Evaporation of a sessile water droplet subjected to forced convection in humid environment

Figures & data

Figure 1. Boundary conditions of the internal droplet geometry (left) and external geometry (right), where the droplet area is circumscribed.

Figure 2. Mesh no. 3 in the close proximity of the droplet.

Table 1. Mesh study.

Mesh	Number of nodes surrounding	Number of nodes droplet	DR 10^8 (kg s^−1)
1	662,052	65,782	0.3984
2	460,470	46,001	0.3965
3	319,604	31,932	0.3946

DR, drying rate.

Figure 3. Temperature and velocity fields both within the droplet and in the surrounding domain. Please note that the computational domain is extended 0.4 m above and beside the droplet, hence part of the domain is not visible in the figure.

Figure 4. Moisture distribution around the droplet. Please note that the computational domain is extended 0.4 m above and beside the droplet, hence part of the domain is not visible in the figure.

Table 2. Validation of numerical results with different setups.

	DR · 10^8 (kg s^−1)	Difference
Crafton^[^38^]	1.47; 1.53
Conduction and NC, r = 0.49 mm	1.01	≈30–35%
Conduction, NC, and MC, r = 0.49 mm	1.46	<5%
Sobac^[^11^]	2.753
Conduction and NC, r = 1.44 mm	2.746	<1%
Conduction, NC, and MC, r = 1.44 mm	3.335	≈20%

MC, Marangoni convection; NC, natural convection.

Table 3. Factors of the DOE together with corresponding results from simulations.

Run number	Ts (K)	ΔT (K)	V∞ (m s^−1)	RH (%)	θ (°)	Internal flow	DR · 10^8 (kg s^−1)
1	323.15	2	0.1	80	45	NC	0.239
2	333.15	2	0.1	80	90	NC	0.263
3	323.15	5	0.1	80	90	MC + NC	0.292
4	333.15	5	0.1	80	45	MC + NC	0.525
5	323.15	2	0.5	80	90	MC + NC	0.251
6	333.15	2	0.5	80	45	MC + NC	0.462
7	323.15	5	0.5	80	45	NC	0.384
8	333.15	5	0.5	80	90	NC	0.395
9	323.15	2	0.1	100	45	MC + NC	0.0845
10	333.15	2	0.1	100	90	MC + NC	0.108
11	323.15	5	0.1	100	90	NC	0.143
12	333.15	5	0.1	100	45	NC	0.291
13	323.15	2	0.5	100	90	NC	0.0691
14	333.15	2	0.5	100	45	NC	0.146
15	323.15	5	0.5	100	45	MC + NC	0.236
16	333.15	5	0.5	100	90	MC + NC	0.304

DOE, design of experiments; MC, Marangoni convection; NC, natural convection.

Figure 5. Flow and temperature distribution surrounding the droplet. Left: Run no. 4 presented in Table 3 (V_in = 0.1 m s⁻¹; T_s = 333.15 K; RH = 80%; ΔT = 5 K, θ = 45°). Right: Run no. 13 presented in Table 3 (V_in = 0.5 m s⁻¹; T_s = 323.15 K; RH = 100%; ΔT = 2 K, θ = 90°).

Figure 6. Moisture distribution around the droplet. Left: Run no. 4 presented in Table 3 (V_in = 0.1 m s⁻¹; T_s = 333.15 K; RH = 80%; ΔT = 5 K, θ = 45°). Right: Run no. 13 presented in Table 3 (V_in = 0.5 m s⁻¹; T_s = 323.15 K; RH = 100%; ΔT = 2 K, θ = 90°).

Figure 7. Internal flow in setup 4; V_in = 0.1 m s⁻¹; T_s = 333.15 K; RH = 80%; ΔT = 5 K, θ_init = 45°. Conduction, NC, and MC are considered in the internal flow.

Figure 8. Internal flow in setup 13; V_in = 0.5 m s⁻¹; T_s = 323.15 K; RH = 100%; ΔT = 2 K, θ_init = 90°. Conduction and NC are considered in the internal flow.

Figure 9. Coefficient plot corresponding to the DOE setup in Table 3.

Figure 10. Coefficient plot of a second DOE setup where only significant factors in the surrounding flow are considered. In addition to the factors, also the significance of the interactions is displayed.

Figure 11. Plot of the interaction between RH and ΔT.