2014/05/08 by Kiyoshi Maruyama, Maruyama, Kiyoshi
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Phase Equilibria and Thermodynamics #Quantum chaos and dynamical systems
paper · pdf · doi:10.48550/arxiv.1405.1921
openalex publication_date 2014/05/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This paper presents a theory describing the energy budget of a fluid under the Boussinesq approximation: the theory is developed in a manner consistent with the conservation law of mass. It shows that no potential energy is available under the Boussinesq approximation, and also reveals that the work done by the buoyancy force due to changes in temperature corresponds to the conversion between kinetic and internal energy. This energy conversion, however, makes only an ignorable contribution to the distribution of temperature under the approximation. The Boussinesq approximation is, in physical oceanography, extended so that the motion of seawater can be studied. This paper considers this extended approximation as well. Under the extended approximation, the work done by the buoyancy force due to changes in salinity corresponds to the conversion between kinetic and potential energy. It also turns out that the conservation law of mass does not allow the condition ∇⋅\boldsymbolu=0 on the fluid velocity \boldsymbolu to be imposed under the extended approximation; the condition to be imposed instead is presented.