buoyancy

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buoyancy

(boi`ənsē, bo͞o`yən–), upward force exerted by a fluid on any body immersed in it. Buoyant force can be explained in terms of Archimedes' principleArchimedes' principle,
principle that states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. The principle applies to both floating and submerged bodies and to all fluids, i.e., liquids and gases.
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Buoyancy

The resultant vertical force exerted on a body by a static fluid in which it is submerged or floating. The buoyant force FB acts vertically upward, in opposition to the gravitational force that causes it. Its magnitude is equal to the weight of fluid displaced, and its line of action is through the centroid of the displaced volume, which is known as the center of buoyancy. See Aerostatics, Hydrostatics

By weighing an object when it is suspended in two different fluids of known specific weight, the volume and weight of the solid may be determined. See Archimedes' principle

Another form of buoyancy, called horizontal buoyancy, is experienced by models tested in wind or water tunnels. Horizontal buoyancy results from variations in static pressure along the test section, producing a drag in closed test sections and a thrust force in open sections. These extraneous forces must be subtracted from data as a boundary correction. Wind tunnel test sections usually diverge slightly in a downstream direction to provide some correction for horizontal buoyancy.

A body floating on a static fluid has vertical stability. A small upward displacement decreases the volume of fluid displaced, hence decreasing the buoyant force and leaving an unbalanced force tending to return the body to its original position. Similarly, a small downward displacement results in a greater buoyant force, which causes an unbalanced upward force.

A body has rotational stability when a small angular displacement sets up a restoring couple that tends to return the body to its original position. When the center of gravity of the floating body is lower than its center of buoyancy, it will always have rotational stability. Many a floating body, such as a ship, has its center of gravity above its center of buoyancy. Whether such an object is rotationally stable depends upon the shape of the body.

Buoyancy

 

of a ship, the ability of a loaded ship to float in a designated position relative to the water’s surface; one of the most important features of a ship’s seaworthiness. To ensure safe operation, every vessel must have reserve buoyancy, defined as the additional weight a ship can carry and still remain afloat. Reserve buoyancy is determined by the amount of freeboard. Standards for required freeboard are established by classification societies and depend on the design of the ship and the region and season of navigation.

buoyancy

[′bȯi·ən·sē]
(fluid mechanics)
The resultant vertical force exerted on a body by a static fluid in which it is submerged or floating.
References in periodicals archive ?
nf] gives rise to strengthening of buoyancy forces in comparison to the viscous forces.
Such a shaped dummy gives successful results for simulating heat distribution and air movement above the head, resulting in values of volume flux, momentum flux, buoyancy force density, and enthalpy flux close to those for the manikin.
It is expected that for negative inclinations, the boundary layer separates with the increase in distance from leading edge, because the buoyancy force is exerted to the top of surface and causes the flow to return.
17, we conclude that when the molecular buoyancy force dominates over the thermal buoyancy force it experiences a depreciation irrespective of the directions of the buoyancy forces.
From the previous simulations and the experimental results, it was concluded that one of the solutions in preventing the hot distortion of the sand cores is increasing their weight, which would balance the buoyancy force and bring the resultant force to the minimum (or to zero).
Subject to dynamic change of boundary temperature, the buoyancy force approximated by the Boussinesq model (the third term on the right hand side of Eq.
The variation of [phi] with N shows that when the molecular buoyancy force dominates over the thermal buoyancy force the actual concentration experiences an enhancement when the buoyancy forces act in the same direction while for the forces acting in the opposite directions it experiences a depreciation in the flow region (fig.
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Due to the jets from the discharge slots, the inertial force dominates the buoyancy force and creates a mixing flow of cold and hot water close to the top diffuser figure 6(a).
Here, Ra number is defined as the ratio of buoyancy forces and (the product of) thermal and momentum diffusivities and is equal to [g[beta][DELTA]TL.
The forgoing survey suggests that a 3D simulation model taking into account the effect of buoyancy force accompanied with and the exact boundary conditions would resolve the present inaccurate agreements between simulations and experiments.
Under non-isothermal ventilation conditions, separation of the inlet air jet from the ceiling is mainly affected by the inertial force of the air jet, which is the result of jet momentum and buoyancy force caused by heating loads.