Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

The contribution of the giraffe to hemodynamic knowledge: a unified physical principle for the circulation.

Abstract: Hemodynamics stands on three main physical principles: the hydrostatic pressure, firstly described by Stevino, the viscous flow pressure, described by Poiseuille and the total hydraulic energy, or Bernoulli's equation. However, neither of these physical principles gives a comprehensive description of the single pressure measurement in the cardiovascular system. Hence, all these principles should be used together to fully describe the physical forces acting in the circulation of blood. Experiments that measured the hydrostatic pressure in the jugular vein of the giraffe have shown that a few guidelines need to be followed to measure it correctly. Following these guidelines, it can be seen that hydrostatic and viscous flow pressures are strictly related to one another, and that this relationship is described in mathematical terms. In addition, it has been shown that hydrostatic and viscous pressures should be included in Bernoulli's principle, to give the combined Bernoulli-Poiseuille equation. This unified principle is helpful not only to measure correctly the pressure with a catheter connected to a pressure transducer, but also to give to the pressure measured in a patient with the mercury manometer, a strong connection with the description of the pressure as a physical force acting inside the circulation. In addition it provides a comprehensive view of the cardiovascular system as a closed hydrodynamic system, in which the heart is a pump, that does not normally work to overcome the force of gravity. The question at this point is: are there any pathophysiological conditions in which the heart needs to be confronted with the sudden appearance of the force of gravity inside the cardiovascular system?

Stability of hydrostatic equilibrium for the 2D BMHD system with partial dissipation

Abstract:

In this paper, we establish the nonlinear stability and large time behavior of hydrostatic equilibrium in a uniform magnetic field for the Boussinesq system with magnetohydrodynamics convection in the whole space \begin{document}$ \mathbb{R}^{2} $\end{document} with mixed partial dissipation, motivated by Lai, Wu, Zhong [18] and Lin, Ji, Wu and Yan [22]. Due to the lack of horizontal dissipation and vertical dissipation in the second component of velocity, the natural energy is not easy to be closed, which is overcome by introducing an additional functional of the horizontal derivative of the second component of velocity. This shows that the magnetic field and the temperature have a stabilizing effect on the fluid. Large time behavior and linear decay rate of the solution are also obtained.

Circulation of matter and evolution of the internal magnetic field in neutron stars

Abstract: Neutron stars may be in hydrostatic equilibrium only for very particular magnetic configurations with conservative magnetohydrodynamic forces. We consider the magnetohydrodynamic evolution of a neutron star with a non-zero external dipole field component. The ohmic dissipation should slightly change tits equilibrium distribution of the currents, producing a slow circulation of matter which tends to maintain the magnetic configuration close to an equilibrium one. The evolution of a strong magnetic field (B≃10 12 -10 13 G) under the influence of both ohmic dissipation and circulation is analysed in detail. The resulting field decay turns out to be crucially dependent on the thermal history of the neutron star