2.40E-02	1.23E-01	1.20E-01	1.21E-01
4	16	0.83	0.38	219	4.07E-02	5.99E-02	5.73E-02	5.86E-02
5	32	0.70	0.36	349	6.49E-02	2.87E-02	2.66E-02	2.77E-02
6	64	0.70	0.34	661	1.23E-01	1.33E-02	1.17E-02	1.25E-02
7	125	0.70	0.31	1204	2.24E-01	5.84E-03	3.95E-03	4.89E-03
8	256	0.70	0.29	2720	5.06E-01	1.98E-03	2.22E-16	9.88E-04

z’, generation number in acinar airways; N, number of branches; L, mean length of segments; D, mean inner diameter of segments; S_alv, total alveolar surface per generation (the sum of S_alv over all z’ is ${\sum }^{S_{alv}}=5379{\text{mm}}^2$ ); q_a(z’), normalized flow rate into all alveolar sacs per generation calculated by $S_{alv}{\overline{v}}_{alv}$ where ${\overline{v}}_{alv}=1/{\sum }^{S_{alv}}$ and $\sum _{z\prime }{S}_{alv}{\overline{v}}_{alv}=1$; q_di(z \prime ), normalized flow rate at the inlet of an airway segment calculated by $[q_{di}(\text{z}\prime -1)-q_a(\text{z}\prime -1)]/\text{N}(\text{z}\prime );q_{de}(\text{z}\prime )$, normalized flow rate at the exit of an airway segment equaling $2·q_{di}\left(\text{z}’+1\right)$; the mean normalized flow rate inside an airway segment ${\overline{q}}_d$ is $\left(q_{di}+q_{de}\right)/2$. q_a, q_di and q_de are normalized flow rates by the flow rate at the transitional bronchiole $Q_{di}\left(\text{z}’=0\right)$.