Human convective boundary layer and its interaction with room ventilation flow.

Area of Science:

• Fluid dynamics
• Human-environment interaction
• Thermal comfort

Background:

• Understanding airflow around the human body is crucial for thermal comfort and safety.
• The human convective boundary layer (CBL) plays a key role in heat and mass transfer.
• External airflow interactions with the CBL are not fully understood.

Purpose of the Study:

• To investigate the impact of uniform airflow velocity and direction on the human CBL.
• To quantify airflow alterations in the breathing zone under various airflow conditions.
• To analyze the influence of airflow on heat and mass transfer around a human body model.

Main Methods:

• Utilized a thermal manikin with realistic body shape and temperature distribution.
• Employed Particle Image Velocimetry (PIV) and Pseudocolor Visualization (PCV) for flow analysis.
• Simulated various uniform airflow conditions (velocity, direction) around the manikin.

Main Results:

• External airflow direction and magnitude significantly influence airflow distribution around the body.
• Downward airflow at 0.30 m/s reduced peak velocity in the breathing zone by colliding with the CBL.
• Transverse horizontal airflow disturbed the CBL at the breathing zone even at 0.175 m/s.
• Assisting airflow from below reduced peak velocity and altered flow patterns, influenced by the chair.

Conclusions:

• External airflow dynamics critically affect the human CBL and airflow in the breathing zone.
• Airflow velocity and direction must be considered for accurate thermal comfort and exposure assessments.
• The presence of furniture, like chairs, can further modify airflow interactions with the human body.