Characteristics of air and water velocity fields during natural convection |
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Authors: | Syed J K Bukhari M H Kamran Siddiqui |
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Institution: | (1) Department of Mechanical and Industrial Engineering, Concordia University, Montreal, QUE, Canada, H3G 1M8 |
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Abstract: | Air and water velocity fields have been simulated during natural convection, using a two-dimensional volume of fluid (VOF)
model. The results have shown that during unstable thermal stratification, the root-mean-square (RMS) airside velocities are
an order of magnitude higher than the RMS waterside velocities, whereas, during the stable thermal stratification, the velocity
magnitudes are comparable for air and water sides. Furthermore, the magnitude of the air velocity changed more rapidly with
the change in the bulk air–water temperature difference than the water velocity, indicating that the air velocities are more
sensitive to the bulk air and water temperature difference than the water velocities. A physical model of the heat and mass
transfer across the air–water interface is defined. According to this model, the vortices on the air and water sides play
an important role in enhancing the heat and mass transfer. Due to the significance of the flow velocities in the transport
process, it has been proposed that the correlations for the heat and mass transfer during natural convection should be improved
by incorporating the flow velocity as a parameter. |
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Keywords: | |
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