Pressure variation with height

Let us now consider the sum of the forces upwards. F is designated as the force, downwards, needed to hold the balloon in place. Another force is due to the pressure distribution of the cold atmosphere on the balloon. Assuming the atmosphere is motionless, fluid statistics gives the pressure variation with height x as... 

For describing the gas-velocity profile in the spout, Lefroy and Davidson started with the assumption, already discussed in Section IV,C, that the pressure variation with height in a spouted bed follows a quarter-cosine curve ... 

Figure 10.2 Variation with height of the properties of a mixture in the diffusion cloud chamber. Shown are the rnas.s densities of the carrier gas. ph, and the vapor,, the equilibrium vapor pressure, p, the partial pre.ssure of (he vapor, p, the temperature, 7/, and the saturation ratio, S. The highest temperature, vapor pressure, and gas density are at the chamber bottom, above the heated pool. The distributions with respect to chamber height are calculated by integrating expressions for the steady-state fluxes of heat and mass through the chamber...

Look up atmospheric pressure variation with altitude. At what height would human blood... 

Airflows are determined basically by a steady-state calculation for each time step. At each time step, first, pressures at external nodes are calculated on the basis of the wind pressure coefficients and the actual wind speed and direction. Then, for all conductances, the local pressures at each side of the link are calculated. At internal links, this pressure is dependent on the (unknown) zone pressure p and the aerostatic pressure variation due to the height of the link with respect to the zone reference height. At external links, this pressure is dependent on the external node pressure and the aerostatic pressure variation due to the height of the link with respect to the stack reference height. For the aerostatic pressure, the air density is determined considering the temperature, the humidity, and (if relevant) the contaminant concentrations in the zone or in the outside air, respectively. From this, the pressure differences across each conductance can be calculated, and from this the mass airflow tor each conductance /. 

In the Flixborough disaster, one of six reactors in series, through which hot cyclohexane was passed, was removed from service (see Figure 2.1). Each reactor was connected by a short pipe with a bellows at each end to allow for expansion. The fifth reactor was replaced by a temporary bypass pipe with two bends in it to allow for differences in height between reactors 4 and 6. Because the bypass was not properly supported and had a bellows at either end, it moved when there were pressure variations. This movement eventually caused the bellows to fail, releasing 50 tons of cyclohexane which exploded, killing 28 men. 

The variation of pressure with height derived in Equation 7.9 can be substituted to give the variation of temperature with height ... 

Flabitable and continually habitable zone Variation of temperature and pressure with height Steady-state atmospheric networks leading to Chapman layers... 

From equation 2.43 in Volume 1, the variation of pressure with height is given by ... 

H.M. Princen and A.D. Kiss Osmotic Pressure of Foams and Highly Concentrated Emulsions. 2. Determination from the Variation in Volume Fraction with Height in an Equilibrated Column. Langmuir 3, 36 (1987). 

Concentrations of contaminants in the atmosphere may vary significantly from time to time due to seasonal climatic variation, atmospheric turbulence, and velocity and direction of wind. The most important meteorological factors are (1) wind conditions and the gustiness of wind, (2) the humidity and precipitation, (3) the temperature, which varies with latitude and altitude, (4) barometric pressure (varying with the height above the ground), and (5) solar radiation and the hours of sunshine, which vary with the season. 

Illustration 3.—The variation of atmospheric pressure with altitude above sea-level can be shown to follow the compound interest law. Let pQ be the pressure in centimetres of mercury at the so-called datum line, or sea-level, p the pressure at a height h above this level. Let p0 be the density of air at sea-level (Hg = 1). Now the pressure at the sea-level is produced by the weight of... 

The Earth s atmosphere is characterized by variations of temperature and pressure with height. In fact, the variation of the average temperature profile with altitude is the basis for distinguishing the layers of the atmosphere. The regions of the atmosphere are (Figure 1.1) ... 

We desire the expressions for the variation of ug and vg with height it turns out to be easier to use pressure as the vertical coordinate rather than height. So we seek expressions for —dug/dp and —dvg/dp, where the minus sign allows the derivative with respect to the vertical coordinate to be taken upward (since pressure decreases with altitude). The quantities... 

Choose the system of coordinates such that the jc-axis is vertical and the y-axis is perpendicular to the plate (and directed toward the solution). The bottom edge of the plate corresponds to x = 0. Assume that the change of concentration mostly occurs in the diffusion boundary layer. Since the flow of liquid is driven by the gradient of concentration, the flow occurs in this layer, too that is, the viscous boundary layer coincides with the diffusion layer. The gravity force /)g acts on a unit solution volume. Since p changes with height, so does the force. At p = p(Co) = const, this force does not cause the flow since the force is counterbalanced by the pressure gradient. The flow may be caused by density variations from / (Co). Since the difference Ap = y9(Co) —/ (C) is small, the equations of motion in the first approximation can be written in the form... 

This equation, when integrated, approximates the pressure poorly because it ignores the change in temperature with height Figure4.5 illustrates the variation of atmospheric temperature with elevation. The temperature decreases linearly with elevation in the troposphere and mesosphere but it increases with elevation in the stratosphere and thermosphere ... 

The device was tested by characterizing the blood pressure variations at the skin surface. A droplet was filled with 3 mL electrolyte in the chamber with size of 6 mm in radius and 140 mm in height. The sensor was attached to the skin surface above the carotid artery (Fig. 6a) to record the blood pressure wave. As shown in Fig. 6b, the 15 s blood pressure variations were measured with the maximal value less than 100 Pa at around 1 Hz. In summary, simplicity and flexibility of the droplet-based capacitance... 

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