Eckert Number
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The Eckert number (Ec) is a dimensionless parameter used in fluid mechanics to characterize the ratio of kinetic energy to enthalpy in a fluid flow. It’s named after the German physicist Ernst R. G. Eckert.
Eckert number is used in momentum and heat transfer in general and compressible flow calculations in particular. It is normally defined in the following form above.
Where: | ||
Cp | = | Heat capacity |
delta-T | = | Temperature difference |
V_inf | = | Velocity of fluid far from body |
The Eckert number provides insights into the balance between kinetic energy and thermal energy in a fluid flow. It’s particularly relevant in the analysis of heat transfer processes, such as in convective heat transfer and boundary layer flows.
Depending on the value of the Eckert number, different flow regimes can be identified:
- If Ec ≪ 1, the kinetic energy of the flow is small compared to the enthalpy difference, indicating that thermal energy dominates over kinetic energy. This typically occurs in situations where heat transfer is significant relative to fluid motion.
- If Ec ≫ 1, the kinetic energy of the flow is large compared to the enthalpy difference, indicating that kinetic energy dominates over thermal energy. This typically occurs in situations where fluid motion is significant relative to heat transfer.
The Eckert number is commonly used in the analysis and design of various engineering systems involving fluid flow and heat transfer, such as in the design of turbomachinery, cooling systems, and thermal management devices.
