What question did this study set out to answer?

This research aims to explore how bubble velocity is affected by thermal conditions and water height in fluid dynamics.

April 8, 2026Thermo1 citationsOpen Access

Analyzing the Influence of Bubble Velocity on Fluid Dynamics Considering Thermal and Water Height Effects via PIV

HAHassan AbdulmoutiHigher Colleges of Technology MEMuhammed ElmnefiOstim Technical University MHMuhanad HajjawiHigher Colleges of Technology

Key Points

This research aims to explore how bubble velocity is affected by thermal conditions and water height in fluid dynamics.
Experimental investigation using a two-dimensional Particle Image Velocimetry system.
Setup included a transparent acrylic tank with a bubble generator and heating system.
Experiments varied water temperature, air flow rates, and water depths.
Bubble rising velocity increases with water temperature, gas flow rate, and water depth.
Increasing temperature from 40 °C to 60 °C doubled bubble rising velocity due to reduced viscosity.
Surrounding fluid velocity reaches 30–60% of bubble rising velocity, revealing strong coupling effects.

Abstract

This study experimentally investigates the dynamics of air bubble plumes in water under varying thermal and hydrodynamic conditions using a two-dimensional Particle Image Velocimetry (PIV) system. The experimental setup consists of a transparent acrylic tank equipped with a bubble generator, a controlled heating system, and a synchronized PIV arrangement to capture both bubble motion and the induced liquid flow field. Experiments were conducted over a range of water temperatures (21–60 °C), air flow rates, and water depths (200–600 mm) to systematically quantify their coupled influence on bubble plume behavior. The results demonstrate that bubble rising velocity (defined here as the mean vertical, buoyancy-driven component of bubble motion measured in the fully developed plume region) increases with water temperature, gas flow rate, and water depth. For a fixed gas flow rate and water depth, increasing the water temperature from 40 °C to 60 °C resulted in an approximately twofold increase in bubble rising velocity, primarily due to reduced liquid viscosity and enhanced buoyancy forces. Bubble velocity also increased with gas flow rate and water depth, reflecting stronger momentum input and extended acceleration distances within taller water columns. PIV-resolved velocity fields further reveal that the surrounding fluid velocity increases proportionally with bubble rising velocity and temperature, confirming a strong coupling between bubble motion and plume-induced circulation. The surrounding liquid velocity reached approximately 30–60% of the corresponding bubble rising velocity, depending on operating conditions. These findings provide quantitative experimental insight into the coupled effects of thermal conditions, gas injection rate, and liquid depth on bubble–liquid interactions. The results contribute valuable validation data for multiphase flow modeling and offer practical relevance for thermal–hydraulic, chemical, and environmental engineering applications involving bubble-driven transport processes.

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