Mathematical modeling and numerical simulation of surfactant delivery within a physical model of the neonatal trachea for different aerosol characteristics

Figures & data

Figure 1. Computational geometry and boundary conditions for (a) Domain 1 and (b) Domain 2.

Table 1. Uniform droplet aerodynamic diameter (D_a) and mass flow rate (m) for each partial injection, for PFD and surfactant aerosols.

	PFD		Surfactant
Injection N°	Da (µm)	m (mg/s)	Da (µm)	m (mg/s)
1	0.524	0.009	0.730	0.004
2	0.785	0.006	1.09	0.009
3	1.17	0.10	1.63	0.05
4	1.76	0.62	2.46	0.24
5	2.64	2.18	3.67	0.71
6	3.94	2.89	5.50	1.42
7	5.91	1.56	8.24	1.01
8	8.84	0.48	12.33	0.56
9	13.24	0.35	18.43	0.40
10	19.82	0.12	27.66	0.06

Data obtained from experimental measurements.

Figure 2. Comparison of experimental and numerical air axial velocity profiles (a) 30 mm beyond the distal tip of the IC and (b) 5 mm beyond the exit of the G0 of the physical model, for a driving pressure of 4 bar.

Table 2. Experimental and numerical results of droplet size characterization 35 mm (surfactant) and 60 mm (PFD) beyond the distal tip of the IC and 10 mm beyond the G0 of the physical model.

	PFD				Surfactant
	Beyond IC		Beyond G0		Beyond IC		Beyond G0
	Exp.	CFD	Exp.	CFD	Exp.	CFD	Exp.	CFD
Mean Da (µm)	1.1	2.5	4.5	2.9	0.9	1.8	0.9	2.9
MMAD (µm)	4.4	3.4	4.9	6.0	6.7	6.1	10.7	10.5

Beyond IC: Domain 1. Beyond G0: Domain 2.

Figure 3. Comparison of experimental and numerical cumulative mass based droplet size distribution curves (a) 35 mm (surfactant) and 60 mm (PFD) beyond the distal tip of the IC, and (b) 10 mm beyond the exit of the G0 of the physical model. Beyond IC: Domain 1. Beyond G0: Domain 2.

Table 3. Numerical results of the percentage distribution of the atomized mass.

Mass (%)	PFD	Surfactant
Deposited at the physical model	63.4	39.1
Directed beyond the G0	10.4	23.5
In suspension	26.2	37.4

Figure 4. Numerical results of mass based droplet size distribution curves at the distal end of the G0 of the physical model. (a) Influence of injected mass flow rate. (b) Influence of injected droplet size.

Table 4. Numerical results of droplet size characterization just at the distal end of the G0 of the physical model for different surfactant aerosols.

	Droplet mass flow rate			Droplet size
	4.47 mg/s^*	2.23 mg/s	8.93 mg/s	Original^*	2 μm monodisperse
Mean Da (µm)	2.7	2.5	3.8	2.7	3.0
MMAD (µm)	9.8	8.7	9.4	9.8	7.1

* Original surfactant aerosol generated by the IC.

Table 5. Numerical results of the percentage distribution of the atomized mass for different surfactant aerosols.

	Droplet mass flow rate			Droplet size
Mass (%)	4.47 mg/s^*	2.23 mg/s	8.93 mg/s	Original^*	2 μm monodisperse
Deposited at the physical model	39.1	25.0	46.7	39.1	45.3
Directed beyond the G0	23.5	19.0	24.3	23.5	10.3
In suspension	37.4	56.0	29.0	37.4	44.4

* Original surfactant aerosol generated by the IC.

Figure 5. Numerical results of the behavior of surfactant aerosols within the physical model and the aerosol cone angle (α) beyond the G0 for different mass flow rates and droplet sizes.