Numerical investigation of temperature increment effect on bubble dynamics in stagnant water and Al₂O₃ nanofluid column

ABSTRACT

Formation, growth, and detachment of injected air bubble from a submerged needle in stagnant liquid at the different temperature of fluid, investigated numerically. Experiments have been done for validation of numerical simulation results. The injection flow rate of air was varied between 600 and 1200 mL/h in experimental study. Bubble formation, growth, and detachment information were obtained using high speed camera and visual photography technique. Young–Laplace equation that was derived from the force balance on the bubble, was utilized in numerical simulation. A novel method was used for solution of Young–Laplace equation. The bubble diameter, instantaneous contact angle, volume, and other characteristics of bubble were studied at different temperature of operating condition. Also, the enhancement of temperature in Al₂O₃ nanofluid with 0.01% volume concentration (φ = 0.01%) was compared with deionized water results. The results reveal that by increasing the Al₂O₃ nanofluid and the deionized water temperature, the diameter, volume, and center of gravity of bubble decrease; however, the instantaneous contact angle increases. Meanwhile, the size of bubble at Al₂O₃ nanofluid is larger than of that in deionized water at same temperature. Also, the bubble aspect ratio is almost senseless to temperature increment in both deionized water and Al₂O₃ nanofluid. Eventually, the variation of operating temperature and adding of nanoparticle to the deionized water have significant influence on behavior of growing bubble.

KEYWORDS:

• Al₂O₃ nanofluid
• bubble dynamics
• gas injection
• numerical simulation
• temperature increment
• Young–Laplace equation

Highlight

• Temperature increment’s effect on gas bubble characteristics was studied numerically

• The Young–Laplace equation was used for simulation of bubble profile in Al₂O₃ nanofluid and deionized water

• Experimental studies were performed for validation of numerical simulation

• The bubble volume, diameter, and center of gravity decrease with increment of temperature

• The bubble’s degree of sphericity decreases with increase of Bond number

Additional information

Funding

The financial support for this work was provided by the Iranian National Science Foundation (INSF) under Grant Number of 93036137.