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TECHNICAL PAPERS: Bubbles, Particles, and Droplets

# Numerical Study of Single Bubble Dynamics During Flow Boiling

[+] Author and Article Information
Ding Li

Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science,  University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095-1597

Vijay K. Dhir1

Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science,  University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095-1597vdhir@seas.ucla.edu

1

Address all correspondence to this author.

J. Heat Transfer 129(7), 864-876 (Jan 16, 2007) (13 pages) doi:10.1115/1.2717942 History: Received May 17, 2006; Revised January 16, 2007

## Abstract

Three-dimensional numerical simulation of single bubble dynamics during nucleate flow boiling is performed in this work. The range of bulk liquid velocities investigated is from $0.076to0.23m∕s$. The surface orientations at earth normal gravity are varied from an upward facing horizontal surface to vertical through 30, 45, and $60deg$. The gravity levels on an upward facing horizontal surface are varied from $1.0ge$ to $0.0001ge$. Continuity, momentum, and energy equations are solved by finite difference method and the level set method is used to capture the liquid-vapor interface. Heat transfer within the liquid micro layer is included in this model. The numerical results have been compared with data from experiments. The results show that the bulk flow velocity, heater surface orientation, and gravity levels influence the bubble dynamics.

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## Figures

Figure 1

Computational domain used in the numerical simulation

Figure 2

(a) The definition of sliding velocity. (b) Dynamic contact angle as a function of sliding velocity.

Figure 3

(a) Grid sensitivity check. (b) Bubble liftoff time as a function of grid number.

Figure 4

The comparison of bubble shape for single bubble on horizontal surface, U=0.076m∕s, ΔTw=5.3°C

Figure 5

Quantitative comparison of bubble shapes, U=0.076m∕s, ΔTw=5.3°C

Figure 6

Velocity field at the center plane around single bubble on a horizontal surface, U=0.076m∕s, ΔTw=5.3°C

Figure 7

Temperature field at the center plane around single bubble on a horizontal surface, U=0.076m∕s, ΔTw=5.3°C

Figure 8

The comparison of bubble diameter predicted from numerical simulation with experimental data obtained by Maity (5) on a horizontal surface, U=0.076m∕s, ΔTw=5.3°C

Figure 9

The comparison of bubble diameter predicted from numerical simulation with experimental data obtained by Maity (5) on a horizontal surface, U=0.076m∕s, ΔTw=5.3°C

Figure 10

Effect of bulk velocity on lift off diameter, experimental data obtained by Maity (5)

Figure 11

Effect of bulk velocity on growth period, experimental data obtained by Maity (5)

Figure 12

The comparison of bubble shape for single bubble on vertical surface, U=0.076m∕s, ΔTw=5.3°C

Figure 13

Comparison of bubble shapes, U=0.076m∕s, ΔTw=5.3°C

Figure 14

Velocity field during bubble growth, sliding and liftoff on a vertical surface, U=0.076m∕s, ΔTw=5.3°C

Figure 15

Temperature field with temperature interval of 0.5°C on vertical surface, U=0.076m∕s, ΔTw=5.3°C

Figure 16

The comparison of bubble diameter predicted from numerical simulation with experimental data obtained by Maity (5) on a vertical surface, U=0.076m∕s, ΔTw=5.3°C

Figure 17

The dimensionless pressure contours near the bubble when the bubble is about to lift off from the vertical surface, U=0.076m∕s, ΔTw=5.3°C

Figure 18

Comparison of bubble shape predicted from numerical simulation and observed in experiment for a single bubble on 45deg inclined surface, U=0.076m∕s, ΔTw=5.3°C

Figure 19

The comparison of bubble diameter as a function of time predicted from numerical simulation with experimental data obtained by Maity (5) on 45deg inclined surface, U=0.076m∕s, ΔTw=5.3°C

Figure 20

Effect of orientation on bubble liftoff diameter, experimental data obtained by Maity (5), U=0.076m∕s, ΔTw=5.3°C

Figure 21

Bubble diameter at liftoff on an upward facing horizontal surface as a function of gravity level, ΔTw=5.3°C

Figure 22

Bubble growth period on an upward facing horizontal surface as a function of the gravity level, ΔTw=5.3°C

Figure 23

Bubble diameter at liftoff as a function of the bulk flow velocity for different gravity levels, ΔTw=5.3°C

Figure 24

Bubble growth period as a function of the bulk flow velocity for different gravity levels

Figure 25

Comparison of measured bubble diameter and numerical predictions for reduced gravity conditions, g=0.05ge, ΔTw=3.8°C, ΔTsub=1.5°C, U=0.076m∕s

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