Buoyancy effect

If a 1-kg stainless weight (m = 1, OOOg, = 8,000 kg/m ) is added to one pan of the balance in Figure 1, and material with a density of 1,000 kg/m is added to the other until equiHbrium is reached, the amount of the material needed is 1001.05 g, using equation 5. Thus, it takes 1001.05 g of this material to counterbalance 1,000 g of stainless steel, because of the buoyancy effects on the dissimilar volumes. 

The physics and modeling of turbulent flows are affected by combustion through the production of density variations, buoyancy effects, dilation due to heat release, molecular transport, and instabiUty (1,2,3,5,8). Consequently, the conservation equations need to be modified to take these effects into account. This modification is achieved by the use of statistical quantities in the conservation equations. For example, because of the variations and fluctuations in the density that occur in turbulent combustion flows, density weighted mean values, or Favre mean values, are used for velocity components, mass fractions, enthalpy, and temperature. The turbulent diffusion flame can also be treated in terms of a probabiUty distribution function (pdf), the shape of which is assumed to be known a priori (1). 

Turner,. S. 1973. Buoyancy Effects in Fluids. Cambridge University Press, Cambridge. 

Use of warm processes on a downdraft table should be avoided since the air velocity created by the exhaust is often lower than the velocity due to buoyancy effects. Effective use of a downdraft table for welding requires velocities high enough to counteract the buoyancy, which could result in disturbances of the welding process. 

The flow field created within the protection zone depends mainly on the density difference between supply air and room air (Fig. 10.90). With vertical flow the supply air should be isothermal or cooler than ambient air. If it were warmer, the extension of the controlled flow would be reduced due to buoyancy effects, resulting in the supply air not reaching the operator s breathing zone. As the. supply air cannot be used for heating, the operator s thermal comfort should be maintained, preferably with radiant heaters in cold environments. If the supply air temperature is lower than the room air, the denser supply air accelerates down to the operator, and for continuity reasons the supply flow contracts. Excessive temperature differences result in a reduced controlled flow area with thermal discomfort, and should only be used in special cases. 

Tension Casing suspended at the surface. Weight reduction due to buoyancy effect is ignored. Safety factor = 1.6. 

For conditions in which only natural convection occurs, the velocity is dependent on the buoyancy effects alone, represented by the Grashof number, and the Reynolds group may be omitted. Again, when forced convection occurs the effects of natural convection are usually negligible and the Grashof number may be omitted. Thus ... 

For these processes which depend on buoyancy effects, the rate of heat transfer might be expected to follow a relation of the form ... 

T. Echekki, J. -Y. Ghen, and U. Hedge, Numerical investigation of buoyancy effects on triple flame stability. Combust. Sci. Technol. 176(3) 381-407, 2004. 

There are several boiling regimes in pool boiling as well as in flow boiling. The only difference lies in the influence of flow effect. The buoyancy effect is significant... 

The buoyancy effect—Being lighter than liquid, the bubble slips through the adjacent liquid that flows downstream. 

In a vertical upward gas-liquid flow, a continuous swarm of bubbles flows upward with the liquid stream due to a buoyancy effect, and the gas slips past the liquid with a relative velocity U0 (rise velocity) ... 

Altenkirch, R.A., Eichhorn, R. and Shang, P.C., Buoyancy effects on flames spreading down thermally thin fuels, Combustion and Flame, 1980, 37, 71-83. 

Air buoyancy, effect on weighing, 26 242 Air classification, of wheat flour, 26 282 Air cleaners, to improve indoor air quality, 1 820, 831-834... 

All measured values are normally registered by means of a recorder. In addition, an improved method for data collection and processing is possible today by use of a computer. This has the advantage of automatic, safer data collection in an easy-to-read form. Comparison with standard values, correction of the buoyancy effects, control of linearity, control of standard deviations and peak integrations are thus possible. 

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