Buoyancy from pressure gradients

From an oceanographic perspective, the fundamental properties of seawater are temperature, salinity and pressure i.e., depth dependent). Together, these parameters control the density of the water, which in turn determines the buoyancy of the water and pressure gradients. Small density differences integrated over oceanic scales cause considerable pressure gradients and result in currents. 

The first term is the pressure at some reference point (xref, yref, zKf) in the ambient fluid far from the body the second term is the hydrostatic pressure of this ambient fluid and the third term, Pd, is the pressure component associated with dynamics of the flow. Substituting Eq. 4.1 for P into the full equations of motion, we find that Pd simply replaces P in the x and y momentum equations. But in the z momentum equation there arises the additional term pM(z)g, representing the hydrostatic pressure gradient force. The local gravitational body force pg also appears in the z momentum equation, and the imbalance between these two forces, represented by the difference p (z)g- pg, is the driving force of natural convection. By introducing P = -(l/p)(dp/d7),> and y= lp(dpldP)r, this imbalance, called the buoyancy force, can be expressed by... 

Data from over 100 wells that penetrate the pre-Cretaceous were examined as part of a larger review of overpressures within the deeper section of the Central Graben. For this purpose, only those data measurements that could be quantified as of good quality were included. When comparing pressure data between wells spatially, the relative overpressure (difference between the hydrostatic and aquifer pressure gradients) should always be quoted. The hydrostatic gradient was taken as 0.45 psi/ft from surface as standard and, where necessary, the pressure data were also corrected to remove the elfects of hydrocarbon buoyancy. 

Concerning the masses of the ions, it can be noticed that, after the original work of Debye, some authors [67, 68] proposed to correct the masses from a buoyancy effect. In the equation of motion of an ion a term was added to allow for a pressure gradient on an ion. However a question arises about this correction. Although it would be suitable for particles of macroscopic size, like colloids, its applicability to... 

The expressions far P and p may be obtained, respectively, from (3.1.15), (3.1.16) and (3.1.17). Note that the pressure gradient generated in a centrifugal field htis been replaced by means of equation (3.1.58) as a centrifugal buoyancy term in which Vi has been replaced by particle volume mp/pp) and M by rrip to provide (1 — pt/Pp])-... 

Let the medium between the flat surfaces of two bodies (now a fluid because of practical reasons) flow with a mean velocity V (Fig. 1.13). This flow results from either an imposed pressure drop or an induced buoyancy, respectively called forced and natural convection. Lettheinlettemperatureofthefluidbe72. (Note that the fluid temperature need not be Tz- Selection of Tz for this temperature eliminates temperature gradient near plate 2 and simplifies the following development.) The convection heat transfer from plate 1 is defined as the conduction in the fluid next to plate 1 (in view of the fact... 

Step 2 Transformation of pressure (in the reservoir system) into height above free water level. The reservoir-converted capillary pressure is equivalent the buoyancy pressure in the reservoir. From the water gradient and oil gradient (or gas gradient), the height above the free water level results ... 

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